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  Subjects -> ENGINEERING (Total: 2282 journals)
    - CHEMICAL ENGINEERING (192 journals)
    - CIVIL ENGINEERING (186 journals)
    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1204 journals)
    - ENGINEERING MECHANICS AND MATERIALS (385 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (68 journals)
    - MECHANICAL ENGINEERING (90 journals)

CIVIL ENGINEERING (186 journals)                     

Showing 1 - 186 of 186 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 17)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 34)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 27)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 30)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 1)
Archives of Civil Engineering     Open Access   (Followers: 10)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 1)
ATBU Journal of Environmental Technology     Open Access   (Followers: 3)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 9)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 4)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Berkeley Planning Journal     Open Access   (Followers: 7)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 15)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 15)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 11)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 10)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 17)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 2)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 5)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 7)
Civil And Environmental Engineering Reports     Open Access   (Followers: 5)
Civil and Environmental Research     Open Access   (Followers: 19)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 17)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 9)
Civil Engineering Dimension     Open Access   (Followers: 8)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 258)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 10)
Computers & Structures     Hybrid Journal   (Followers: 36)
Concrete Research Letters     Open Access   (Followers: 6)
Construction Economics and Building     Open Access   (Followers: 2)
Construction Engineering     Open Access   (Followers: 8)
Construction Management and Economics     Hybrid Journal   (Followers: 21)
Construction Science     Open Access   (Followers: 4)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 2)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 16)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 14)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 8)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 16)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 4)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 6)
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 22)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 16)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 13)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 8)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 4)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 10)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 4)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 6)
International Journal Sustainable Construction & Design     Open Access  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 11)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 7)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Society     Hybrid Journal   (Followers: 3)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 24)
Journal of Construction Engineering     Open Access   (Followers: 7)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 19)
Journal of Construction Engineering, Technology & Management     Full-text available via subscription   (Followers: 4)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 8)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 11)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 12)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 21)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 4)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Offshore Structure and Technology     Full-text available via subscription  
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 4)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 7)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 39)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 4)
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access  
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access  
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 17)
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 6)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 2)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 4)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 7)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 11)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 4)
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Recent Trends In Civil Engineering & Technology     Full-text available via subscription   (Followers: 4)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 7)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 9)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 6)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 4)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 9)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 11)
Structural Safety     Hybrid Journal   (Followers: 7)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 23)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 12)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 8)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access  
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 6)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)

           

Journal Cover Earthquake Engineering and Structural Dynamics
  [SJR: 2.921]   [H-I: 83]   [16 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0098-8847 - ISSN (Online) 1096-9845
   Published by John Wiley and Sons Homepage  [1577 journals]
  • Direct design method based on seismic capacity redundancy for structures
           with metal yielding dampers
    • Authors: Linfei Hao; Ruifu Zhang, Kiwoong Jin
      Abstract: In this study, a direct static design method for structures with metal yielding dampers is proposed based on a new design target called the seismic capacity redundancy indicator (SCRI). The proposed method is applicable to the design of elastic-plastic damped structures by considering the influence of damper on different structural performance indicators separately without the need for iteration or nonlinear dynamic analysis. The SCRI—a quantitative measure of the seismic capacity redundancy—is defined as the ratio of the seismic demand required by the target performance limit to the design seismic demand. Changes in the structural SCRI are correlated with the parameters of the supplemental dampers so that the dampers can be directly designed according to a given target SCRI. The proposed method is illustrated through application to a 12-story reinforced-concrete frame, and increment dynamic analysis is performed to verify the effectiveness of the proposed method. The seismic intensity corresponding to the target structural performance limit is regarded as a measure of the structural seismic capacity. The required seismic intensity increases after the structure is equipped with the designed metal yielding dampers according to the expected SCRI. It is concluded that the proposed method is easy to implement and feasible for performance-based design of metal yielding dampers.
      PubDate: 2017-09-19T00:05:43.899929-05:
      DOI: 10.1002/eqe.2977
       
  • Evaluation of out-of-plane seismic performance of column-to-column precast
           concrete cladding panels in one-storey industrial buildings
    • Authors: Andrea Belleri; Fabrizio Cornali, Chiara Passoni, Alessandra Marini, Paolo Riva
      Abstract: Recent earthquakes in Italy (L'Aquila 2009 and Emilia 2012) highlighted the vulnerability of precast cladding panels, typically associated with a connection system not designed to account for displacement and rotation compatibility between the panels and the supporting structure. Experimental investigations were performed in the past to investigate the in-plane performance of cladding panels and design recommendations have been made accordingly; however, in the case of out-of-plane seismic loads, the load demand is commonly evaluated in the design practice by means of formulations for nonstructural components.This paper summarizes the results obtained from parametric analyses conducted to estimate the out-of-plane load demand in column-to-column cladding panels typical of one-storey commercial and industrial buildings. Empirical equations suitable for both new and existing panels are proposed and compared with the design equations given in Eurocode 8 and ASCE 7. The paper also considers the effects of the development of plastic hinges at the column base and of the roof flexibility on the load demand in panel-to-column connections. The roof flexibility may generate the torsion of the panels; consequently, an analytical procedure to account for such effects is proposed. Finally, general design recommendations are made.
      PubDate: 2017-09-14T02:52:29.538881-05:
      DOI: 10.1002/eqe.2956
       
  • RC structures cyclic behavior simulation with a model integrating
           plasticity, damage, and bond-slip
    • Authors: Bashar Alfarah; Juan Murcia-Delso, Francisco López-Almansa, Sergio Oller
      Abstract: The behavior of reinforced concrete structures under severe demands, as strong ground motions, is highly complex; this is mainly due to the complexity of concrete behavior and to the strong interaction between concrete and steel, with several coupled failure modes. On the other hand, given the increasing awareness and concern on the worldwide seismic risk, new developments have arisen in earthquake engineering; nonetheless, some developments are mainly based on simple analytical tools that are widely used, given their moderate computational cost. This research aims to provide a solid basis for validation and calibration of such developments by using computationally efficient continuum mechanics-based tools. Within this context, this paper presents a model for 3D simulation of cyclic behavior of RC structures. The model integrates a bond-slip model developed by one of the authors and the damage variable evolution methodology for concrete damage plastic model developed by some authors. In the integrated model, a new technique is derived for efficient 3D analysis of bond-slip of 2 or more crossing reinforcing bars in beam-column joints, slabs, footings, pile caps, and other similar members. The analysis is performed by implementing the bond-slip model in a user element subroutine of Abaqus and the damage variable evolution methodology in the original concrete damage plastic model in the package. Two laboratory experiments consisting of a column and a frame subjected to cyclic displacements up to failure are simulated with the proposed formulation.
      PubDate: 2017-09-14T02:52:15.817865-05:
      DOI: 10.1002/eqe.2974
       
  • A probabilistic framework for estimating the residual drift of idealized
           SDOF systems of non-degrading conventional and damped structures
    • Authors: Jack Wen Wei Guo; Constantin Christopoulos
      Abstract: This paper presents a general framework for predicting the residual drift of idealized SDOF systems that can be used to represent non-degrading structures, including those with supplemental dampers. The framework first uses post-peak oscillation analysis to predict the maximum ratio of residual displacement to the peak transient displacement in a random sample. Then, residual displacement ratios obtained from nonlinear time-history analyses using both farfield and near-fault-pulse records were examined to identify trends, which were explained using the oscillation mechanics of SDOF systems. It is shown that large errors can result in existing probability models that do not capture the influence of key parameters on the residual displacement. Building on the observations that were made, a general probability distribution for the ratio of residual displacement to the peak transient displacement that more accurately reflects the physical bounds obtained from post-peak oscillation analysis is proposed for capturing the probabilistic residual displacement response of these systems. The proposed distribution is shown to be more accurate when compared with previously proposed distributions in the literature due to its explicit account of dynamic and damping properties, which have a significant impact on the residual displacement. This study provides a rational basis for further development of a residual drift prediction tool for the performance-based design and analysis of more complex multi-degree-of-freedom systems.
      PubDate: 2017-09-14T02:51:44.79386-05:0
      DOI: 10.1002/eqe.2975
       
  • Computational simulation of slab vibration and horizontal-vertical
           coupling in a full-scale test bed subjected to 3D shaking at E-Defense
    • Authors: Jean C. Guzman Pujols; Keri L. Ryan
      Abstract: This paper focuses on slab vibration and a horizontal-vertical coupling effect observed in a full-scale 5-story moment frame test bed building in 2 configurations: isolated with a hybrid combination of lead-rubber bearings and cross-linear (rolling) bearings, and fixed at the base. Median peak slab vibrations were amplified—relative to the peak vertical shake table accelerations—by factors ranging from 2 at the second floor to 7 at the roof, and horizontal floor accelerations were significantly amplified during 3D (combined horizontal and vertical) motions compared with 2D (horizontal only) motions of comparable input intensity. The experimentally observed slab accelerations and the horizontal-vertical coupling effect were simulated through a 3D model of the specimen using standard software and modeling assumptions. The floor system was modeled with frame elements for beams/girders and shell elements for floor slabs; the insertion point method with end joint offsets was used to represent the floor system composite behavior, and floor mass was finely distributed through element discretization. The coupling behavior was partially attributed to the asymmetry of the building that was intensified by asymmetrically configured supplemental mass at the roof. Horizontal-vertical coupled modes were identified through modal analysis and verified with evaluation of floor spectral peaks.
      PubDate: 2017-09-06T23:02:44.559423-05:
      DOI: 10.1002/eqe.2973
       
  • Influence of deterioration modelling on the seismic response of steel
           moment frames designed to Eurocode 8
    • Authors: Antonios Tsitos; Miguel A. Bravo-Haro, Ahmed Y. Elghazouli
      Abstract: This paper assesses the influence of cyclic and in-cycle degradation on seismic drift demands in moment-resisting steel frames (MRF) designed to Eurocode 8. The structural characteristics, ground motion frequency content, and level of inelasticity are the primary parameters considered. A set of single-degree-of-freedom (SDOF) systems, subjected to varying levels of inelastic demands, is initially investigated followed by an extensive study on multi-storey frames. The latter comprises a large number of incremental dynamic analyses (IDA) on 12 frames modelled with or without consideration of degradation effects. A suite of 56 far-field ground motion records, appropriately scaled to simulate 4 levels of inelastic demand, is employed for the IDA. Characteristic results from a detailed parametric investigation show that maximum response in terms of global and inter-storey drifts is notably affected by degradation phenomena, in addition to the earthquake frequency content and the scaled inelastic demands. Consistently, both SDOF and frame systems with fundamental periods shorter than the mean period of ground motion can experience higher lateral strength demands and seismic drifts than those of non-degrading counterparts in the same period range. Also, degrading multi-storey frames can exhibit distinctly different plastic mechanisms with concentration of drifts at lower levels. Importantly, degrading systems might reach a “near-collapse” limit state at ductility demand levels comparable to or lower than the assumed design behaviour factor, a result with direct consequences on optimised design situations where over-strength would be minimal. Finally, the implications of the findings with respect to design-level limit states are discussed.
      PubDate: 2017-09-06T23:01:44.179919-05:
      DOI: 10.1002/eqe.2954
       
