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CIVIL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 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: 36)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
Agregat     Open Access  
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 31)
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: 16)
Building & Management     Open Access  
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: 6)
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: 18)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Civil Engineering Infrastructures Journal     Open Access  
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 268)
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: 17)
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: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
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: 6)
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: 7)
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: 8)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Engineering, Science and Technology     Open Access  
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: 14)
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)
Journal of Water and Environmental Nanotechnology     Open Access  
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)
npj Materials Degradation     Open Access  
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: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 12)
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: 11)
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: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 12)
Structural Mechanics of Engineering Constructions and Buildings     Open Access  
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: 9)
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]   [17 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  [1589 journals]
  • Modeling spatially correlated spectral accelerations at multiple periods
           using principal component analysis and geostatistics
    • Authors: Maryia Markhvida; Luis Ceferino, Jack W. Baker
      Abstract: Regional seismic risk assessments and quantification of portfolio losses often require simulation of spatially distributed ground motions at multiple intensity measures. For a given earthquake, distributed ground motions are characterized by spatial correlation and correlation between different intensity measures, known as cross-correlation. This study proposes a new spatial cross-correlation model for within-event spectral acceleration residuals that uses a combination of principal component analysis (PCA) and geostatistics. Records from 45 earthquakes are used to investigate earthquake-to-earthquake trends in application of PCA to spectral acceleration residuals. Based on the findings, PCA is used to determine coefficients that linearly transform cross-correlated residuals to independent principal components. Nested semivariogram models are then fit to empirical semivariograms to quantify the spatial correlation of principal components. The resultant PCA spatial cross-correlation model is shown to be accurate and computationally efficient. A step-by-step procedure and an example are presented to illustrate the use of the predictive model for rapid simulation of spatially cross-correlated spectral accelerations at multiple periods.
      PubDate: 2018-01-14T23:55:43.813241-05:
      DOI: 10.1002/eqe.3007
  • Experimental and numerical behaviour of dissipative devices based on
           carbon-wrapped steel tubes for the retrofitting of existing precast RC
    • Authors: Andrea Vittorio Pollini; Nicola Buratti, Claudio Mazzotti
      Abstract: The 2012 Emilia earthquake (in Northern Italy) caused extensive damage to existing prefabricated reinforced concrete structures. These buildings were found being extremely vulnerable because, being designed for vertical loads only, they featured friction-based connections between structural elements, most commonly between beams and columns. Given the large diffusion of these structures, their seismic retrofit is critical. Various techniques have been proposed in the literature, in most of which friction-based connections are removed by inserting mechanical connectors that will make beam-column connections hinged. These approaches lead to a significant increase of the base shear and therefore require strengthening of columns.The paper presents dissipative devices based on carbon-wrapped steel tubes to be used as an alternative low-damage solution for the retrofit of beam-column connections. The first part of the paper presents results of experimental tests on the devices and discusses their dissipative behaviour. The succeeding parts of the paper present numerical analyses on simple structures reinforced with the proposed device. The results of the numerical study show how the introduction of the dissipative devices produces a significant reduction of forces transmitted to the structure, by comparing the seismic response of simple frame structures equipped with dissipative devices with the response of equivalent elastic systems.
      PubDate: 2018-01-08T22:36:35.706832-05:
      DOI: 10.1002/eqe.3017
  • Seismic performance and damage evaluation of a waffle-flat plate structure
           with hysteretic dampers through shake-table tests
    • Authors: Amadeo Benavent-Climent; Jesús Donaire-Avila, Elena Oliver-Sáiz
      Abstract: Reinforced concrete waffle-flat plate (WFP) structures present 2 important drawbacks for use as a main seismic resisting system: low lateral stiffness and limited ductility. Yet the former can serve a positive purpose when, in parallel, the flexible WFP structure is combined with a stiff system lending high-energy dissipation capacity, to form a “flexible-stiff mixed structure.” This paper experimentally investigates the seismic performance of WFP structures (flexible system) equipped with hysteretic dampers (stiff system) through shake-table tests conducted on a 2/5-scale test specimen. The WFP structure was designed only for gravitational loads. The lateral strength and stiffness provided by the dampers at each story were, respectively, about 3 and 7 times greater than those of the bare WFP structure. The mixed system was subjected to a sequence of seismic simulations representing frequent to very rare ground motions. Under the seismic simulations associated with earthquakes having return periods ranging from 93 to 1894 years, the WFP structure performed in the level of “immediate occupancy,” with maximum interstory drifts up to about 1%. The dampers dissipated most (75%) of the energy input by the earthquake.
