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  Subjects -> ENGINEERING (Total: 2268 journals)
    - CHEMICAL ENGINEERING (190 journals)
    - CIVIL ENGINEERING (183 journals)
    - ELECTRICAL ENGINEERING (103 journals)
    - ENGINEERING (1201 journals)
    - ENGINEERING MECHANICS AND MATERIALS (380 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (67 journals)
    - MECHANICAL ENGINEERING (89 journals)

CIVIL ENGINEERING (183 journals)                     

Showing 1 - 183 of 183 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: 35)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
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: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
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: 10)
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)
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: 12)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
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: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 265)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
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: 9)
Construction Management and Economics     Hybrid Journal   (Followers: 22)
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: 9)
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: 14)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 9)
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: 5)
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: 12)
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: 4)
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 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: 13)
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: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
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: 40)
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 Civil Engineering Forum     Open Access  
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   (Followers: 1)
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: 7)
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)
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: 10)
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: 13)
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  [1579 journals]
  • Bivariate Gaussian mixture–based equivalent linearization method for
           stochastic seismic analysis of nonlinear structures
    • Authors: Sang-ri Yi; Ziqi Wang, Junho Song
      Abstract: To address challenges in stochastic seismic analysis of nonlinear structures, this paper further develops a recently proposed Gaussian mixture–based equivalent linearization method (GM-ELM). The GM-ELM uses a Gaussian mixture distribution model to approximate the probabilistic distribution of a nonlinear system response. Using properties of the Gaussian mixture model, GM-ELM can decompose the non-Gaussian response of a nonlinear system into multiple Gaussian responses of linear single–degree of freedom oscillators. With the set of the equivalent linear systems identified by GM-ELM, response statistics as crossing rate and first-passage probability can be computed conveniently using theories of linear random vibration analysis. However, the original version of GM-ELM may lead to an inaccurate estimate because of the heuristic parameters of the linear system introduced to supplement insufficient information. To overcome this limitation and define unique equivalent linear systems, this paper proposes a further developed version of GM-ELM, which uses a mixture of bivariate Gaussian densities instead of univariate models. Moreover, to facilitate the use of elastic response spectra for estimating the mean peak responses of a nonlinear structure, a new response spectrum combination rule is proposed for GM-ELM. Two numerical examples of hysteretic structural systems are presented in this paper to illustrate the application of the bivariate GM-ELM to nonlinear stochastic seismic analysis. The analysis results obtained by the bivariate GM-ELM are compared with those obtained by the univariate GM-ELM, the conventional equivalent linearization method, the tail equivalent linearization method, and Monte Carlo simulation. The supporting source code and data are available for download at https://github.com/yisangri/GitHub-bGM-ELM-code.git
      PubDate: 2017-11-07T23:26:01.624865-05:
      DOI: 10.1002/eqe.2985
       
  • Semiactive control of rigid blocks under earthquake excitation
    • Authors: Marica L. Pecorelli; Rosario Ceravolo
      Abstract: This paper investigates the usefulness of a semiactive control to reduce the overturning vulnerability of a rigid block on a rigid plane under earthquake excitation. The proposed feedback law is used to set the stiffness of restraints placed at the 2 lower corners of the block. The performance of the semiactive control is numerically validated by subjecting the block to 100 recorded accelerograms. Specific simulations are performed to study the effect of different anchorage design parameters on the utility of the control. Finally, the robustness of the proposed control is addressed with respect to typical issues of the real-world implementation.
      PubDate: 2017-11-06T01:26:19.509253-05:
      DOI: 10.1002/eqe.2988
       
  • On the descending branch of the pushover curve for multistory buildings
    • Authors: John F. Hall
      Abstract: The paper discusses nonlinear pushover curves for multistory moment-frame buildings. Attention is brought to the steepening effect that elastic unloading has on the slope of the descending branch of the pushover curve, with the possibility of snapback. Displacement control is shown to be effective for the entire range of pushover analysis, including the descending branch. The method is enhanced by controlling the difference in displacement of 2 floors in the vicinity of the collapse mechanism rather than, say, controlling the roof displacement. An automated drift control version is described and tested. Analysis of a 20-story building demonstrates that variable strength of plastic hinges and inclusion of the strength and stiffness of the gravity frames in the model affect the pushover curve significantly, especially the descending branch. The concept of dynamic pushover is described, and results are compared with the static version.
      PubDate: 2017-11-06T01:25:36.089503-05:
      DOI: 10.1002/eqe.2990
       