  • Integrating visual damage simulation, virtual inspection, and collapse
           capacity to evaluate post-earthquake structural safety of buildings
    • Authors: Henry V. Burton; Gregory G. Deierlein
      Abstract: A methodology is introduced to assess the post-earthquake structural safety of damaged buildings using a quantitative relationship between observable structural component damage and the change in collapse vulnerability. The proposed framework integrates component-level damage simulation, virtual inspection, and structural collapse performance assessment. Engineering demand parameters from nonlinear response history analyses are used in conjunction with component-level damage simulation to generate multiple realizations of damage to key structural elements. Triggering damage state ratios, which describe the fraction of components within a damage state that results in an unsafe placard assignment, are explicitly linked to the increased collapse vulnerability of the damaged building. A case study is presented in which the framework is applied to a 4-story reinforced concrete frame building with masonry infills. The results show that when subjected to maximum considered earthquake level ground motions, the probability of experiencing enough structural damage to trigger an unsafe placard, leading to building closure, is more than 2 orders of magnitude higher than the risk of collapse.
      PubDate: 2017-09-06T23:01:09.409794-05:
      DOI: 10.1002/eqe.2951
       
  • Parameter identification for on-line model updating in hybrid simulations
           using a gradient-based method
    • Authors: Ming-Chieh Chuang; Shang-Hsien Hsieh, Keh-Chyuan Tsai, Chao-Hsien Li, Kung-Juin Wang, An-Chien Wu
      Abstract: To improve the efficiency of model fitting, parameter identification techniques have been actively investigated. Recently, the applications of parameter identification migrated from off-line model fitting to on-line model updating. The objective of this study is to develop a gradient-based method for model updating to advance hybrid simulation also called hybrid test. A novel modification of the proposed method, which can reduce the number of design variables to improve the identification efficiency, is illustrated in detail. To investigate the model updating, simulated hybrid tests were conducted with a 5-story steel frame equipped with buckling-restrained braces (BRBs) utilized in the shaking table tests conducted in E-Defense in Japan in 2009. The calibrated analytical model that was verified with the test results can serve as the reference model. In the simulated hybrid tests, the physical BRB substructure is numerically simulated by utilizing a truss element with the 2-surface model identical to the part of the reference model. Such numerical verification allows simulation of measurement errors for investigation on the performance of the proposed method. Moreover, the feasibility of sharing the identified parameter values, which were obtained from the physical substructure responses, with the relevant numerical models is also verified with the artificial component responses derived from the physical experiments.
      PubDate: 2017-08-30T21:13:04.834275-05:
      DOI: 10.1002/eqe.2950
       
  • A damage model for structures with degrading response
    • Authors: Thanh. N. Do; Filip. C. Filippou
      Abstract: The paper presents a hysteretic damage model for the response simulation of structural components with strength and stiffness deterioration under cyclic loading. The model is based on 1D continuum damage mechanics and relates any 2 work-conjugate response variables such as force-displacement, moment-rotation, or stress-strain. The strength and stiffness deterioration is described by a continuous damage variable. The formulation uses a criterion based on the hysteretic energy and the maximum or minimum deformation for damage initiation with a cumulative probability distribution function for the damage evolution. A series of structural component response simulations showcase the ability of the model to describe different types of hysteretic behavior. The relation of the model's damage variable to the Park-Ang damage index is also discussed. Because of its consistent and numerically robust formulation, the model is suitable for the large-scale seismic response simulation of structural systems with strength and stiffness deterioration.
      PubDate: 2017-08-30T21:12:35.001297-05:
      DOI: 10.1002/eqe.2952
       
  • A site-consistent method to quantify sufficiency of alternative IMs in
           relation to PSDA
    • Authors: Somayajulu L. N. Dhulipala; Adrian Rodriguez-Marek, Shyam Ranganathan, Madeleine M. Flint
      Abstract: In probabilistic seismic demand analysis, evaluation of the sufficiency of an intensity measure (IM) is an important criterion to avoid biased assessment of the demand hazard. However, there exists no metric to quantify the degree of sufficiency as per the criterion of Luco and Cornell (2007). This paper proposes a site-specific unified measure for degree of sufficiency from all seismological parameters under consideration using a total information gain metric. This unified metric for sufficiency supports not only comparison of the performance of different IMs given a response quantity but also assessment of the performance of a particular IM across different response quantities. The proposed sufficiency metric was evaluated for a 4-story steel moment frame building, and the influence of ground motion selection on the degree of sufficiency was investigated. It was observed that ground motion selection can have a significant impact on IM sufficiency. Because computing the total information gain requires continuous deaggregation across the IM space, an approximate deaggregation technique that allows for a more practical estimation of marginal deaggregation probabilities is proposed. It is expected that the total information gain metric proposed in this paper will aid in understanding the efficiency-sufficiency relation, thus enabling the selection of a proper scalar IM for a given site and application in probabilistic seismic demand analysis.
      PubDate: 2017-08-30T21:11:26.01603-05:0
      DOI: 10.1002/eqe.2955
       
  • Earthquake-induced structural response output-only identification by two
           different Operational Modal Analysis techniques
    • Authors: Fabio Pioldi; Egidio Rizzi
      Abstract: Output-only system identification is developed here towards assessing current modal dynamic properties of buildings under seismic excitation. Earthquake-induced structural response signals are adopted as input channels for two different Operational Modal Analysis (OMA) techniques, namely, a refined Frequency Domain Decomposition (rFDD) algorithm and an improved Data-Driven Stochastic Subspace Identification (SSI-DATA) procedure. Despite that short-duration, non-stationary, earthquake-induced structural response signals shall not fulfil traditional OMA assumptions, these implementations are specifically formulated to operate with seismic responses and simultaneous heavy damping (in terms of identification challenge), for a consistent estimation of natural frequencies, mode shapes, and modal damping ratios. A linear ten-storey frame structure under a set of ten selected earthquake base-excitation instances is numerically simulated, by comparing the results from the two identification methods. According to this study, best up-to-date, reinterpreted OMA techniques may effectively be used to characterize the current dynamic behaviour of buildings, thus allowing for potential Structural Health Monitoring approaches in the Earthquake Engineering range.
      PubDate: 2017-08-30T02:11:50.017358-05:
      DOI: 10.1002/eqe.2947
       
  • Seismic retrofit of low-rise steel buildings in Canada using rocking steel
           braced frames
    • Authors: Paul Mottier; Robert Tremblay, Colin Rogers
      Abstract: This article examines the use of rocking steel braced frames for the retrofit of existing seismically deficient steel building structures. Rocking is also used to achieve superior seismic performance to reduce repair costs and disruption time after earthquakes. The study focuses on low-rise buildings for which re-centring is solely provided by gravity loads rather than added post-tensioning elements. Friction energy dissipative (ED) devices are used to control drifts. The system is applied to 2-storey and 3-storey structures located in 2 seismically active regions of Canada. Firm ground and soft soil conditions are considered. The seismic performance of the retrofit scheme is evaluated using nonlinear dynamic analysis and ASCE 41-13. For all structures, rocking permits to achieve immediate occupancy performance under 2% in 50 years seismic hazard if the braces and their connections at the building's top storeys are strengthened to resist amplified forces due to higher mode response. Base shears are also increased due to higher modes. Impact at column bases upon rocking induces magnified column forces and vertical response in the gravity system. Friction ED is found more effective for drift control than systems with ring springs or bars yielding in tension. Drifts are sufficiently small to achieve position retention performance for most nonstructural components. Horizontal accelerations are generally lower than predicted from ASCE 41 for regular nonrocking structures. Vertical accelerations in the gravity framing directly connected to the rocking frame are however higher than those predicted for ordinary structures. Vertical ground motions have limited effect on frame response.
      PubDate: 2017-08-30T02:11:24.86681-05:0
      DOI: 10.1002/eqe.2953
       
  • An approach for shake table performance evaluation during repair and
           retrofit actions
    • Authors: Christopher Trautner; Yewei Zheng, John S. McCartney, Tara Hutchinson
      Abstract: Large-scale, servo-hydraulic shake tables are a central fixture of many earthquake engineering and structural dynamics laboratories. Wear and component failure from frequent use may lead to control problems resulting in reduced motion fidelity, necessitating repairs and replacement of major components. This paper presents a methodology to evaluate shake table performance pre- and post-repair, including the definition of important performance metrics. The strategy suggested is presented in the context of the rebuilding of a 4.9 × 3.1 m, 350-kN-capacity uniaxial shake table. In this case, the rebuild consisted of characterization of wear to table components, replacement of worn bearing surfaces, and replacement of hydraulic accumulators. To assess the effectiveness of the repair actions, sinusoidal and triangular waves, white noise, and earthquake histories were run on the table before and after the rebuild. The repair actions were successful in reducing the position and velocity dependence of friction, improving the ability of control algorithms to accurately reproduce earthquake motions. The maximum and average response spectral misfits in the period range of 0.1–2 seconds were reduced from approximately 50% to 15%, and from 5% to less than 2.5%, respectively.
      PubDate: 2017-08-22T23:20:30.19601-05:0
      DOI: 10.1002/eqe.2942
       
  • Sensitivity analysis of pounding between adjacent structures
    • Authors: Vincent Crozet; Ioannis Politopoulos, Mingguan Yang, Jean-Marc Martinez, Silvano Erlicher
      Abstract: This article deals with sensitivity of the response of pounding buildings with respect to structural and earthquake excitation parameters. A comprehensive sensitivity analysis is carried out by means of Monte Carlo simulations of adjacent single degree of freedom impacting oscillators. This sensitivity analysis, based on Sobol's method, computes sensitivity indexes which provide a consistent measure of the relative importance of parameters such as the dimensionless main excitation frequency, the mass and frequency ratios of the structures, and the coefficient of restitution. Moreover, the influence of nonlinear behavior of the impacting structures is also considered. The consequences of pounding on the structures themselves are analyzed in terms of maximum force and nonlinear demand amplification compared with the case without pounding. As for the influence of pounding on the floor response spectra, the quantity of interest is the maximum impact impulse. The overall conclusions of this analysis are that the frequency ratio is the most important parameter as far as the maximum force and nonlinear demand are concerned. Regarding the maximum impact impulse, the mass and frequency ratios are, in general, the most influential parameters, the mass ratio being predominant for low frequencies of the oscillator of interest.
      PubDate: 2017-08-17T21:16:02.521748-05:
      DOI: 10.1002/eqe.2949
       
  • Design of transverse reinforcement to avoid premature buckling of main
           bars
    • Authors: Rajesh Prasad Dhakal; Junsheng Su
      Abstract: This paper proposes an enhancement to the current strength and confinement-based design of transverse reinforcement in rectangular and circular reinforced concrete members to ensure that the flexural strength of reinforced concrete sections does not degrade excessively due to buckling of longitudinal bars until the desired level of plastic deformation is achieved. Antibuckling design criteria are developed based on a popular bar buckling model that uses a bar buckling parameter (combining the bar diameter, yield strength, and buckling length) to solely describe the bar buckling behavior. The value of buckling parameter that limits the buckling-induced stress loss to 15% in compression bars at the strain corresponding to the design ductility is determined. For a bar of known diameter and yield strength, the maximum allowable buckling length can then be determined, which serves as the maximum limit for the tie/stirrup/hoop spacing. Lateral stiffness required to restrain the buckling tendency of main bars at the locations of the ties/stirrups/hoops depends on the flexural rigidity of the main bars and the buckling length (equal to or multiple of tie/hoop/stirrup spacing), whereas the antibuckling stiffness (ie, resistance) provided by the ties/stirrups/hoops depends on their size, number, and arrangement. Using the above concept, design recommendations for the amount, arrangement, and spacing of rectangular and circular ties/stirrups/hoops are then established to ensure that the antibuckling stiffness of the provided transverse reinforcement is greater than the stiffness required to restrain the buckling-prone main bars. Key aspects of the developed method are verified using experimental tests from literature.
      PubDate: 2017-08-15T21:16:32.679689-05:
      DOI: 10.1002/eqe.2944
       