      PubDate: 2018-01-03T21:22:13.650539-05:
      DOI: 10.1002/eqe.3016
  • Can ground densification improve seismic performance of the
           soil-foundation-structure system on liquefiable soils'
    • Authors: Juan Olarte; Shideh Dashti, Abbie B. Liel
      Abstract: Over the past few decades, soil densification has been widely employed to reduce the liquefaction hazard or consequences on structures. The decision to mitigate and the design of densification specifications are typically based on procedures that assume free-field conditions or experience. As a result, the influence of ground densification on the performance of structures and the key mechanisms of soil-structure interaction remains poorly understood. This paper presents results of four centrifuge tests to evaluate the performance of 3- and 9-story, potentially inelastic structures on liquefiable ground with and without densification. Densification was shown to generally reduce the net excess pore pressures and foundation permanent settlements (although not necessarily to acceptable levels), while amplifying the accelerations on the foundation. The influence of these demands on the performance of the foundation and superstructure depended on the structure's strength and dynamic properties, as well as ground motion characteristics. In addition, densification tended to amplify the moment demand at the beam and column connections, which increased permanent flexural deformations and P-Δ effects (particularly on the heavier and weaker structure) that could have an adverse effect on foundation rotation. The experimental results presented aim to provide insight into the potential tradeoffs of ground densification, which may reduce foundation permanent settlement, but amplify shaking intensity that can result in larger foundation rotation, flexural drifts, and damage to the superstructure, if not considered in design. These considerations are important for developing performance-based strategies to design mitigation techniques that improve performance of the soil-foundation-structure system in a holistic manner.
      PubDate: 2018-01-03T06:33:18.517406-05:
      DOI: 10.1002/eqe.3012
  • Filtering action of embedded massive foundations: New analytical
           expressions and evidence from 2 instrumented buildings
    • Authors: Riccardo Conti; Marco Morigi, Emmanouil Rovithis, Nikos Theodoulidis, Christos Karakostas
      Abstract: This paper deals with the effect of the foundation mass on the filtering action exerted by embedded foundations. The system under examination comprises a rigid rectangular foundation embedded in a homogeneous isotropic viscoelastic half-space under harmonic shear waves propagating vertically. The problem is addressed both theoretically and numerically by means of a hybrid approach, where the foundation mass is explicitly included in the kinematic interaction between the foundation and the surrounding soil, thus referring to a “quasi-kinematic” interaction problem. Based on the results of an extensive parametric study, it is shown that the filtering problem depends essentially on three dimensionless parameters, i.e.: the dimensionless frequency of the input motion, the foundation width-to-embedment depth ratio, and the foundation-to-soil mass density ratio. In complements to the translational and rotational kinematic interaction factors that are commonly adopted to quantify the filtering effect of rigid massless foundations on the free-field motion, an additional kinematic interaction factor is introduced, referring to the horizontal motion at the top of a rigid massive foundation. New analytical expressions for the above kinematic interaction factors are proposed and compared with foundation-to-free-field transfer functions computed from available earthquake recordings on two instrumented buildings in LA (California) and Thessaloniki (Greece). Results indicate that the foundation mass can have a strong beneficial effect on the filtering action with increasing foundation-to-soil mass density and foundation width-to-embedment depth ratios.
      PubDate: 2018-01-03T06:32:18.650099-05:
      DOI: 10.1002/eqe.3014
  • Information theory measures for the engineering validation of
           ground-motion simulations
    • Authors: Alexandra Tsioulou; Carmine Galasso
      Abstract: This short communication introduces a quantitative approach for the engineering validation of ground-motion simulations based on information theory concepts and statistical hypothesis testing. Specifically, we use the Kullback-Leibler divergence to measure the similarity of the probability distributions of recorded and simulated ground-motion intensity measures (IMs). We demonstrate the application of the proposed validation approach to ground-motion simulations computed by using a variety of methods, including Graves and Pitarka hybrid broadband, the deterministic composite source model, and a stochastic white noise finite-fault model. Ground-motion IMs, acting as proxies for the (nonlinear) seismic response of more complex engineered systems, are considered herein to validate the considered ground-motion simulation methods. The list of considered IMs includes both spectral-shape and duration-related proxies, shown to be the optimal IMs in several probabilistic seismic demand models of different structural types, within the framework of performance-based earthquake engineering. The proposed validation exercise (1) can highlight the similarities and differences between simulated and recorded ground motions for a given simulation method and/or (2) allow the ranking of the performance of alternative simulation methods. The similarities between records and simulations should provide confidence in using the simulation method for engineering applications, while the discrepancies should help in improving the tested method for the generation of synthetic records.
      PubDate: 2018-01-03T06:31:53.255086-05:
      DOI: 10.1002/eqe.3015
  • Issue Information
    • Pages: 267 - 268
      Abstract: No abstract is available for this article.