  • Lifecycle cost optimization of tuned mass dampers for the seismic
           improvement of inelastic structures
    • Authors: Emiliano Matta
      Abstract: The seismic performance of tuned mass dampers (TMDs) on structures undergoing inelastic deformations may largely depend on the ground motion intensity. By estimating the impact of each seismic intensity on the overall cost of future seismic damages, lifecycle cost (LCC) proves a rational metric for evaluating the benefits of TMDs on inelastic structures. However, no incorporation of this metric into an optimization framework is reported yet. This paper presents a methodology for the LCC-optimal design of TMDs on inelastic structures, which minimizes the total seismic LCC of the combined building-TMD system. Its distinctive features are the assumption of a mass-proportional TMD cost model, the adoption of an iterative suboptimization procedure, and the initialization of the TMD frequency and damping ratios according to a conventional linear TMD design technique. The methodology is applied to the seismic improvement of the SAC-LA benchmark buildings, taken as representative of standard steel moment-resisting frame office buildings in LA, California. Results show that, despite their limited performance at the highest intensity levels, LCC-optimal TMDs considerably reduce the total LCC, to an extent that depends on both the building vulnerability and the TMD unit cost. They systematically present large mass ratios (around 10%) and frequency and damping ratios close to their respective linearly designed optima. Simulations reveal the effectiveness of the proposed design methodology and the importance of adopting a nonlinear model to correctly evaluate the cost-effectiveness of TMDs on ordinary structures in highly seismic areas.
      PubDate: 2017-11-02T23:11:14.538684-05:
      DOI: 10.1002/eqe.2987
       
  • Effect of vehicle bridge interaction on seismic response and fragility of
           bridges
    • Authors: Sabarethinam Kameshwar; Jamie E. Padgett
      Abstract: This study focuses on understanding and evaluating the effect of vehicle bridge interaction (VBI) on the response and fragility of bridges subjected to earthquakes. A comprehensive study on the effect of VBI on bridge seismic performance is conducted, providing metamodels for seismic response and fragility estimates for bridges in the presence of various types of vehicles. For this purpose, the performance of multispan simply supported concrete girder bridges with varying design and geometric parameters is assessed with 3 different types of stationary trucks placed atop them. To delineate the effects of VBI and additional truck mass, the trucks are modeled in 2 different ways—with additional masses and suspension springs (ie, with VBI) and using additional masses only (without VBI). The results provide insight on VBI effects, such as the fact that when bridge and vehicle mode shapes are in-phase, the component responses increase and vice versa; additionally, the presence of a heavy axle near a bent increases component responses. Sensitivity analyses are also performed to determine the bridge parameters that significantly alter the component responses in the presence of vehicles. Furthermore, differences in component responses and fragilities highlight that modeling vehicles with additional masses alone is not sufficient to model the effect of truck presence on the seismic response of bridges. Finally, this study concludes that depending on the characteristics of the bridge and the vehicle, presence of a vehicle atop the bridge during an earthquake may be either beneficial or detrimental to bridge performance.
      PubDate: 2017-10-29T21:15:46.92742-05:0
      DOI: 10.1002/eqe.2986
       