  • A new model for spectral velocity ordinates at long periods
    • Authors: Nikhil Samdaria; Vinay K. Gupta
      Abstract: The estimation of peak linear response via elastic design (response) spectra continues to form the basis of earthquake-resistant design of structural systems in various codes of practice all over the world. Many response spectrum-based formulations of peak linear response require an additional input of the spectral velocity (SV) ordinates consistent with the specified seismic hazard. SV ordinates have been conventionally approximated by pseudo spectral velocity (PSV) ordinates, which are close to the SV ordinates only over the intermediate frequency range coinciding with the velocity-sensitive region. At long periods, PSV ordinates underestimate the SV ordinates, and this study proposes a formulation of a correction factor (>1) that needs to be multiplied by the PSV ordinates in order to close the gap between the two sets of ordinates. A simple model is proposed in the form of a power function in oscillator period to estimate this factor in terms of two governing parameters which are in turn estimated from two single-parameter scaling equations. The parameters considered for the scaling equations are (1) the period at which the PSV spectrum is maximized and (2) the rate of decay of the pseudo spectral acceleration (PSA) amplitudes at long periods. For a given damping ratio, four regression coefficients are determined for the scaling equations with the help of 205 ground motions recorded in western USA. A numerical study undertaken with the help of several design PSA spectra and ensembles of spectrum-compatible ground motions illustrates the effectiveness of the proposed correction factor, together with the proposed scaling models, in comparison with the PSV approximation in a variety of design situations. Both the input parameters mentioned above can be easily obtained from the specified design spectrum, and thus the proposed model is convenient to use.
      PubDate: 2017-08-14T23:11:13.074079-05:
      DOI: 10.1002/eqe.2945
       
  • On the treatment of uncertainty in seismic vulnerability and portfolio
           risk assessment
    • Authors: Luis Sousa; Vitor Silva, Mário Marques, Helen Crowley
      Abstract: In a related study developed by the authors, building fragility is represented by intensity-specific distributions of damage exceedance probability of various damage states. The contribution of the latter has been demonstrated in the context of loss estimation of building portfolios, where it is shown that the proposed concept of conditional fragility functions provides the link between seismic intensity and the uncertainty in damage exceedance probabilities. In the present study, this methodology is extended to the definition of building vulnerability, whereby vulnerability functions are characterized by hazard-consistent distributions of damage ratio per level of primary seismic intensity parameter—Sa(T1). The latter is further included in a loss assessment framework, in which the impact of variability and spatial correlation of damage ratio in the probabilistic evaluation of seismic loss is accounted for, using test-bed portfolios of 2, 5, and 8-story precode reinforced concrete buildings located in the district of Lisbon, Portugal. This methodology is evaluated in comparison with current state-of-the-art methods of vulnerability and loss calculation, highlighting the discrepancies that can arise in loss estimates when the variability and spatial distributions of damage ratio, influenced by ground motion properties other than the considered primary intensity measure, are not taken into account.
      PubDate: 2017-08-09T21:31:25.03775-05:0
      DOI: 10.1002/eqe.2940
       
  • Empirical evaluation of peak ground velocity and displacement as a
           function of elastic spectral ordinates for design
    • Authors: Roberto Paolucci; Chiara Smerzini
      Abstract: In the framework of the revision of Part 1 of Eurocode 8, this study aims at developing new empirical correlations to compute peak values of ground velocity (PGV) and displacement (PGD) as a function of elastic spectral ordinates for design. At variance with the expressions for PGV and PGD currently adopted in the Eurocode 8, based solely on the peak ground acceleration (PGA), in this paper reference is made to spectral ordinates of the short and intermediate period range, namely Ss, which is the constant acceleration spectral ordinate, and S1, which is the spectral ordinate at 1 s. On the one hand, a relationship between PGV and the product (Ss⋅S1) was found based on the regression analysis on a high-quality strong-motion dataset. On the other hand, the PGD was estimated by extrapolating to long periods the constant displacement branch of the elastic response spectrum, introducing a correlation between the corner period TD and S1. For this purpose, results of a long period probabilistic seismic hazard assessment study for Italy, encompassing low to high seismicity areas, were considered. Furthermore, verification of the proposed relationship against strong-motion records was carried out, and differences justified in terms of the concept of uniform hazard spectrum.
      PubDate: 2017-08-09T21:30:45.927364-05:
      DOI: 10.1002/eqe.2943
       
  • Conditional spectrum based ground motion record selection using average
           spectral acceleration
    • Authors: Mohsen Kohrangi; Paolo Bazzurro, Dimitrios Vamvatsikos, Andrea Spillatura
      PubDate: 2017-08-09T21:30:24.769488-05:
      DOI: 10.1002/eqe.2946
       
  • Design and full-scale experimental evaluation of a seismically endurant
           steel buckling-restrained brace system
    • Authors: Morteza Dehghani; Robert Tremblay
      Abstract: This paper presents the results of 12 full-scale tests on buckling-restrained brace (BRB) specimens. A simple-to-fabricate all-steel encasing joined by high-strength bolts was used as the buckling-restrainer mechanism. Steel BRBs offer significant energy dissipation capability through nondeteriorating inelastic response of an internal ductile core. However, seismic performance of BRBs is characterized by interaction between several factors. In this experimental study, the effects of core-restrainer interfacial condition, gap size, loading history, bolt spacing, and restraining capacity are evaluated. A simple hinge detail is introduced at the brace ends to reduce the flexural demand on the framing components. Tested specimens with bare steel contact surfaces exhibited satisfactory performance under the American Institute of Steel Construction qualification test protocol. The BRBs with friction-control self-adhesive polymer liners and a graphite-based dry lubricant displayed larger cumulative inelastic ductility under large-amplitude cyclic loading, exceeding current code minimum requirements. The BRB system is also examined under repeated fast-rate seismic deformation history. This system showed significant ductility capacity and remarkable endurance under dynamic loading. Furthermore, performance is qualified under long-duration loading history from subduction zone's megathrust type of earthquake. Predictable and stable performance of the proposed hinge detail was confirmed by the test results. Internally imposed normal thrust on the restrainer is measured using series of instrumented bolts. Weak- and strong-axis buckling responses of the core are examined. Higher post-yield stiffness was achieved when the latter governed, which could be advantageous to the overall seismic response of braced frames incorporating BRBs.
      PubDate: 2017-07-30T23:52:21.802846-05:
      DOI: 10.1002/eqe.2941
       
  • System identification and modeling of a dynamically tested and gradually
           damaged 10-story reinforced concrete building
    • Authors: Seyedsina Yousefianmoghadam; Iman Behmanesh, Andreas Stavridis, Babak Moaveni, Amin Nozari, Andrea Sacco
      Abstract: This paper discusses the dynamic tests, system identification, and modeling of a 10-story reinforced concrete building. Six infill walls were demolished in 3 stages during the tests to introduce damage. In each damage stage, dynamic tests were conducted by using an eccentric-mass shaker. Accelerometers were installed to record the torsional and translational responses of the building to the induced excitation, as well as its ambient vibration. The modal properties in all damage states are identified using 2 operational modal analysis methods that can capture the effect of the wall demolition. The modal identification is facilitated by a finite element model of the building. In turn, the model is validated through the comparison of the numerically and experimentally obtained modal parameters. The validated model is used in a parametric study to estimate the influence of structural and nonstructural elements on the dynamic properties of the building and to assess the validity of commonly used empirical formulas found in building codes. Issues related to the applicability and feasibility of system identification on complex structures, as well as considerations for the development of accurate, yet efficient, finite element models are also discussed.
      PubDate: 2017-07-27T23:22:03.813516-05:
      DOI: 10.1002/eqe.2935
       
  • Rocking bodies with arbitrary interface defects: Analytical development
           and experimental verification
    • Authors: C.E. Wittich; T.C. Hutchinson
      Abstract: The rocking response of a rigid, freestanding block in two dimensions typically assumes perfect contact at the base of the block with instantaneous impacts at two distinct, symmetric rocking points. This paper extends the classical two-dimensional rocking model to account for an arbitrary number of rocking points at the base representing geometric interface defects. The equations of motion of this modified rocking system are derived and presented in general terms. Energy dissipation is modeled assuming instantaneous point impacts, yielding a discrete angular velocity adjustment. Whereas this factor is always less than unity in the classical model, it is possible for this factor to exceed unity in the presented model, yielding a finite increase in the angular velocity at impact and a markedly different rotational response than the classical model predicts. The derived model and the classical model are numerically integrated and compared to the results of recent shake table tests. These comparisons show that the new model significantly enhances agreement in both peak angular displacement and motion decay. The equations of motion and the energy dissipation of the presented model are further investigated parametrically considering the size of the defect, the number of rocking points, and the aspect ratio and size of the block.
      PubDate: 2017-07-27T23:20:42.480783-05:
      DOI: 10.1002/eqe.2937
       
  • Seismic risk assessment of liquid storage tanks via a nonlinear surrogate
           model
    • Authors: Konstantinos Bakalis; Dimitrios Vamvatsikos, Michalis Fragiadakis
      Abstract: A performance-based earthquake engineering approach is developed for the seismic risk assessment of fixed-roof atmospheric steel liquid storage tanks. The proposed method is based on a surrogate single-mass model that consists of elastic beam-column elements and nonlinear springs. Appropriate component and system-level damage states are defined, following the identification of commonly observed modes of failure that may occur during an earthquake. Incremental dynamic analysis and simplified cloud are offered as potential approaches to derive the distribution of response parameters given the seismic intensity. A parametric investigation that engages the aforementioned analysis methods is conducted on 3 tanks of varying geometry, considering both anchored and unanchored support conditions. Special attention is paid to the elephant's foot buckling formation, by offering extensive information on its capacity and demand representation within the seismic risk assessment process. Seismic fragility curves are initially extracted for the component-level damage states, to compare the effect of each analysis approach on the estimated performance. The subsequent generation of system-level fragility curves reveals the issue of nonsequential damage states, whereby significant damage may abruptly appear without precursory lighter damage states.
      PubDate: 2017-07-25T23:46:05.58175-05:0
      DOI: 10.1002/eqe.2939
       
  • Finite element analysis of damage and failure of reinforced concrete
           members under earthquake loading
    • Authors: Mohammadreza Moharrami; Ioannis Koutromanos
      Abstract: This paper presents a three-dimensional analysis framework, based on the explicit finite element method, for the simulation of reinforced concrete components under cyclic static and dynamic loading. A recently developed triaxial constitutive model for concrete is combined with a material model for reinforcing steel which can account for rupture due to low-cycle fatigue. The reinforcing bars are represented with geometrically nonlinear beam elements to account for buckling of the reinforcement. The strain penetration effect is also accounted for in the models. The modeling scheme is used in a commercial finite element program and validated with the results of experimental static and dynamic tests on reinforced concrete columns and walls. The analyses are supplemented with a parametric study to investigate the impact of several modeling assumptions on the obtained results.
      PubDate: 2017-07-20T00:08:37.140107-05:
      DOI: 10.1002/eqe.2932
       