      PubDate: 2018-01-05T00:48:37.10778-05:0
      DOI: 10.1002/eqe.2959
  • Seismic response of a wobbling 3D frame
    • Authors: Michalis F. Vassiliou
      Abstract: This paper investigates the 3D response of a slab supported by wobbling columns. The columns are not allowed neither to slide nor to roll out of their initial position. An analytical model is proposed, the equations of motion are derived, and they are solved numerically. The paper concludes that the addition of the slab makes the columns more stable. In fact, the system is almost equivalent to the response of a solitary column with the same aspect ratio yet larger size. However, it is also shown that the system is less stable than its planar counterpart and that planar analysis can only qualitatively describe the behavior of 3D structures. A case study shows that the concept could be used as a seismic isolation technique for bridges. However, more research need to be performed on defining proper intensity measures for uplifting structures, as it is shown that there is large record-to-record variability, even when intensity measures developed for rocking structures are used.
      PubDate: 2017-12-28T04:28:58.39819-05:0
      DOI: 10.1002/eqe.3013
  • Seismic drift demands in multi-storey cross-laminated timber buildings
    • Authors: Cagatay Demirci; Christian Málaga-Chuquitaype, Lorenzo Macorini
      Abstract: This paper investigates the seismic response of multi-storey cross-laminated timber (CLT) buildings and its relationship with salient ground-motion and building characteristics. Attention is given to the effects of earthquake frequency content on the inelastic deformation demands of platform CLT walled structures. The response of a set of 60 CLT buildings of varying number of storeys and panel fragmentation levels representative of a wide range of structural configurations subjected to 1656 real earthquake records is examined. It is shown that, besides salient structural parameters like panel aspect ratio, design behaviour factor, and density of joints, the frequency content of the earthquake action as characterized by its mean period has a paramount importance on the level of nonlinear deformations attained by CLT structures. Moreover, the evolution of drifts as a function of building to ground-motion periods ratio is different for low- and high-rise buildings. Accordingly, nonlinear regression models are developed for estimating the global and interstorey drifts demands on multi-storey CLT buildings. Finally, the significance of the results is highlighted with reference to European seismic design procedures and recent assessment proposals.
      PubDate: 2017-12-28T04:28:06.019742-05:
      DOI: 10.1002/eqe.3003
  • An enhanced base isolation system equipped with optimal tuned mass damper
           inerter (TMDI)
    • Authors: Dario De Domenico; Giuseppe Ricciardi
      Abstract: In seismic base isolation, most of the earthquake-induced displacement demand is concentrated at the isolation level, thereby the base-isolation system undergoes large displacements. In an attempt to reduce such displacement demand, this paper proposes an enhanced base-isolation system incorporating the inerter, a 2-terminal flywheel device whose generated force is proportional to the relative acceleration between its terminals. The inerter acts as an additional, apparent mass that can be even 200 times higher than its physical mass. When the inerter is installed in series with spring and damper elements, a lower-mass and more effective alternative to the traditional tuned mass damper (TMD) is obtained, ie, the TMD inerter (TMDI), wherein the device inertance plays the role of the TMD mass. By attaching a TMDI to the isolation floor, it is demonstrated that the displacement demand of base-isolated structures can be significantly reduced. Due to the stochastic nature of earthquake ground motions, optimal parameters of the TMDI are found based on a probabilistic framework. Different optimization procedures are scrutinized. The effectiveness of the optimal TMDI parameters is assessed via time history analyses of base-isolated multistory buildings under several earthquake excitations; a sensitivity analysis is also performed. The enhanced base-isolation system equipped with optimal TMDI attains an excellent level of vibration reduction as compared to the conventional base-isolation scheme, in terms not only of displacement demand of the base-isolation system but also of response of the isolated superstructure (eg, base shear and interstory drifts); moreover, the proposed vibration control strategy does not imply excessive stroke of the TMDI.