  • Predictive model for site specific simulation of ground motions based on
           earthquake scenarios
    • Authors: Christos Vlachos; Konstantinos G. Papakonstantinou, George Deodatis
      Abstract: A predictive stochastic model is developed based on regression relations that inputs a given earthquake scenario description and outputs seismic ground acceleration time histories at a site of interest. A bimodal parametric non-stationary Kanai-Tajimi (K-T) ground motion model lies at the core of the proposed predictive model. The functional forms that describe the temporal evolution of the K-T model parameters can effectively represent strong non-stationarities of the ground motion. Fully non-stationary ground motion time histories can be generated through the powerful Spectral Representation Method. A Californian subset of the available NGA-West2 database is used to develop and calibrate the predictive model. Samples of the model parameters are obtained by fitting the K-T model to the database records, and the resulting marginal distributions of the model parameters are efficiently described by standard probability models. The samples are translated to the standard normal space and linear random-effect regression models are established relating the transformed normal parameters to the commonly used earthquake scenario defining predictors: moment magnitude Mw, closest-to-site distance Rrup, and average shear-wave velocity VS30 at a site of interest. The random-effect terms in the developed regression models can effectively model the correlation among ground motions of the same earthquake event, in parallel to taking into account the location-dependent effects of each site. For validation purposes, simulated acceleration time histories based on the proposed predictive model are compared with recorded ground motions. In addition, the median and median plus/minus one standard deviation elastic response spectra of synthetic ground motions, pertaining to a variety of different earthquake scenarios, are compared to the associated response spectra computed by the NGA-West2 ground motion prediction equations and found to be in excellent agreement.
      PubDate: 2017-10-26T01:31:39.704349-05:
      DOI: 10.1002/eqe.2948
       
  • Probabilistic performance-based optimum design of seismic isolation for a
           California high-speed rail prototype bridge
    • Authors: Yong Li; Joel P. Conte
      Abstract: Previous comparison studies on seismic isolation have demonstrated its beneficial and detrimental effects on the structural performance of high-speed rail bridges during earthquakes. Striking a balance between these 2 competing effects requires proper tuning of the controlling design parameters in the design of the seismic isolation system. This results in a challenging problem for practical design in performance-based engineering, particularly when the uncertainty in seismic loading needs to be explicitly accounted for. This problem can be tackled using a novel probabilistic performance-based optimum seismic design (PPBOSD) framework, which has been previously proposed as an extension of the performance-based earthquake engineering methodology. For this purpose, a parametric probabilistic demand hazard analysis is performed over a grid in the seismic isolator parameter space, using high-throughput cloud-computing resources, for a California high-speed rail (CHSR) prototype bridge. The derived probabilistic structural demand hazard results conditional on a seismic hazard level and unconditional, i.e., accounting for all seismic hazard levels, are used to define 2 families of risk features, respectively. Various risk features are explored as functions of the key isolator parameters and are used to construct probabilistic objective and constraint functions in defining well-posed optimization problems. These optimization problems are solved using a grid-based, brute-force approach as an application of the PPBOSD framework, seeking optimum seismic isolator parameters for the CHSR prototype bridge. This research shows the promising use of seismic isolation for CHSR bridges, as well as the potential of the versatile PPBOSD framework in solving probabilistic performance-based real-world design problems.
      PubDate: 2017-10-19T22:16:12.683994-05:
      DOI: 10.1002/eqe.2976
       
  • Two-stage damage detection algorithms of structure using modal parameters
           identified from recursive subspace identification
    • Authors: Jun-Da Chen; Chin-Hsiung Loh
      Abstract: Structural damage assessment under external loading, such as earthquake excitation, is an important issue in structural safety evaluation. In this regard, appropriate data analysis and feature extraction techniques are required to interpret the measured data and to identify the state of the structure and, if possible, to detect the damage. In this study, the recursive subspace identification with Bona-fide LQ renewing algorithm (RSI-BonaFide-Oblique) incorporated with moving window technique is utilized to identify modal parameters such as natural frequencies, damping ratios, and mode shapes at each instant of time during the strong earthquake excitation. From which the least square stiffness method (LSSM) combined with the model updating technique, called efficient model correction method (EMCM), is used to estimate the first-stage system stiffness matrix using the simplified model from the previously identified modal parameters (nominal model). In the second stage, 2 different damage assessment algorithms related to the nominal system stiffness matrix were derived. First, the model updating technique, called EMCM, is applied to correct the nominal model by the newly identified modal parameters during the strong motion. Second, the element damage index can be calculated using element damage index method (EDIM) to quantify the damage extent in each element. Verification of the proposed methods through the shaking table test data of 2 different types of structures and a building earthquake response data is demonstrated to specify its corresponding damage location, the time of occurrence during the excitation, and the percentage of stiffness reduction.
      PubDate: 2017-10-11T21:16:29.281671-05:
      DOI: 10.1002/eqe.2980
       