  • A numerical study on the cumulative out-of-plane damage to church masonry
           façades due to a sequence of strong ground motions
    • Authors: Siro Casolo
      Abstract: Seismic shocks occur sometimes as a sequence, close in space and time, of destructive events of comparable intensity. In these cases, a significant portion of the damage to historical buildings can be related with the cumulated damage on structures that become progressively more vulnerable. This research investigates the specific increase of damage determined by a sequence of strong ground motions, focusing the interest on the out-of-plane response of 2 church masonry façades. The dynamic analyses were performed by a specific rigid body and spring model RBSM, which only accounts for out-of-plane damage mechanisms. Two idealized models of façade, each made of 2 different masonry bonds, have been studied by applying various sequences of recorded accelerograms. The results highlighted a complex relationship between the spectral content of the seismic shocks and the characteristics of the structures that change in the course of the loading sequence due to the development of damage. The Housner spectral intensity proved to be a reliable scalar measure of the ground motion destructiveness for these façades. Moreover, when considering a design-consistent accelerogram that causes a relevant damage pattern, ie, with a significant elongation of the effective first period of vibration, the numerical results indicated a possible spectral intensity threshold below which the occurrence of repeated seismic shocks, both before and after the reference design shock, can be considered as irrelevant. On the other hand, a catastrophic increase of damage should be expected when this threshold is overcome.
      PubDate: 2017-07-14T00:22:39.464152-05:
      DOI: 10.1002/eqe.2927
       
  • Fragility functions for masonry infill walls with in-plane loading
    • Authors: Andrea Chiozzi; Eduardo Miranda
      Abstract: Recent seismic events have provided evidence that damage to masonry infills can lead not only to large economic losses but also to significant injuries and even fatalities. The estimation of damage of such elements and the corresponding consequences within the performance-based earthquake engineering framework requires the construction of reliable fragility functions. In this paper, drift-based fragility functions are developed for in-plane loaded masonry infills, derived from a comprehensive experimental data set gathered from current literature, comprising 152 masonry infills with different geometries and built with different types of masonry blocks, when tested under lateral cyclic loading. Three damage states associated with the structural performance and reparability of masonry infill walls are defined. The effect of mortar compression strength, masonry prism compression strength, and presence of openings is evaluated and incorporated for damage states where their influence is found to be statistically significant. Uncertainty due to specimen-to-specimen variability and sample size is quantified and included in the proposed fragility functions. It is concluded that prism strength and mortar strength are better indicators of the fragility of masonry infills than the type of bricks/blocks used, whose influence, in general, is not statistically significant for all damage states. Finally, the presence of openings is also shown to have statistically relevant impact on the level of interstory drift ratio triggering the lower damage states.
      PubDate: 2017-07-14T00:22:08.82127-05:0
      DOI: 10.1002/eqe.2934
       
  • Nonlinear FE model updating and reconstruction of the response of an
           instrumented seismic isolated bridge to the 2010 Maule Chile earthquake
    • Authors: Yong Li; Rodrigo Astroza, Joel P. Conte, Pedro Soto
      Abstract: Nonlinear finite element (FE) modeling has been widely used to investigate the effects of seismic isolation on the response of bridges to earthquakes. However, most FE models of seismic isolated bridges (SIB) have used seismic isolator models calibrated from component test data, while the prediction accuracy of nonlinear FE models of SIB is rarely addressed by using data recorded from instrumented bridges. In this paper, the accuracy of a state-of-the-art FE model is studied through nonlinear FE model updating (FEMU) of an existing instrumented SIB, the Marga-Marga Bridge located in Viña del Mar, Chile. The seismic isolator models are updated in 2 phases: component-wise and system-wise FEMU. The isolator model parameters obtained from 23 isolator component tests show large scatter, and poor goodness of fit of the FE-predicted bridge response to the 2010 Mw 8.8 Maule, Chile Earthquake is obtained when most of those parameter sets are used for the isolator elements of the bridge model. In contrast, good agreement is obtained between the FE-predicted and measured bridge response when the isolator model parameters are calibrated using the bridge response data recorded during the mega-earthquake. Nonlinear FEMU is conducted by solving single- and multiobjective optimization problems using high-throughput cloud computing. The updated FE model is then used to reconstruct response quantities not recorded during the earthquake, gaining more insight into the effects of seismic isolation on the response of the bridge during the strong earthquake.
      PubDate: 2017-07-12T22:16:23.421551-05:
      DOI: 10.1002/eqe.2925
       
  • Modification of stochastic ground motion models for matching target
           intensity measures
    • Authors: Alexandra Tsioulou; Alexandros A. Taflanidis, Carmine Galasso
      Abstract: Stochastic ground motion models produce synthetic time-histories by modulating a white noise sequence through functions that address spectral and temporal properties of the excitation. The resultant ground motions can be then used in simulation-based seismic risk assessment applications. This is established by relating the parameters of the aforementioned functions to earthquake and site characteristics through predictive relationships. An important concern related to the use of these models is the fact that through current approaches in selecting these predictive relationships, compatibility to the seismic hazard is not guaranteed. This work offers a computationally efficient framework for the modification of stochastic ground motion models to match target intensity measures (IMs) for a specific site and structure of interest. This is set as an optimization problem with a dual objective. The first objective minimizes the discrepancy between the target IMs and the predictions established through the stochastic ground motion model for a chosen earthquake scenario. The second objective constraints the deviation from the model characteristics suggested by existing predictive relationships, guaranteeing that the resultant ground motions not only match the target IMs but are also compatible with regional trends. A framework leveraging kriging surrogate modeling is formulated for performing the resultant multi-objective optimization, and different computational aspects related to this optimization are discussed in detail. The illustrative implementation shows that the proposed framework can provide ground motions with high compatibility to target IMs with small only deviation from existing predictive relationships and discusses approaches for selecting a final compromise between these two competing objectives.
      PubDate: 2017-07-09T23:25:57.686692-05:
      DOI: 10.1002/eqe.2933
       
  • Choice between series and parallel connections of hysteretic system and
           viscous damper for seismic protection of structures
    • Authors: Youness Bougteb; Tathagata Ray
      Abstract: Supplemental viscous damping devices are generally envisioned to be connected in parallel to the inelastic parent structure or hysteretic damping devices. This gives rise to higher base shear, and often greater ductility demand of the hysteretic system. The series connection of the viscous and hysteretic system (the inelastic structure or a damper) is an alternative approach. In this paper, comparisons between the series and parallel connections of the hysteretic system and viscous dampers are done through response spectra analyses of single degree of freedom structures. Ductility demand of the hysteretic system and the total base shear are chosen as the response quantities. For the series model, a semi-implicit solution scheme for classical Maxwell model is modified to include the inelasticity of the time-independent hysteretic spring. It is observed that the series connection of the 2 dampers gives lower base shear than does the parallel connection. For long-period and low-damping structures, the ductility demand of the hysteretic system in series connection is higher than that in parallel connection. Increasing the viscous damping in series connection reduces the ductility demand substantially, lower than that obtained in parallel connection. Practical methods for implementing the series and parallel connections, in line with roof isolation, are also suggested.
      PubDate: 2017-07-06T23:17:37.938762-05:
      DOI: 10.1002/eqe.2938
       
  • Improved risk-targeted performance-based seismic design of reinforced
           concrete frame structures
    • Authors: Paolo Franchin; Francesco Petrini, Fabrizio Mollaioli
      Abstract: This paper presents a procedure for seismic design of reinforced concrete structures, in which performance objectives are formulated in terms of maximum accepted mean annual frequency (MAF) of exceedance, for multiple limit states. The procedure is explicitly probabilistic and uses Cornell's like closed-form equations for the MAFs. A gradient-based constrained optimization technique is used for obtaining values of structural design variables (members' section size and reinforcement) satisfying multiple objectives in terms of risk levels. The method is practically feasible even for real-sized structures thanks to the adoption of adaptive equivalent linear models where element-by-element stiffness reduction is performed (2 linear analyses per intensity level). General geometric and capacity design constraints are duly accounted for. The procedure is applied to a 15-storey plane frame building, and validation is conducted against results in terms of drift profiles and MAF of exceedance, obtained by multiple-stripe analysis with records selected to match conditional spectra. Results show that the method is suitable for performance-based seismic design of RC structures with explicit targets in terms of desired risk levels.
      PubDate: 2017-07-06T04:01:37.198434-05:
      DOI: 10.1002/eqe.2936
       
  • Analytical model for the out-of-plane response of vertically spanning
           unreinforced masonry walls
    • Authors: Michele Godio; Katrin Beyer
      Abstract: An analytical model describing the flexural response of vertically spanning out-of-plane loaded unreinforced masonry walls is presented in this paper. The model is based on the second-order Euler-Bernoulli beam theory and captures important characteristics of the out-of-plane response of masonry walls that have been observed in experimental tests and from numerical studies but for which an analytical solution was still lacking: the onset and the evolution of cracking, the peak strength of the out-of-plane loaded walls, and the softening of the response due to P−Δ effects. The model is validated against experimental results, and the comparison shows that the model captures both the prepeak and postpeak response of the walls. From the analytical model of the force-displacement curve, a formula for the maximum out-of-plane strength of the walls is derived, which can be directly applied in engineering practice.
      PubDate: 2017-07-06T04:00:58.900072-05:
      DOI: 10.1002/eqe.2929
       
  • IM-based and EDP-based decision models for the verification of the seismic
           collapse safety of buildings
    • Authors: Matjaž Dolšek; Nuša Lazar Sinković, Jure Žižmond
      Abstract: Decision models for the verification of seismic collapse safety of buildings are introduced. The derivations are based on the concept of the acceptable (target) annual probability of collapse, whereas the decision making involves comparisons between seismic demand and capacity, which is familiar to engineering practitioners. Seismic demand, which corresponds to the design seismic action associated with a selected return period, can be expressed either in terms of an intensity measure (IM) or an engineering demand parameter (EDP). Seismic capacity, on the other hand, is defined by dividing the near-collapse limit-state IM or EDP by an appropriate risk-targeted safety factor (γim or γedp), which is the only safety factor used in the proposed decision model. Consequently, the seismic performance assessment of a building should be based on the best possible estimate. For a case study, it is shown that if the target collapse risk is set to 10−4 (0.5% over a period of 50 years), and if the seismic demand corresponds to a return period of 475 years (10% over a period of 50 years), then it can be demonstrated that γim is approximately equal to 2.5 for very stiff buildings, whereas for buildings with long periods the value of γim can increase up to a value of approximately 5. The model using γedp is equal to that using γim only if it can be assumed that displacements, with consideration of nonlinear behavior, are equal to displacements from linear elastic analysis.
      PubDate: 2017-06-29T22:41:09.43734-05:0
      DOI: 10.1002/eqe.2923
       