      PubDate: 2017-12-28T04:27:22.022243-05:
      DOI: 10.1002/eqe.3011
  • Cloud to IDA: Efficient fragility assessment with limited scaling
    • Authors: Andrea Miano; Fatemeh Jalayer, Hossein Ebrahimian, Andrea Prota
      Abstract: Incremental dynamic analysis (IDA) leads to curves expressed in terms of structural response versus intensity, commonly known as the IDA curves. It is known that implementation of IDA usually involves significant computational effort and most often significant scaling of the original records to various intensity levels. Employing as the performance variable the critical demand to capacity ratio (DCR) throughout the structure, which is equal to unity at the onset of the limit state, facilitates the identification of the intensity values at the onset of a desired limit state and hence the implementation of the IDA procedure. Employing the structural response to un-scaled records and the corresponding regression-based response predictions (a.k.a., the “Cloud Analysis”) helps in identifying the range of intensity values corresponding to demand to capacity ratio values in the vicinity of unity. The Cloud to IDA procedure for structural fragility assessment is proposed on the premise of exploiting the Cloud Analysis results to obtain the IDA curves both with minimum number of analyses and minimum amount of scaling. The transverse frame of a shear-critical 7-story older RC building in Van Nuys, CA, which is modeled in Opensees with fiber-section considering the flexural-shear-axial interactions and the bar slip, is employed as a case study. It is demonstrated, by comparing the results to IDA and other state of the art non-linear dynamic procedures based on no scaling or spectral-shape-compatible scaling, that the Cloud to IDA procedure leads to reliable results in terms of structural fragility and risk for the prescribed limit state.
      PubDate: 2017-12-26T23:25:47.333152-05:
      DOI: 10.1002/eqe.3009
  • Interbuilding interpolation of peak seismic response using spatially
           correlated demand parameters
    • Authors: Han Sun; Henry Burton, Yu Zhang, John Wallace
      Abstract: Seismic structural responses recorded in instrumented buildings during an earthquake are used to provide insights into the demands placed on neighboring, noninstrumented buildings, using a framework to interpolate structural response demands across buildings. The interbuilding interpolation model relies on the spatial and structural correlations of responses in coregionally located buildings subjected to a seismic event. A dataset of response demands for a portfolio of reinforced concrete moment frame buildings is generated by performing nonlinear response history analyses on structural models using ground motions recorded from historical scenario earthquakes. The dataset is used to characterize the correlation between seismic demands across different buildings. Semivariograms are used to model spatial and structural correlations and then incorporated into a kriging algorithm, which forms the basis of the interpolation models. The effect of several model and dataset attributes and assumptions, for example, using intensity-measure-based versus engineering demand parameter-based semivariograms, and size of training dataset relative to portfolio, on the overall performance are evaluated along with the limitations of the proposed model.
      PubDate: 2017-12-18T22:23:31.658027-05:
      DOI: 10.1002/eqe.3010
  • Evaluation of ASCE 7 equations for designing acceleration-sensitive
           nonstructural components using data from instrumented buildings
    • Authors: Hamidreza Anajafi; Ricardo A. Medina
      Abstract: This study uses instrumented buildings and models of code-based designed buildings to validate the results of previous studies that highlighted the need to revise the ASCE 7 Fp equation for designing nonstructural components (NSCs) through utilizing oversimplified linear and nonlinear models. The evaluation of floor response spectra of a large number of instrumented buildings illustrates that, unlike the ASCE 7 approach, the in-structure and the component amplification factors are a function of the ratio of NSC period to the supporting building modal periods, the ground motion intensity, and the NSC location. It is also shown that the recorded ground motions at the base of instrumented buildings in most cases are significantly lower than design earthquake (DE) ground motions. Because ASCE 7 is meant to provide demands at a DE level, for a more reliable evaluation of the Fp equation, 2 representative archetype buildings are designed based on the ASCE 7-16 seismic provisions and exposed to various ground motion intensity levels (including those consistent with the ones experienced by instrumented buildings and the DE). Simulation results of the archetype buildings, consistent with previous numerical studies, illustrate the tendency of the ASCE 7 in-structure amplification factor, [1 + 2(z/h)], to significantly overestimate demands at all floor levels and the ASCE 7 limit of ap=212 to in many cases underestimate the calculated NSC amplification factors. Furthermore, the product of these 2 amplification factors (that represents the normalized peak NSC acceleration) in some cases exceeds the ASCE 7 equation by a factor up to 1.50.
      PubDate: 2017-12-18T22:22:59.084757-05:
      DOI: 10.1002/eqe.3006
  • Frequency-dependent principal component analysis of multicomponent
           earthquake ground motions
    • Authors: Sandip Das; Budhaditya Hazra
      Abstract: Stochastic ground motion simulation techniques are becoming increasingly popular because of enhanced computation power enabling direct simulation of complex response quantities. Priestley process assumption is the most general approach for stochastic modeling of earthquake ground motion. However, a framework for multicomponent ground motion simulation using the general Priestley process assumption is not available. Multicomponent motions are useful especially when the correlation structure between them significantly influences the response. The present study proposes a framework for frequency-dependent principal component analysis (PCA), which facilitates Priestley process–based simulation of multicomponent ground motions. The study focuses only on the frequency-dependent PCA part, and the results show high dependency of the principal components/directions on the frequency bands of the signals. The present work also advocates that the frequency-dependent PCA should be preferred to the conventional PCA as the former can address the issues related to the frequency-independent uniform modulation associated with the latter.