  • Is rocking motion predictable'
    • Authors: J. A. Bachmann; M. Strand, M. F. Vassiliou, M. Broccardo, B. Stojadinović
      Abstract: An argument of engineers and researchers against the use of rocking as a seismic response modification technique is that the rocking motion of a structure is chaotic and the existing models are incapable of predicting it well. This argument is supported by the documented inability of rocking models to predict the motion of a specimen excited by a single ground motion. A statistical comparison of the experimental and the numerical responses of a rigid rocking oscillator not to a specific ground motion, but to ensembles of ground motions that have the same statistical properties, is presented. It is shown that the simple analytical model proposed by Housner in 1963 is capable of predicting the statistics of seismic response of a rigid rocking oscillator.
      PubDate: 2017-10-05T21:02:17.843428-05:
      DOI: 10.1002/eqe.2978
       
  • Estimation of inelastic displacement ratio for base-isolated structures
    • Authors: Saman Yaghmaei-Sabegh; Sina Safari, Karim Abdolmohammad Ghayouri
      Abstract: This study develops a straightforward approximate method to estimate inelastic displacement ratio, C1 for base-isolated structures subjected to near-fault and far-fault ground motions. Taking into account the inelastic behavior of isolator and superstructure, a 2 degrees of freedom model is employed. A total of 90 earthquake ground motions are selected and classified into different clusters according to the frequency content features of records represented by the peak ground acceleration to peak ground velocity ratio, Ap/Vp. A parametric study is conducted, and effective factors in C1 (i.e., fundamental vibration period of the superstructure, Ts; postyield stiffness ratio of the superstructure, αs; strength reduction ratio, R; vibration period of the isolator, Tb; strength of the isolator, Q; ratio of superstructure mass to total mass of the system, γm) are recognized. The results indicate that the practical range of C1 values could be expected for base-isolated structures. Subsequently, effective parameters are included in simple predictive equations. Finally, the accuracy of the proposed approximate equations is evaluated and verified through error measurement, and comparisons are made in the analyses.
      PubDate: 2017-10-05T21:01:48.66627-05:0
      DOI: 10.1002/eqe.2983
       
  • Seismic behaviour of steel plate shear wall systems with staggered web
           configurations
    • Authors: Abhishek Verma; Dipti Ranjan Sahoo
      Abstract: Unstiffened steel plate shear walls (SPSWs) are used as lateral load-resisting systems in building structures. The energy dissipation mechanism of SPSWs consists of the tension yielding of web plates and the formation of plastic hinges at the ends of horizontal boundary elements. However, vertical boundary elements (VBEs) of high-rise SPSWs may experience high axial forces under lateral loading. This study explores the effectiveness of staggering of web plates on the reduction of VBE forces and drift response of SPSWs during an earthquake event. An analytical study has been conducted to determine the base shear reduction factor so as to match the overstrength of staggered systems with conventional SPSWs. A design methodology has been proposed for staggered SPSWs. Six-, 9-, and 20-storey staggered and conventional SPSWs with varying aspect ratios are considered in this study to compare their seismic response. These study frames are modelled and analysed in OpenSEES platform. Nonlinear static and dynamic analyses are performed to compare the drift response, hinge mechanisms, and steel tonnage. Staggered SPSWs showed uniform drift distribution and reduction in interstorey drift and axial force demand on the VBEs.
      PubDate: 2017-10-05T21:01:20.229129-05:
      DOI: 10.1002/eqe.2984
       
  • An experimental study of a damage-controllable plastic-hinge-supported
           wall structure
    • Authors: Xiaoting Wang; Tao Wang, Zhe Qu
      Abstract: The reinforced concrete (RC) shear wall serves as one of the most important components sustaining lateral seismic forces. Although they allow advanced seismic performance to be achieved, RC shear walls are rather difficult to repair once the physical plastic hinge at the bottom part has been formed. To overcome this, a damage-controllable plastic hinge with a large energy dissipation capacity is developed herein, in which the sectional forces are decoupled and sustained separately by different components. The components sustaining the axial and the shear forces all remain elastic even under a rarely occurred earthquake, while the bending components yield and dissipate seismic energy during a design-level earthquake. This design makes the behavior of the system more predictable and thus more easily customizable to different performance demands. Moreover, the energy dissipation components can be conveniently replaced to fully restore the occupancy function of a building. To examine the seismic behavior of the newly developed component, 3 one third-scale specimens were tested quasi-statically, including 1 RC wall complying with the current design codes of China and 2 installed with the damage-controllable plastic hinges. Each wall was designed to have the same strength. The experimental results demonstrated that the plastic-hinge-supported walls had a better energy dissipation capacity and damage controllability than the RC specimen. Both achieved drift ratios greater than 3% under a steadily increasing lateral force.
      PubDate: 2017-10-04T03:46:25.112783-05:
      DOI: 10.1002/eqe.2981
       