  • Methodology for practical seismic assessment of unreinforced masonry
           buildings with historical value
    • Authors: Stylianos I. Pardalopoulos; Stavroula J. Pantazopoulou
      Abstract: Historical constructions are part of the world heritage, and their survival is an important priority. Comprising mostly unreinforced, load-bearing masonry, heritage buildings may date anywhere from antiquity to the 19th and early 20th century. Being exposed to the elements over the years, they are in various states of disrepair and material degradation. Based on postearthquake reconnaissance reports, these structures occasionally behave rather poorly, even in moderate seismic events, undergoing catastrophic damage and collapse, whereas retrofitting is governed by international conventions regarding noninvasiveness and reversibility of the intervention. The complexity of their structural systems (continuous structural components, lack of diaphragm action, material brittleness, and variability) challenges the established methods of condition assessment of preretrofitted and postretrofitted heritage constructions. The most advanced state of the art in materials and analysis tools is required, far more complex than with conventional buildings. Thus, an assessment procedure specifically geared to this class of structures is urgently needed, in order to assist engineers in this endeavor. The objective of this paper is the development of a performance-based assessment framework that is palatable to practitioners and quite accurate in seismic assessment of unreinforced masonry buildings with no diaphragm action. The underlying theoretical background of the method is illustrated with reference to first principles: global demand is obtained from the design earthquake scenario for the region, using empirical estimates for the prevailing translational period of the system; deformation demands are localized using an approximation to the translational 3-D shape of lateral response, estimated using a uniform gravitational field in the direction of action of the earthquake; acceptance criteria are specified in terms of relative drift ratios, referring to the in-plane and the out-of-plane action of the masonry piers. The quantitative accuracy of the introduced procedure is evaluated through comparison with detailed time-history dynamic analysis results, using a real life example case study. Qualitative relevance of the results is evaluated through comparison of the location and extent of anticipated damage estimated from the proposed assessment procedure, with reported records of the building damages that occurred during a significant past earthquake event.
      PubDate: 2017-06-28T02:46:29.659333-05:
      DOI: 10.1002/eqe.2931
       
  • Analytical fragility assessment using unscaled ground motion records
    • Authors: Fatemeh Jalayer; Hossein Ebrahimian, Andrea Miano, Gaetano Manfredi, Halil Sezen
      Abstract: It is desirable that nonlinear dynamic analyses for structural fragility assessment are performed using unscaled ground motions. The widespread use of a simple dynamic analysis procedure known as Cloud Analysis, which uses unscaled records and linear regression, has been impeded by its alleged inaccuracies. This paper investigates fragility assessment based on Cloud Analysis by adopting, as the performance variable, a scalar demand to capacity ratio that is equal to unity at the onset of limit state. It is shown that the Cloud Analysis, performed based on a careful choice of records, leads to reasonable and efficient fragility estimates. There are 2 main rules to keep in mind for record selection: to make sure that a good portion of the records leads to a demand to capacity ratio greater than unity and that the dispersion in records' seismic intensity is considerable. An inevitable consequence of implementing these rules is that one often needs to deal with the so-called collapse cases. To formally consider the collapse cases, a 5-parameter fragility model is proposed that mixes the simple regression in the logarithmic scale with logistic regression. The joint distribution of fragility parameters can be obtained by adopting a Markov Chain Monte Carlo simulation scheme leading directly to the fragility and its confidence intervals. The resulting fragility curves compare reasonably with those obtained from the Incremental Dynamic Analysis and Multiple Stripe Analysis with (variable) conditional spectrum–compatible suites of records at different intensity levels for 3 older reinforced concrete frames with shear-, shear-flexure-, and flexure-dominant behavior.
      PubDate: 2017-06-26T22:53:00.464982-05:
      DOI: 10.1002/eqe.2922
       
  • Cyclic tests of steel plate shear walls using box-shape vertical boundary
           elements with or without infill concrete
    • Authors: Chao-Hsien Li; Keh-Chyuan Tsai, Hsuan-Yu Huang, Ching-Yi Tsai
      Abstract: The steel plate shear wall (SPSW) is an effective lateral force resisting system in which unstiffened steel infill plates are connected to the horizontal and vertical boundary elements (VBEs) on all sides of the plates. The boundary elements must be designed to resist the tension field force of the infill panels. When the VBEs are made from a steel box section, the flange of each box VBE connected with the infill panels can be pulled out-of-plane by significant panel forces, called pull-out action. This study investigates capacity design methods for box VBEs in SPSWs. Simplified fixed beam and portal frame models aim to estimate the pull-out responses of the flange of the box sections with and without infill concrete, respectively. In this study, cyclic tests of three full-scale two-story SPSWs using box VBEs with or without the infill concrete are conducted. Inelastic pushover analyses of the finite element models are conducted. The tests and analytical results confirm that the proposed design methods, which aimed to prevent the full yield of the flange under the pull-out action, are applicable. Furthermore, the test and analytical results suggest that the initial yielding of the flange of box VBEs under the collective effects of the pull-out action on the flange, the gravity load, and the sway action on the SPSW represents a local yielding. A strict prohibition of the initial yielding on the flange under the aforementioned collective effects is not recommended for pursuing a cost-effective design. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-06-22T00:55:29.186302-05:
      DOI: 10.1002/eqe.2917
       
  • Experimental investigation on reparability of an infilled rocking wall
           frame structure
    • Authors: Shoujun Wu; Peng Pan, Xin Nie, Haishen Wang, Shaodong Shen
      Abstract: Improving seismic performance is one of the critical objectives in earthquake engineering. With the development of economy and society, reparability and fast resilience of a structure are becoming increasingly important. Reinforced concrete (RC) frame structure is prone to soft story mechanism. As a result, deformation and damage are so concentrated that reparability is severely hampered. Rocking wall provides an available approach for deformation control in RC frame by introducing a continuous component along the height. Previous researches mostly focus on seismic responses of rocking wall frame structures, while damage mode and reparability have not been investigated in detail. In this study, a novel infilled rocking wall frame (IRWF) structure is proposed. A half-scaled IRWF model was designed according to Chinese seismic design code. The model was subjected to cyclic pushover testing up to structure drift ratio of 1/50 (amplitude 1/50), and its reparability was evaluated thereafter. Retrofit was implemented by wrapping steel plates and installing friction dampers. The retrofitted model was further loaded up to amplitude 1/30. The IRWF model showed excellent reparability and satisfactory seismic performance on deformation control, damage mode, hysteresis behavior, and beam-to-column joint rotation. After retrofitting, capacity of the model was improved by 11% with limited crack distribution. The model did not degrade until amplitude 1/30, due to shear failure in frame beams. The retrofit procedure was proved effective, and reparability of the IRWF model was demonstrated. Seismic resilience tends to be achieved in the proposed system.
      PubDate: 2017-06-20T23:56:31.070408-05:
      DOI: 10.1002/eqe.2930
       
  • Generalised formulation of composite filters and their application to
           earthquake engineering test systems
    • Authors: David Paul Stoten
      Abstract: This paper addresses the problem of generating unmeasured kinetic data—and/or providing improvements in existing data—for the enhancement of performance characteristics of earthquake engineering test systems, such as shaking tables, reaction walls and other custom-made test rigs. The approach relies upon the use of composite filters (CF), a method of data fusion that was originally conceived via transfer function formulation. The current work generalises the CF concept and extends its formulation into the state-space domain, thereby providing a wider basis for application to test systems and their controllers, including those of a multivariable (coupled, multi-axis) nature.Comparative simulation studies of shaking table control are presented that demonstrate the design techniques for state-space CF and also their effectiveness for signal synthesis, noise suppression and performance improvement. Specific examples include the use of CF for displacement demand signal generation, velocity feedback generation and acceleration control. In each case, the essential principles behind CF—output signals with zero bias and zero drift—are consistently upheld. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-06-20T03:07:10.206161-05:
      DOI: 10.1002/eqe.2921
       
  • Sensitivity analysis of the seismic demands of RC moment resisting frames
           to different aspects of ground motions
    • Authors: Jalal Kiani; Shahram Pezeshk
      Abstract: A weight vector representing the relative importance of various characteristics of ground motions (GMs) and a conditioning intensity measure (IM) are required to be able to use the generalized conditional IM framework for the purpose of GM selection. An inappropriate weight vector may result in the biased distributions of some important characteristics of GMs and, consequently, the bias in the structural responses. This article aims to provide the analyst with the understanding of which properties of GMs are important in capturing the accurate structural responses, to specifically assign a suitable weight to them and to select an appropriate conditioning IM as well. To this end, 4 reinforced concrete buildings, located at the site in which the seismic hazard is dominated by shallow crustal earthquakes, are considered. The findings reveal that the appropriate weight vectors depend on the characteristics of the employed structural systems. In addition, the role played by each IM in capturing the true structural responses changes over different earthquake intensity levels implying that different weight vectors are required over different earthquake levels. Furthermore, this study shows that, even in case of shorter-duration GMs from shallow events, GM duration should be incorporated in GM selection as it has effects on the peak-based structural responses in the earthquake levels beyond the level of 2%-in-50-years. Specifically, the findings reveal that in case of shallow events, unlike large magnitude earthquakes, the shorter the duration of GM the more rapid release of energy and, consequently, the larger the peak-based structural responses.
      PubDate: 2017-06-19T00:35:36.662028-05:
      DOI: 10.1002/eqe.2928
       
  • Extreme behavior in a triple friction pendulum isolated frame
    • Authors: Tracy C. Becker; Yu Bao, Stephen A. Mahin
      Abstract: While isolation can provide significantly enhanced performance compared to fixed-base counter parts in design level or even maximum considered level earthquakes, there is still uncertainty over the performance of isolation systems in extreme events. Researchers have looked at component level stability of rubber bearings and on the effect of moat impact on behavior of structures isolated on general bilinear isolators. However, testing of triple friction pendulum (TFP) sliding bearings has not been done dynamically or incorporated into a building system. Here, one-third scale laboratory tests were conducted to on a 2-story 2-bay TFP-isolated structure. Input motions were increasingly scaled until failure occurred at the isolation level. As the superstructure was designed with a yield force equivalent to the force of the bearing just at their ultimate displacement capacity, there was minimal yielding. A numerical model is presented to simulate the isolated building up to and including bearing failure. Forces transferred to the superstructure in extreme motions are examined using both experimental and numerical data. Additionally, the effect of the hardening stage of the TFP bearing is evaluated using the numerical model, finding slight benefits.
      PubDate: 2017-06-15T02:11:57.664811-05:
      DOI: 10.1002/eqe.2924
       
  • Theory and implementation of switch-based hybrid simulation technology for
           earthquake engineering applications
    • Authors: T.Y. Yang; Dorian P. Tung, Yuanjie Li, Jian Yuan Lin, Kang Li, Wei Guo
      Abstract: Hybrid simulation (HS) is a novel technique to combine analytical and experimental sub-assemblies to examine the dynamic responses of a structure during an earthquake shaking. Traditionally, HS uses displacement-based control where the finite element program calculates trial displacements and applies them to both the analytical and experimental sub-assemblies. Displacement-based HS (DHS) has been proven to work well for most structural sub-assemblies. However, for specimens with high stiffness, traditional DHS does not work because it is difficult to precisely control hydraulic actuators in small displacement. A small control error in displacement will result in large force response fluctuations for stiff specimens. This paper resolves this challenge by proposing a force-based HS (FHS) algorithm that directly calculates trial forces instead of trial displacements. The proposed FHS is finite element based and applicable to both linear and nonlinear systems. For specimens with drastic changes in stiffness, such as yielding, a switch-based HS (SHS) algorithm is proposed. A stiffness-based switching criterion between the DHS and FHS algorithms is presented in this paper. All the developed algorithms are applied to a simple one-story one-bay concentrically braced moment frame. The result shows that SHS outperforms DHS and FHS. SHS is then utilized to validate the seismic performance of an innovative earthquake resilient fused structure. The result shows that SHS works in switching between the DHS and FHS modes for a highly nonlinear and highly indeterminate structural system. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-06-15T02:00:54.568465-05:
      DOI: 10.1002/eqe.2920
       