      PubDate: 2017-12-18T00:06:21.086022-05:
      DOI: 10.1002/eqe.3008
  • Linear-elastic lateral load analysis and seismic design of pin-supported
           wall-frame structures with yielding dampers
    • Authors: Tianshu Sun; Yahya C. Kurama, Peizhou Zhang, Jinping Ou
      Abstract: This paper describes an analytical investigation on a reinforced concrete lateral load resisting structural system comprising a pin-supported (base-rocking) shear wall coupled with a moment frame on 1 or both sides of the wall. Yielding dampers are used to provide supplemental energy dissipation through the relative displacements at the vertical connections between the wall and the frames. The study extends a previous linear-elastic model for pin-supported wall-frame structures by including the effects of the dampers. A closed-form solution of the lateral load behavior of the structure is derived by approximating the discrete wall-frame-damper interactions with distributed (ie, continuous) properties. The validity of the model is verified by comparing the closed-form results with computational models using OpenSees program. Then, a parametric analysis is conducted to investigate the effects of the wall, frame, and damper stiffness on the behavior of the structure. It is found that the damper stiffness significantly affects the distribution of shear forces and bending moments over the wall height. Finally, the performance-based plastic design approach extended to the wall-frame-damper system is proposed. Case studies are carried out to design 2 damped pin-supported wall-frame structures using the proposed approach. Nonlinear dynamic time-history analyses are conducted to verify the effectiveness of this method. Results indicate that the designed structures can achieve the performance level with the story drift ratios less than target values, and weak-story failure mechanism is not observed. The approach can be used in engineering applications.
      PubDate: 2017-12-13T02:57:06.455088-05:
      DOI: 10.1002/eqe.3002
  • A multidirectional conditional spectrum
    • Authors: Cecilia Nievas; Timothy Sullivan
      Abstract: This paper presents a procedure to generate multidirectional conditional spectra (MDCS) that allow for the characterisation of seismic demands at different angles of incidence. Being conditional on a particular period and its direction of maximum response, it is considered to be a natural evolution of the conditional spectrum to account for the effects of directionality, that is, the variation of seismic demands as a function of the angle of incidence of ground motions, which can have a significant effect on the performance of different kinds of structures. The three main components needed for the generation of MDCS are explained in detail. Monte Carlo simulations are conducted using different sampling methods to assess the effects of incorporating the correlation between demands at different orientations for the same oscillator period, and a novel correlation model is proposed for this purpose. The statistical characteristics of MDCS, their relation with the conditional spectrum, the advantages of the MDCS over previous definitions of orientation-specific spectra, and prospective future developments are discussed.
      PubDate: 2017-12-07T23:19:40.632701-05:
      DOI: 10.1002/eqe.3000
  • Quantification of modelling uncertainty in existing Italian RC frames
    • Authors: Gerard J. O'Reilly; Timothy J. Sullivan
      Abstract: Assessment of the seismic performance of existing structures requires due consideration of both aleatory and epistemic sources of uncertainty; the former being typically associated with the randomness in ground motion records and the latter with the uncertainty in numerical modelling. Using a numerical modelling approach calibrated to available experimental test data collected from the literature, the uncertainty associated with different modelling parameters for existing reinforced concrete frames in Italy was quantified via an extensive numerical study. This was done to quantify the propagation of modelling parameter type uncertainty to the overall dispersion of the demand parameters typically used in seismic assessment, namely peak storey drift and peak floor accelerations. In addition, the impact of such modelling uncertainty on the median intensity and dispersion of the collapse fragility function was also examined. From the results of this study, empirical values of modelling parameter uncertainty were quantified with a view to being used in the assessment of existing reinforced concrete frames with masonry infill designed prior to the introduction of seismic design provisions in Italy during the 1970s. Comparing these empirical values to those available in the literature, it is seen how the fundamental behaviour of the frames differs from more modern frames with ductile detailing to the extent that values available in guidelines such as FEMA P58 cannot be reasonably adopted for these structural typologies.