  • On-line hybrid test method for evaluating the performance of structural
           details to failure
    • Authors: Konstantinos A. Skalomenos; Masahiro Kurata, Masayoshi Nakashima
      Abstract: A test environment to evaluate the seismic performance of gusset plate connections intended for steel braced frames is proposed. The developed test method combines the substructuring techniques with finite element analysis methods in an on-line hybrid scheme. Numerical substructure analysis is conducted on bracing members, while bracing connections are treated as experimental substructures. A force-displacement combined control imposed with the aid of 2 jacks ensures physical continuity between the analysis and test. The rotational behavior of gusset plate connections subjected to large inelasticity and varying axial loading until fracture is investigated. Two gusset plate details were designed and tested to verify the efficiency of the proposed method. The test method is rational, and smooth operation is achieved. The test results revealed the advantage of the developed on-line hybrid test method in exploring the ultimate capacity of bracing connections.
      PubDate: 2017-09-29T11:06:27.839469-05:
      DOI: 10.1002/eqe.2979
       
  • Dynamic buckling of braces in concentrically braced frames
    • Authors: Sina Kazemzadeh Azad; Cem Topkaya, Milad Bybordiani
      Abstract: Axially loaded members might experience compressive forces above their static buckling capacity because of dynamic buckling under rapid shortening. Although the subject is studied in the context of engineering mechanics, it has not been thoroughly investigated in the field of earthquake engineering. Such dynamic overshoots in the compressive capacity can also be observed for braces of concentrically braced frames (CBFs) during earthquakes. Consequently, a comprehensive investigation is conducted in this study regarding the effects of dynamic buckling of braces on the seismic behavior of steel CBFs. After providing a theoretical background, recent dynamic experiments on braces and CBFs are simulated and discussed to investigate the occurrence of dynamic overshoot during these tests. Eight archetype CBFs are then designed, modeled, and subjected to a large set of ground motions to provide a quantified insight on the frequency and anticipated level of dynamic overshoot in the compressive capacity of braces during earthquakes. Results of a total of 1600 nonlinear time history analyses revealed that dynamic overshoots occur frequently in braces and affect the behavior of CBFs notably. Considerable increases are recorded in forces transmitted to other members of CBFs as a consequence of such dynamic overshoots. Importance of incorporating these dynamic overshoots in the capacity design procedure of columns, beams, and gusset plates is highlighted. Furthermore, results of a parametric study are presented and summarized in the form of a simple formula that can be used as a guide for estimating the level of dynamic overshoot.
      PubDate: 2017-09-26T21:11:32.057826-05:
      DOI: 10.1002/eqe.2982
       
  • Model for multiblock columns subjected to base excitation
    • Authors: Tamás Ther; László P. Kollár
      Abstract: A new model is presented for multiblock columns subjected to earthquakes, which contains an impact and an opening model. Both in the impact and in the opening model, all the possible opening configurations are investigated because it was found that in many practical cases, unexpected patterns may occur. The model is purely mechanical: assuming rigid blocks and classical (inelastic) impact. The effect of energy dissipation during impact was investigated. Using our model in accordance with the literature, it was found that monolithic blocks are more vulnerable to overturning than multiblock systems.
      PubDate: 2017-09-21T22:31:30.792629-05:
      DOI: 10.1002/eqe.2957
       
  • 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
       
  • 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
       
  • 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
       
  • Issue Information
    • Pages: 2637 - 2638
      Abstract: No abstract is available for this article.
      PubDate: 2017-11-02T21:03:36.366152-05:
      DOI: 10.1002/eqe.2824
       
 
 
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