  • Performance-based grouping methods of bridge classes for regional seismic
           risk assessment: Application of ANOVA, ANCOVA, and non-parametric
           approaches
    • Authors: Sujith Mangalathu; Jong-Su Jeon, Jamie E. Padgett, Reginald DesRoches
      Abstract: One of the key tasks to enable a regional risk assessment is to group structures with similar seismic performances and generate fragility curves representative of the grouped structures. The grouping has been traditionally performed based primarily on engineering judgment and prior experience. This paper (i) presents an overview of various statistical techniques such as analysis of variance, analysis of covariance, and Kruskal–Wallis test for grouping the bridges of similar performance; (ii) compares the groupings that emerge from the various grouping techniques; and (iii) identifies the method that has more statistical power in creating bridge sub-classes of distinct structural performance. The grouping is achieved by comparing the structural responses of bridge classes obtained from the non-linear time history analysis of bridges. The relative merits of these grouping techniques are discussed with the case study of box-girder bridges in California. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-06-13T01:52:47.872582-05:
      DOI: 10.1002/eqe.2919
       
  • Analysis of RC slab–beam–column sub-assemblages subjected to
           bidirectional lateral cyclic loading using a new 3D macroelement
    • Authors: Suhee Kim; Fumio Kusuhara, Hitoshi Shiohara
      Abstract: An existing two-dimensional macroelement for reinforced concrete beam–column joints is extended to a three-dimensional macroelement. The three-dimensional macroelement for beam–column joints consists of six rigid interface plates and uniaxial springs for concrete, steel, and bond–slip, which model the inside of a beam–column joint. The mechanical models for the materials and the stiffness equation for the springs are also presented. To validate the model, we used test results from three slab–beam–column sub-assemblages subjected to bi-lateral cyclic load. It is revealed that the new joint model is capable of capturing the strength of beam–column joints and the bidirectional interaction in joint shear response, including the concentration of damage in the beam–column joint, the pinching nature in hysteretic behavior, the stiffness degradation, and strength deterioration resulting from cyclic and bidirectional loading. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-23T00:26:14.376923-05:
      DOI: 10.1002/eqe.2916
       
  • Dynamics of rocking podium structures
    • Authors: J.A. Bachmann; M.F. Vassiliou, B. Stojadinović
      Abstract: A rocking podium structure is a class of structures consisting of a superstructure placed on top of a rigid slab supported by free-standing columns. The free-standing columns respond to sufficiently strong ground motion excitation by uplifting and rocking. Uplift works as a mechanical fuse that limits the forces transmitted to the superstructure, while rocking enables large lateral displacements. Such ‘soft-story’ system runs counter to the modern seismic design philosophy but has been used to construct several hundred buildings in countries of the former USSR following Polyakov's rule-of-thumb guidelines: (i) that the superstructure behave as a rigid body and (ii) that the maximum lateral displacement of the rocking podium frame be estimated using elastic earthquake displacement response spectra. The objectives of this paper are to present a dynamic model for analysis of the in-plane seismic response of rocking podium structures and to investigate if Polyakov's rule-of-thumb guidelines are adequate for the design of such structures. Examination of the rocking podium structure response to analytical pulse and recorded ground motion excitations shows that the rocking podium structures are stable and that Polyakov's rule-of-thumb guidelines produce generally conservative designs. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-23T00:25:58.493838-05:
      DOI: 10.1002/eqe.2915
       
  • Conceptual design and full-scale experimentation of cladding panel
           connection systems of precast buildings
    • Authors: Giandomenico Toniolo; Bruno Dal Lago
      Abstract: Despite the long series of European research projects that has led to the setting of fully reliable seismic design criteria for precast structures, recent earthquakes have shown that a weak point still exists in the proportioning of the connection systems of cladding wall panels. Following this finding, this paper outlines an organic setting of the design problem of precast concrete structures including cladding–structure interaction and describes three possible solutions, namely, the isostatic, integrated, and dissipative systems. The related fastening arrangements, with the use of existing and innovative connection devices, are also described. This paper comments on the results of the pseudo-dynamic and cyclic tests performed at ELSA Laboratory of the European Joint Research Centre of Ispra (Italy) on a full-scale prototype of precast structure. The conception and the experimental performance of the structure with nine different configurations of either vertical or horizontal wall panel claddings are presented. The analysis of the results highlights the effectiveness of the different solutions in a comparative way. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-17T02:16:59.744861-05:
      DOI: 10.1002/eqe.2918
       
  • Experimental study on a new type of earthquake resilient shear wall
    • Authors: Qizhou Liu; Huanjun Jiang
      Abstract: Reinforced concrete (RC) shear walls have been extensively used as lateral load resisting structural members in tall buildings. However, in the past, strong earthquake events RC structural walls in some buildings suffered severe damage, which concentrated at the bottom and was very difficult to be repaired. The installation of the replaceable corner components (RCCs) at the bottom of the structural wall is a new method to form an earthquake resilient structural wall whose function can be quickly restored by replacing the RCCs after the strong earthquake because of the damage concentrating on RCCs. In this study, a new kind of replaceable energy-dissipation component installed at the bottom corner of RC structural walls was proposed. To study the seismic performance of the new structural wall with RCCs, the cyclic loading tests on three new structural wall specimens and one conventional RC structural wall specimen were conducted. One of the new structural wall specimens experienced replacement and reloading process to verify the feasibility of replacement. The results show that the structural behavior of all specimens was flexure dominating. The damage in the new shear specimens mainly concentrated on RCCs. The replacement of RCCs can be implemented conveniently after the residual deformation occurred in the structure. Compared with the conventional structural wall specimen, the seismic performance of new structural wall specimens was improved significantly. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-17T02:16:30.233688-05:
      DOI: 10.1002/eqe.2914
       
  • Predominant period and equivalent viscous damping ratio identification for
           a full-scale building shake table test
    • Authors: Michelle C. Chen; Rodrigo Astroza, José I. Restrepo, Joel P. Conte, Tara Hutchinson, Yehuda Bock
      Abstract: The predominant period and corresponding equivalent viscous damping ratio, also known in various loading codes as effective period and effective damping coefficient, are two important parameters employed in the seismic design of base-isolated and conventional building structures. Accurate determination of these two parameters can reduce the uncertainty in the computation of lateral displacement demands and interstory drifts for a given seismic design spectrum. This paper estimates these two parameters from data sets recorded from a full-scale five-story reinforced concrete building subjected to seismic base excitations of various intensities in base-isolated and fixed-base configurations on the outdoor shake table at the University of California, San Diego. The scope of this paper includes all test motions in which the yielding of the reinforcement has not occurred and the response can still be considered ‘elastic’. The data sets are used with three system identification methods to determine the predominant period of response for each of the test configurations. One of the methods also determines the equivalent viscous damping ratio corresponding to the predominant period. It was found that the predominant period of the fixed-base building lengthened from 0.52 to 1.30 s. This corresponded to a significant reduction in effective system stiffness to about 16% of the original stiffness. The paper then establishes a correlation between predominant period and peak ground velocity. Finally, the predominant periods and equivalent viscous damping ratios recommended by the ASCE 7-10 loading standard are compared with those determined from the test building. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-17T02:10:41.002973-05:
      DOI: 10.1002/eqe.2913
       
  • Low-seismic damage strategies for infilled RC frames: shake-table tests
    • Authors: H. Zhang; J.S. Kuang, Terry Y.P. Yuen
      Abstract: Unreinforced masonry (URM) infill panels are widely used as partitions in RC frames and typically considered as non-structural elements in the design process. However, observations from recent major earthquakes have shown that under seismic excitation, the structural interaction between columns and infill walls can significantly alter the structural behaviour, thus causing catastrophic consequences. The purpose of this research was to propose and test an innovative low seismic damage detailing method, which isolates the infill panel from bounding columns with finite width vertical gaps during the infill panel construction phase and deploys steel wire connections in mortar layers anchored to columns. Taking into account the similitude requirements, a total of six one-third scale, single-storey single-bay RC frames with different infill configurations and flexible connection details were carefully designed and tested on a shake-table. Three real earthquake records were selected and scaled to ascending intensity levels and used as input signals. A series of thorough investigations including dynamic characteristics, hysteretic behaviour, failure mechanisms, out-of-plane vulnerabilities and the effect of different gap filling materials and load transfer mechanisms were rigorously studied. The experimental results indicate that the undesirable interaction between infill panels and bounding frame is significantly reduced using the proposed low seismic damage detailing concept. Direct shear failure of columns at an early stage is prevented, and structural redundancy at high levels of excitation can be provided. In general, the structural stability and integrity, and displacement ductility of infilled RC frames can remarkably be improved. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-15T00:45:59.178134-05:
      DOI: 10.1002/eqe.2911
       
  • Damage mechanics applied to performance-based design of reinforced
           concrete columns
    • Authors: Luis Ignacio Cardona; Patrick Paultre, Jacky Mazars
      Abstract: Performance-based design methodology is based on reaching performance objectives that are associated to certain damage conditions. These performance objectives are related to the seismic hazard and to the performance levels. In actual application, reliable tools are required for capturing the evolution of the damage condition as well as for measuring and locating it. Moreover, it is essential to accurately establish the relationship between the damage and the performance levels. This paper shows the application of damage mechanics to performance-based design. A layered damage mechanics-based finite element program is presented with a discussion on modeling for prediction of the response of normal-strength and high-strength concrete columns subjected to cyclic flexural loading and various axial load levels. The damage indices derived from these analyses were used to elaborate several damage charts expressed as a function of drift and displacement ductility. This makes it possible to establish a relationship between the damage state and the performance levels. Results have demonstrated the ability of the damage mechanics modeling to accurately predict the behavior of the specimens tested.
      PubDate: 2017-05-15T00:45:47.048095-05:
      DOI: 10.1002/eqe.2912
       
  • Force-displacement model for solid confined masonry walls with
           shear-dominated failure mode
    • Authors: Mohammad Yekrangnia; Ali Bakhshi, Mohammad Ali Ghannad
      Abstract: This paper addresses the behavior of confined masonry walls with dominating shear failure mode in walls. For this purpose, failure modes of these walls are classified in details. For each failure mode, complete set of analytical-based relations for deriving parameters related to backbone curves is introduced. Calibrated finite element analyses are utilized as a benchmark for verification of some of the assumptions. The results of the proposed relations are compared with those of several Iranian and non-Iranian experimental data. Sensitivity analysis is performed in order to understand the effects of important behavioral characteristics of these walls. The results of this study indicate that the proposed relations can accurately simulate behavior of confined masonry walls with dominating shear failure mode regardless of the failure mode in the ties. Moreover, it is concluded that the detailing limitations given in the Iranian Seismic Code are rationally compatible with the behavioral characteristics of confided masonry walls. The results of this study in terms of backbone curves can be utilized as the complementary part to this code. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-15T00:40:45.002455-05:
      DOI: 10.1002/eqe.2902
       