      PubDate: 2017-12-07T23:17:52.032447-05:
      DOI: 10.1002/eqe.3005
  • Permanent earthquake-induced actions in buried pipelines: Numerical
           modeling and experimental verification
    • Authors: Gregory C. Sarvanis; Spyros A. Karamanos, Polynikis Vazouras, Elisabetta Mecozzi, Antonio Lucci, Panos Dakoulas
      Abstract: Buried pipelines are often constructed in seismic and other geohazard areas, where severe ground deformations may induce severe strains in the pipeline. Calculation of those strains is essential for assessing pipeline integrity, and therefore, the development of efficient models accounting for soil-pipe interaction is required. The present paper is aiming at developing efficient tools for calculating ground-induced deformation on buried pipelines, often triggered by earthquake action, in the form of fault rupture, liquefaction-induced lateral spreading, soil subsidence, or landslide. Soil-pipe interaction is investigated by using advanced numerical tools, which employ solid elements for the soil, shell elements for the pipe, and account for soil-pipe interaction, supported by large-scale experiments. Soil-pipe interaction in axial and transverse directions is evaluated first, using results from special-purpose experiments and finite element simulations. The comparison between experimental and numerical results offers valuable information on key material parameters, necessary for accurate simulation of soil-pipe interaction. Furthermore, reference is made to relevant provisions of design recommendations. Using the finite element models, calibrated from these experiments, pipeline performance at seismic-fault crossings is analyzed, emphasizing on soil-pipe interaction effects in the axial direction. The second part refers to full-scale experiments, performed on a unique testing device. These experiments are modeled with the finite element tools to verify their efficiency in simulating soil-pipe response under landslide or strike-slip fault movement. The large-scale experimental results compare very well with the numerical predictions, verifying the capability of the finite element models for accurate prediction of pipeline response under permanent earthquake-induced ground deformations.
      PubDate: 2017-12-03T22:51:38.306573-05:
      DOI: 10.1002/eqe.3001
  • Experimental study of deformable connection consisting of friction device
           and rubber bearings to connect floor system to lateral force resisting
    • Authors: Georgios Tsampras; Richard Sause, Robert B. Fleischman, José I. Restrepo
      Abstract: This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and thereby to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a friction device (FD) and carbon fiber-reinforced laminated low-damping rubber bearings (RB), denoted as the FD + RB connection.The test results show that the force-deformation responses of the FD + RB connection are stable under quasi-static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD + RB connection force-deformation response is approximated with a bilinear elastic-plastic force-deformation response with kinematic hardening. The FD is axially stiff, compact, easy-to-assemble, and able to accommodate the FD + RB connection kinematic requirements. The FD elastic stiffness controls the FD + RB connection elastic stiffness. The FD friction force controls the force when the FD + RB connection force-deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post-elastic stiffness to the FD + RB connection. The machining tolerances for the FD components, the “break-in” effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12-story reinforced concrete wall building with FD + RB connections under seismic loading show that a reduction of the FD friction force increases the FD + RB connection deformation demand.
      PubDate: 2017-11-29T06:42:32.700781-05:
      DOI: 10.1002/eqe.3004
  • Empirical-based out-of-plane URM infill wall model accounting for the
           interaction with in-plane demand
    • Authors: Paolo Ricci; Mariano Di Domenico, Gerardo M. Verderame
      Abstract: The role of masonry infills in the seismic behavior of reinforced concrete buildings has been widely studied in terms of their strength and stiffness contribution in the in-plane (IP) direction, while fewer studies have been carried out on their response and modeling in the out-of-plane (OOP) direction. In this paper, the state of the art in code and literature provisions regarding infills' OOP capacity and seismic demand is presented, together with a review of the experimental tests that have been carried out to investigate infills' OOP behavior and the effects of IP-OOP interaction. This review aims to collect an experimental database that is used to evaluate the effectiveness of literature and code provisions and to propose a semiempirical approach both for predicting infills' OOP strength, stiffness, and displacement capacity and for modeling the effects of IP displacement demand on OOP behavior and vice versa. Then, the state of the art on modeling of infills' OOP behavior and IP-OOP interaction is presented together with a new macro model based on the proposed formulations and conceived to represent the IP and OOP behavior by taking into account the mutual interaction effects. Finally, the proposed model is used for an example application on two case-study buildings, showing the effects of taking into account or neglecting the IP-OOP interaction phenomena.
      PubDate: 2017-11-26T23:42:12.06187-05:0
      DOI: 10.1002/eqe.2992
  • Optimum dynamic characteristic control approach for building mass damper
    • Authors: Shiang-Jung Wang; Bo-Han Lee, Wei-Chu Chuang, Kuo-Chun Chang
      Abstract: A new seismic design manner, namely building mass damper (BMD), which is inspired from a combination of mid-story isolation and tuned mass damper design concepts, recently attracts immense attention. It is mainly because that the use of partial structural mass of the building as an energy absorber in the BMD design can overcome the drawback of limited response reduction due to insufficient added tuned mass in the conventional tuned mass damper design. In this study, an optimum BMD (OBMD) design approach, namely optimum dynamic characteristic control approach, based on a simplified 3-lumped-mass structure model is proposed to seismically protect both the superstructure (or tuned mass) and the substructure (or primary structure), respectively, above and below the control layer. A series of sensitivity analyses and experimental studies on different parameters, including mass, frequency, and damping ratios, of a building model designed with a BMD system were conducted. The test results verify the practical feasibility of the BMD concept as well as the effectiveness of the proposed OBMD design. Furthermore, by comparing with the numerical results of a mid-story isolated counterpart, it is demonstrated that the proposed OBMD design can have a comparable and even better control performance.