  • Amplitude dependence of equivalent modal parameters in monitored buildings
           during earthquake swarms
    • Authors: Rosario Ceravolo; Emiliano Matta, Antonino Quattrone, Luca Zanotti Fragonara
      Abstract: This paper investigates the dynamic response of three sample buildings belonging to the Seismic Observatory for Structures, the Italian network for the permanent seismic monitoring of strategic structures, managed by the Italian Department of Civil Protection. The case studies cover different building types that could loosely represent the Italian building stock, with a special emphasis on cultural heritage and masonry structures.Observed under a low-intensity seismic swarm comprising about 30 aftershocks after a main event, the three buildings are analysed through an input–output, model-driven linear dynamic identification procedure, depicting the relation between the shaking level at the site and the variation of the equivalent structural modal parameters, while keeping into account the effects of soil–structure interaction. Finite element models will be used to investigate one of the case studies and to compare the law of variation of the structural modal parameters with respect to simplified models proposed by technical standards. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-08T23:00:46.668354-05:
      DOI: 10.1002/eqe.2910
       
  • Boundary frame contribution in coupled and uncoupled steel plate shear
           walls
    • Authors: Meng Wang; Daniel J. Borello, Larry A. Fahnestock
      Abstract: The steel plate shear wall (SPSW) system is a robust option for earthquake resistance due to the strength, stiffness, ductility and energy dissipation that it provides. Although thin infill plates are efficient for resisting lateral loads, boundary frames that are proportioned based on capacity design requirements add significant structural weight that appears to be one of the factors limiting the use of the system in practice. An alternate configuration, the SPSW with coupling (SPSW-WC), was explored recently as an option for increasing architectural flexibility while also improving overall system economy and seismic performance. The SPSW-WC, which extensively employs flexural boundary frame contribution, has shown promise in analytical, numerical and experimental studies, but recent research on uncoupled SPSWs suggests that boundary frame contribution should not be considered for carrying seismic design shear. As a result, in the present study, boundary frame contribution in SPSWs was explored with detailed three-dimensional finite element models, which were validated against large-scale SPSW-WC tests. Six-story systems were considered, and the study matrix included single and double uncoupled SPSWs along with coupled SPSWs that had various degrees of coupling. Variations in design methodology were also explored. The modeling framework was employed to conduct static monotonic and cyclic pushover analyses and dynamic response history analysis. These analyses demonstrate the beneficial effect of coupling in SPSWs and illustrate the need to consider boundary frame contribution in design of coupled SPSWs. In addition, sharing design shear between the infill plate and the boundary frame is more generally shown to not be detrimental if this sharing is done in the design stage based on elastic analysis and the resulting boundary frame provides adequate secondary strength and stiffness following infill plate yielding. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-04T00:20:52.229197-05:
      DOI: 10.1002/eqe.2908
       
  • Rocking damage-free steel column base with friction devices: design
           procedure and numerical evaluation
    • Authors: Fabio Freddi; Christoforos A. Dimopoulos, Theodore L. Karavasilis
      Abstract: Earthquake-resilient steel frames, such as self-centering frames or frames with passive energy dissipation devices, have been extensively studied during the past decade, but little attention has been paid to their column bases. The paper presents a rocking damage-free steel column base, which uses post-tensioned high-strength steel bars to control rocking behavior and friction devices to dissipate seismic energy. Contrary to conventional steel column bases, the rocking column base exhibits monotonic and cyclic moment–rotation behaviors that are easily described using simple analytical equations. Analytical equations are provided for different cases including structural limit states that involve yielding or loss of post-tensioning in the post-tensioned bars. A step-by-step design procedure is presented, which ensures damage-free behavior, self-centering capability, and adequate energy dissipation capacity for a predefined target rotation. A 3D nonlinear finite element (FE) model of the column base is developed in abaqus. The results of the FE simulations validate the accuracy of the moment–rotation analytical equations and demonstrate the efficiency of the design procedure. Moreover, a simplified model for the column base is developed in OpenSees. Comparisons among the OpenSees and abaqus models demonstrate the efficiency of the former and its adequacy to be used in nonlinear dynamic analysis. A prototype steel building is designed as a self-centering moment-resisting frame with conventional or rocking column bases. Nonlinear dynamic analyses show that the rocking column base fully protects the first story columns from yielding and eliminates the first story residual drift without any detrimental effect on peak interstory drifts. The study focuses on the 2D rocking motion and, thus, ignores 3D rocking effects such as biaxial bending deformations in the friction devices. The FE models, the analytical equations, and the design procedure will be updated and validated to cover 3D rocking motion effects after forthcoming experimental tests on the column base. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-05-02T10:32:11.181643-05:
      DOI: 10.1002/eqe.2904
       
  • Reliability-based control algorithms for nonlinear hysteretic systems
           based on enhanced stochastic averaging of energy envelope
    • Authors: Omar El-Khoury; Abdollah Shafieezadeh
      Abstract: Current reliability-based control techniques have been successfully applied to linear systems; however, incorporation of stochastic nonlinear behavior of systems in such control designs remains a challenge. This paper presents two reliability-based control algorithms that minimize failure probabilities of nonlinear hysteretic systems subjected to stochastic excitations. The proposed methods include constrained reliability-based control (CRC) and unconstrained reliability-based control (URC) algorithms. Accurate probabilistic estimates of nonlinear system responses to stochastic excitations are derived analytically using enhanced stochastic averaging of energy envelope proposed previously by the authors. Convolving these demand estimates with capacity models yields the reliability of nonlinear systems in the control design process. The CRC design employs the first-level and second-level optimizations sequentially where the first-level optimization solves the Hamilton–Jacobi–Bellman equation and the second-level optimization searches for optimal objective function parameters to minimize the probability of failure. In the URC design, a single optimization minimizes the probability of failure by directly searching for the optimal control gain. Application of the proposed control algorithms to a building on nonlinear foundation has shown noticeable improvements in system performance under various stochastic excitations. The URC design appears to be the most optimal method as it reduced the probability of slight damage to 8.7%, compared with 11.6% and 19.2% for the case of CRC and a stochastic linear quadratic regulator, respectively. Under the Kobe ground motion, the normalized peak drift displacement with respect to stochastic linear quadratic regulator is reduced to 0.78 and 0.81 for the URC and CRC cases, respectively, at comparable control force levels. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-21T00:13:10.85735-05:0
      DOI: 10.1002/eqe.2909
       
  • Empirical seismic fragility for the precast RC industrial buildings
           damaged by the 2012 Emilia (Italy) earthquakes
    • Authors: Nicola Buratti; Fabio Minghini, Elena Ongaretto, Marco Savoia, Nerio Tullini
      Abstract: The paper analyses the seismic fragility of precast reinforced concrete buildings using observational damage data gathered after the 2012 Emilia earthquakes that struck Northern Italy. The damage level in 1890 buildings was collected, classified and examined. Damage matrices were then evaluated, and finally, empirical fragility curves were fitted using Bayesian regression. Building damage was classified using a six-level scale derived from EMS-98. The completeness of the database and the spatial distribution of the buildings investigated were analysed using cadastral data as a reference. The intensity of the ground motion was quantified by the maximum horizontal peak ground acceleration, which was obtained from ShakeMaps. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-20T22:49:07.535394-05:
      DOI: 10.1002/eqe.2906
       
  • Earthquake-induced loss assessment of steel frame buildings with special
           moment frames designed in highly seismic regions
    • Authors: Seong-Hoon Hwang; Dimitrios G. Lignos
      Abstract: This paper discusses an analytical study that quantifies the expected earthquake-induced losses in typical office steel frame buildings designed with perimeter special moment frames in highly seismic regions. It is shown that for seismic events associated with low probabilities of occurrence, losses due to demolition and collapse may be significantly overestimated when the expected loss computations are based on analytical models that ignore the composite beam effects and the interior gravity framing system of a steel frame building. For frequently occurring seismic events building losses are dominated by non-structural content repairs. In this case, the choice of the analytical model representation of the steel frame building becomes less important. Losses due to demolition and collapse in steel frame buildings with special moment frames designed with strong-column/weak-beam ratio larger than 2.0 are reduced by a factor of two compared with those in the same frames designed with a strong-column/weak-beam ratio larger than 1.0 as recommended in ANSI/AISC-341-10. The expected annual losses (EALs) of steel frame buildings with SMFs vary from 0.38% to 0.74% over the building life expectancy. The EALs are dominated by repairs of acceleration-sensitive non-structural content followed by repairs of drift-sensitive non-structural components. It is found that the effect of strong-column/weak-beam ratio on EALs is negligible. This is not the case when the present value of life-cycle costs is selected as a loss-metric. It is advisable to employ a combination of loss-metrics to assess the earthquake-induced losses in steel frame buildings with special moment frames depending on the seismic performance level of interest. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-17T23:45:38.231936-05:
      DOI: 10.1002/eqe.2898
       
  • Shake table testing on restoring capability of double concave friction
           pendulum seismic isolation systems
    • Authors: Felice Carlo Ponzo; Antonio Di Cesare, Gianmarco Leccese, Domenico Nigro
      Abstract: After an earthquake, non-negligible residual displacements may affect the serviceability of a base isolated structure, if the isolation system does not possess a good restoring capability. The permanent offset does not affect the performance unless the design is problematic for utilities, also considering possible concerns related to the maintenance of the devices.Starting from experimental and analytical results of previous studies, the restoring capability of Double Concave Friction Pendulum bearings is investigated in this paper. A simplified design suggestion for the estimation of maximum expected residual displacements for currently used friction pendulum systems is then validated. The study is based on controlled-displacement and seismic input experiments, both performed under unidirectional motion. Several shaking table tests have been carried out on a three-dimensional isolated specimen structure. The same sequence of seismic inputs was applied considering three different conditions of sliding surfaces corresponding to low, medium and high friction. The accumulation of residual displacements is also investigated by means of nonlinear dynamic analysis. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-11T22:16:28.060146-05:
      DOI: 10.1002/eqe.2907
       
  • Accidental eccentricity in symmetric buildings due to wave passage effects
           arising from near-fault pulse-like ground motions
    • Authors: Yenan Cao; George P. Mavroeidis, Kristel C. Meza-Fajardo, Apostolos S. Papageorgiou
      Abstract: This article investigates the characteristics of the accidental eccentricity in symmetric buildings due to torsional response arising from wave passage effects in the near-fault region. The soil–foundation–structure system is modeled as a symmetric cylinder placed on a rigid circular foundation supported on an elastic halfspace and subjected to obliquely incident plane SH waves simulating the action of near-fault pulse-like ground motions. The translational response is computed assuming that the superstructure behaves as a shear beam under the action of translational and rocking base excitations, whereas the torsional response is calculated using the mathematical formulation proposed in a previous study. A broad range of properties of the soil–foundation–structure system and ground motion input are considered in the analysis, thus facilitating a detailed parametric investigation of the structural response. It is demonstrated that the normalized accidental eccentricity is most sensitive to the pulse period (TP) of the near-fault ground motions and to the uncoupled torsional-to-translational fundamental frequency ratio (Ω) of the structure. Furthermore, the normalized accidental eccentricities due to simplified pulse-like and broadband ground motions in the near-fault region are computed and compared against each other. The results show that the normalized accidental eccentricity due to the broadband ground motion is well approximated by the simplified pulse for longer period buildings, while it is underestimated for shorter period buildings. For symmetric buildings with values of Ω commonly used in design practice, the normalized accidental eccentricity due to wave passage effects is less than the typical code-prescribed value of 5%, except for buildings with very large foundation radius. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-10T22:06:08.646974-05:
      DOI: 10.1002/eqe.2901
       