      PubDate: 2017-11-24T02:27:03.988445-05:
      DOI: 10.1002/eqe.2995
  • Composite periodic foundation and its application for seismic isolation
    • Authors: Z.B. Cheng; Z.F. Shi
      Abstract: This paper proposes a novel multidimensional composite periodic foundation for seismic isolation. The composite periodic foundation achieves multidimensional attenuation by innovative arrangement of periodic structures and taking advantage of the directional attenuation zone of periodic structures. Directional attenuation zones of periodic structures are derived for the in-plane wave, and the impact of geometrical parameters of the periodic structure on the characteristics of the directional attenuation zones is studied. The effectiveness of the proposed composite periodic foundation is demonstrated through application in seismic isolation for nuclear power plant structures. Harmonic analysis and time history analysis results show that the proposed composite periodic foundation with low-frequency directional attenuation zones can effectively reduce vibrations of the upper structure in both horizontal and vertical directions.
      PubDate: 2017-11-24T02:26:34.214324-05:
      DOI: 10.1002/eqe.2999
  • Real-time force control for servo-hydraulic actuator systems using
           adaptive time series compensator and compliance springs
    • Authors: Yunbyeong Chae; Ramin Rabiee, Abdullah Dursun, Chul-Young Kim
      Abstract: Servo-hydraulic actuators have been widely used for experimental studies in engineering. They can be controlled in either displacement or force control mode depending on the purpose of a test. It is necessary to control the actuators in real time when the rate-dependency effect of a test specimen needs to be accounted for under dynamic loads. Real-time hybrid simulation (RTHS) and effective force testing (EFT) method, which can consider the rate-dependency effect, have been known as viable alternatives to the shake table testing method. Due to the lack of knowledge in real-time force control, however, the structures that can be tested with RTHS and EFT are fairly limited. For instance, satisfying the force boundary condition for axially stiff members is a challenging task in RTHS, while EFT has a difficulty to be implemented for nonlinear structures. In order to resolve these issues, this paper introduces new real-time force control methods utilizing the adaptive time series (ATS) compensator and compliance springs. Unlike existing methods, the proposed force control methods do not require the structural modeling of a test structure, making it easy to be implemented especially for nonlinear structures. The force tracking performance of the proposed methods is evaluated for a small-scale steel mass block system with a magneto-rheological damper subjected to various target forces. Accuracy, time delay, and resonance response of these methods are discussed along with their force control performance for an axially stiff member. Overall, a satisfactory force tracking performance was observed by using the proposed force control methods.
      PubDate: 2017-11-24T02:25:55.642482-05:
      DOI: 10.1002/eqe.2994
  • An efficient algorithm for identifying pulse-like ground motions based on
           significant velocity half-cycles
    • Authors: Changhai Zhai; Cuihua Li, Sashi Kunnath, Weiping Wen
      Abstract: Ground motions with strong velocity pulses are of particular interest to structural earthquake engineers because they have the potential to impose extreme seismic demands on structures. Accurate classification of records is essential in several earthquake engineering fields where pulse-like ground motions should be distinguished from nonpulse-like records, such as probabilistic seismic hazard analysis and seismic risk assessment of structures. This study proposes an effective method to identify pulse-like ground motions having single, multiple, or irregular pulses. To effectively characterize the intrinsic pulse-like features, the concept of an energy-based significant velocity half-cycle, which is visually identifiable, is first presented. Ground motions are classified into 6 categories according to the number of significant half-cycles in the velocity time series. The pulse energy ratio is used as an indicator for quantitative identification, and then the energy threshold values for each type of ground motions are determined. Comprehensive comparisons of the proposed approach with 4 benchmark identification methods are conducted, and the results indicate that the methodology presented in this study can more accurately and efficiently distinguish pulse-like and nonpulse-like ground motions. Also presented are some insights into the reasons why many pulse-like ground motions are not detected successfully by each of the benchmark methods.