  • Investigation of the dynamic behaviour of a storage tank with different
           foundation types focusing on the soil-foundation-structure interactions
           using centrifuge model tests
    • Authors: Heon-Joon Park; Jeong-Gon Ha, Sun-Yong Kwon, Moon-Gyo Lee, Dong-Soo Kim
      Abstract: This paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage-tank structure. It was used in the present study to investigate the soil-foundation-structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-10T22:05:56.371557-05:
      DOI: 10.1002/eqe.2905
       
  • Tracking modal parameters from building seismic response data using
           recursive subspace identification algorithm
    • Authors: Chin-Hsiung Loh; Jun-Da Chen
      Abstract: Tracking modal parameters and estimating the current structural state of a building from seismic response measurements, particularly during strong earthquake excitations, can provide useful information for building safety assessment and the adaptive control of a structure. Therefore, online or recursive identification techniques need to be developed and implemented for building seismic response monitoring. This paper develops and examines different methods to track modal parameters from building seismic response data. The methods include recursive data-driven subspace identification (RSI-DATA) using Givens rotation algorithm, and RSI-DATA using Bona fide algorithm. The question on how well the results of RSI-DATA reflect the real condition is investigated and verified with a bilinear SDOF simulation study. Time-varying modal parameters of a four-story reinforced concrete school building are identified based on a series of earthquake excitations, including several seismic events, large and small. Discussions on the different methods' ability to track the time-varying modal parameters are presented. The variation of the identified building modal frequencies and damping ratios from a series of event-by-event seismic responses, particularly before and after retrofitting of the building is also discussed. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-06T18:51:47.672077-05:
      DOI: 10.1002/eqe.2900
       
  • The three-dimensional behavior of inverted pendulum cylindrical structures
           during earthquakes
    • Authors: Michalis F. Vassiliou; Stefan Burger, Marius Egger, Jonas A. Bachmann, Marco Broccardo, Bozidar Stojadinovic
      Abstract: In order to use rocking as a seismic response modification strategy along both directions of seismic excitation, a three-dimensional (3D) rocking model should be developed. Since stepping or rolling rocking structural members out of their initial position is not a desirable performance, a rocking design should not involve these modes of motion. To this end, a model that takes the aforementioned constraint into account needs to be developed. This paper examines the 3D motion of a bounded rigid cylinder that is allowed to uplift and sustain rocking and wobbling (unsteady rolling) motion without sliding or rolling out of its initial position (i.e., a 3D inverted pendulum). Thus, the cylinder is constrained to zero residual displacement at the end of its 3D motion. This 3D dynamic model of the rocking rigid cylinder has two DOFs (three when damping is included), making it the simplest 3D extension of Housner's classical two-dimensional (2D) rocking model. The development of models with and without damping is presented first. They are simple enough to perform extensive parametric analyses. Modes of motion of the cylinder are identified and presented. Then, 3D rocking and wobbling earthquake response spectra are constructed and compared with the classical 2D rocking earthquake response spectra. The 3D bounded rocking earthquake response spectra for the ground motions considered seem to have a very simple linear form. Finally, it is shown that the use of a 2D rocking model may lead to unacceptably unconservative estimates of the 3D rocking and wobbling seismic response. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-06T18:51:29.003823-05:
      DOI: 10.1002/eqe.2903
       
  • Evidence of significant forward rupture directivity aggravated by soil
           response in an Mw6 earthquake and the effects on monuments
    • Authors: E. Garini; G. Gazetas, I. Anastasopoulos
      Abstract: While strong directivity effects have been mostly recognized in Mw > 6.5 earthquakes, the paper investigates the case of a strong such effect in a relatively small-magnitude event on 3 February 2014 in the island of Cephalonia, Greece. The second of two events (both of Mw ≈ 6) produced a pernicious accelerogram in the region's main town, Lixouri. The paper provides evidence from geology, interferometry, and seismology to convince that the motion was the result of constructive interference in front of the direction of rupture of the obliquely-strike-slip fault. The nature of the record is explored to demonstrate that its frequency content, its high velocity pulse, and its strong fault-normal (FN) favorable polarity are associated with directivity. Moreover, the broad spectral acceleration peak (of 1.7 g) of the FN motion, centered at a period (T ≈ 1.4 s) which almost coincides with the period of the velocity pulse, is shown to have also been affected by soil amplification, in quantitative agreement with Bray et al. (2009). Such a directivity-and-soil-affected motion explains much of the profound damage to monuments, slopes, and harbor quaywalls. In particular, toppling (as well as excessive rotation and sliding) of nearly-all the tombstones in Lixouri cemetery are shown to correlate well with characteristics of the FN component of motion. By contrast, the excellent performance of the building stock — despite the destructive shaking that prevailed — is persuasively attributed to conservatively-robust construction practices of the past and the high base shear coefficient of the strict latest (2000) seismic code. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-04-03T02:11:08.581802-05:
      DOI: 10.1002/eqe.2895
       
  • Replaceable links with direct brace attachments for eccentrically braced
           frames
    • Authors: Mehmet Bakır Bozkurt; Cem Topkaya
      Abstract: This paper reports findings of an experimental study conducted on replaceable links for steel eccentrically braced frames (EBFs). A replaceable link detail which is based on splicing the directly connected braces and the beam outside the link is proposed. This detail eliminates the need to use hydraulic jacks and flame cutting operations for replacement purposes. Performance of this proposed replaceable link was studied by conducting eight nearly full-scale EBF tests under quasi-static cyclic loading. The link length ratio, stiffening of the link, loading protocol, connection type, bolt pretension, gap size of splice connections, and demand-to-capacity ratios of members were considered as the prime variables. The specimens primarily showed two types of failure modes: link web fracture and fracture of the flange at the link-to-brace connection. No failures were observed at the splice connections indicating that the proposed replaceable link detail provides an excellent response. The inelastic rotation capacity provided by the replaceable links satisfied the requirements of the AISC Seismic Provisions for Structural Steel Buildings (AISC341–10). The overstrength factor of the links exceeded 2.0, which is larger than the value assumed for EBF links by design provisions. The high level of overstrength resulted in brace buckling in one of the specimens demonstrating the importance of overstrength factor used for EBF links. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-03-29T22:20:38.536271-05:
      DOI: 10.1002/eqe.2896
       
  • Aftershock collapse fragility curves for non-ductile RC buildings: a
           scenario-based assessment
    • Authors: Marco Gaetani d'Aragona; Maria Polese, Kenneth J. Elwood, Majid Baradaran Shoraka, Andrea Prota
      Abstract: Recent studies have addressed the computation of fragility curves for mainshock (MS)-damaged buildings. However, aftershock (AS) fragilities are generally conditioned on a range of potential post-MS damage states that are simulated via static or dynamic analyses performed on an intact building. Moreover, there are very few cases where the behavior of non-ductile reinforced concrete buildings is analyzed.This paper presents an evaluation of AS collapse fragility conditioned on various return periods of MSs, allowing for the rapid assessment of post-earthquake safety variations based solely on the intensity of the damaging earthquake event. A refined multi-degree-of-freedom model of a seven-storey non-ductile building, which includes brittle failure simulations and the evaluation of a system level collapse, is adopted. Aftershock fragilities are obtained by performing an incremental dynamic analysis for a number of MS–AS ground motion sequences and a variety of MS intensities.The AS fragilities show that the probability of collapse significantly increases for higher return periods for the MS. However, this result is mainly ascribable to collapses occurred during MSs. When collapse cases that occur during a MS are not considered in the assessment of AS collapse probability, a smaller shift in the fragility curves is observed as the MS intensity increases. This result is justified considering the type of model and collapse modes introduced, which strongly depend on the brittle behavior of columns failing in shear or due to axial loads. The analysis of damage that is due to MSs when varying the return period confirms this observation. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-03-24T06:05:43.909318-05:
      DOI: 10.1002/eqe.2894
       
  • Collapse risk of controlled rocking steel braced frames with different
           post-tensioning and energy dissipation designs
    • Authors: Taylor C. Steele; Lydell D. A. Wiebe
      Abstract: Controlled rocking steel braced frames (CRSBFs) are low-damage self-centring lateral force resisting systems. Previous studies have shown that designing the energy dissipation (ED) and post-tensioning (PT) in CRSBFs using a response modification factor of R=8 can prevent collapse of structures during earthquakes beyond the design level. However, designers have unique control over the hysteretic behaviour of the system, even after the response modification factor is selected. Additionally, recent studies have suggested that CRSBFs could also be designed using R>8 while still satisfying performance limits. This paper examines how the response modification factor and the design of the ED and PT influence the collapse performance of CRSBFs with three and six storeys where collapse occurs because of over-rotation of the base rocking joint. In addition, the influence of using an additional rocking joint above the base to mitigate higher-mode forces is evaluated for a 12-storey frame. A total of 18 different designs are considered for the three buildings using different ED and PT design parameters, including different response modification factors. A suite of 44 ground motions is scaled until at least 50% of the records cause collapse, and fragility curves are generated using the truncated incremental dynamic analysis curves. The results from two different assessment methodologies show that the parameters selected have a marked influence on the collapse performance of a CRSBF. Nevertheless, even CRSBFs designed using R>8 or without supplemental ED can have acceptably low probabilities of collapse, provided that the frame members are designed to remain elastic. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-03-24T06:02:03.225473-05:
      DOI: 10.1002/eqe.2892
       
  • A new smooth hysteretic model for ductile flexural-dominated reinforced
           concrete bridge columns
    • Authors: Ping-Hsiung Wang; Yu-Chen Ou, Kuo-Chun Chang
      Abstract: A new smooth hysteretic model is proposed for ductile, flexural-dominated reinforced concrete bridge columns. Four columns designed per modern seismic codes were tested using monotonically increasing and variable-amplitude cyclic loading protocols and ground motion loading to develop the model. Based on the test results, hysteretic rules for damage accumulation and path dependence of reloading were constructed. For damage accumulation, unloading stiffness degradation is correlated with the maximum displacement and hysteretic energy dissipation, while reloading stiffness degradation is set equal to the unloading stiffness degradation. Pinching severity is related to the residual displacement in the direction opposite to the loading direction. Strength deterioration is correlated with the damage index and does not occur until the damage index reaches a threshold, after which the deterioration is proportional to the increase of the damage index. For path dependence of reloading, reloading paths are classified into primary paths and associate paths. The primary paths are those that start from a residual displacement that is equal to or larger than the previous maximum one. The associate paths are those that do not belong to primary paths and tend to be directed towards certain points. Reloading without load reversal is assumed to be linear. Comparison with the results of pseudo-dynamic tests using three consecutive ground motions showed that the proposed model closely matched the test results. Copyright © 2017 John Wiley & Sons, Ltd.
      PubDate: 2017-02-16T05:15:58.163777-05:
      DOI: 10.1002/eqe.2875
       
  • Issue Information
    • Pages: 2061 - 2062
      Abstract: No abstract is available for this article.
      PubDate: 2017-09-13T00:13:05.840418-05:
      DOI: 10.1002/eqe.2822
       
 
 
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