      PubDate: 2017-11-22T00:15:44.590333-05:
      DOI: 10.1002/eqe.2989
  • Critical uncertainty parameters influencing seismic performance of bridges
           using Lasso regression
    • Authors: Sujith Mangalathu; Jong-Su Jeon, Reginald DesRoches
      Abstract: Recent efforts of regional risk assessment of structures often pose a challenge in dealing with the potentially variable uncertain input parameters. The source of uncertainties can be either epistemic or aleatoric. This article identifies uncertain variables exhibiting strongest influences on the seismic demand of bridge components through various regression techniques such as linear, stepwise, Ridge, Lasso, and elastic net regressions. The statistical results indicate that Lasso regression is the most effective one in predicting the demand model as it has the lowest mean square error and absolute error. As the sensitivity study identifies more than 1 significant variable, a multiparameter fragility model using Lasso regression is suggested in this paper. The proposed fragility methodology is able to identify the relative impact of each uncertain input variable and level of treatment needed for these variables in the estimation of seismic demand models and fragility curves. Thus, the proposed approach helps bridge owners to spend their resources judiciously (e.g., data collection, field investigations, and censoring) in the generation of a more reliable database for regional risk assessment. This proposed approach can be applicable to other structures.
      PubDate: 2017-11-20T23:37:30.792264-05:
      DOI: 10.1002/eqe.2991
  • Ground motion selection for seismic slope displacement analysis using a
           generalized intensity measure distribution method
    • Authors: Wenqi Du; Gang Wang
      Abstract: Selecting ground motions based on the generalized intensity measure distribution (GIMD) approach has many appealing features, but it has not been fully verified in engineering practice. In this paper, several suites of ground motions, which have almost identical distributions of spectral acceleration (SA) ordinates but different distributions of non-SA intensity measures, are selected using the GIMD-based approach for a given earthquake scenario. The selected ground motion suites are used to compute the sliding displacements of various slopes. Comparisons of the resulting displacements demonstrate that selecting ground motions with biased distribution of some intensity measures (ie, Arias intensity) may yield systematic biases (up to 60% for some slope types). Therefore, compared to the ground motions selected based only on the distribution of SA ordinates, the ground motion suite selected by the GIMD-based approach can better represent the various characteristics of earthquake loadings, resulting in generally unbiased estimation in specific engineering applications.
      PubDate: 2017-11-20T23:37:14.799269-05:
      DOI: 10.1002/eqe.2998
  • Seismic energy dissipation under variable amplitude loading for
           rectangular RC members in flexure
    • Authors: Zhefeng Liu; Yukui Wang, Zhixiong Cao, Yuping Chen, Yi Hu
      Abstract: The energy dissipation characteristics of reinforced concrete members that exhibit both strength and stiffness deterioration under imposed displacement reversals were investigated. To do this, 24 symmetrically reinforced concrete rectangular specimens were tested under stable variable and random variable amplitude inelastic displacement cycles. Stable variable amplitude tests were employed to determine the low-cycle fatigue behavior of specimens where the loading sequence was the major variable. A 2-parameter fatigue model was developed in order to express the variation of the dissipated energy in displacement cycles with the cumulative hysteretic energy. This model was then used to predict the energy dissipation of test specimens subjected to random variable amplitude displacement cycles simulating severe seismic excitations. It has been demonstrated that the remaining energy dissipation capacity for the next displacement cycle was dependent on the relative relationship between the maximal displacement cycle and the energy dissipated along the completed displacement path. The plastic energy dissipation capacity of reinforced concrete members is both displacement path dependent and cumulative hysteretic energy dependent.
      PubDate: 2017-11-20T23:37:07.776538-05:
      DOI: 10.1002/eqe.2993
  • Online numerical simulation: A hybrid simulation method for incomplete
           boundary conditions
    • Authors: Bin Wu; Xizhan Ning, Guoshan Xu, Zhen Wang, Zhu Mei, Ge Yang
      Abstract: Hybrid simulation is a powerful and cost-effective simulation technique to evaluate structural dynamic performance. However, it is sometimes rather difficult to guarantee all the boundaries on the physical substructures, especially when the boundary conditions are very complex, due to limited laboratory resources. Lacking of boundary conditions is bound to change the stress state of the structure and eventually result in an inaccurate evaluation of structural performance. A model updating-based online numerical simulation method is proposed in this paper to tackle the problem of incomplete boundary conditions. In the proposed method, 2 sets of finite element models with the same constitutive model are set up for the overall analysis of the whole structure and the constitutive model parameter estimation of the physical substructure, respectively. The boundary conditions are naturally satisfied because the response is calculated from the overall structural model, and the accuracy is improved as the material constitutive parameters are updated. The effectiveness of the proposed method is validated via numerical simulations and actual hybrid tests on a RC frame structure, and the results show that the negative effect of incomplete boundary conditions is almost eliminated and the accuracy of hybrid simulation is very much improved.
      PubDate: 2017-11-20T23:36:07.601836-05:
      DOI: 10.1002/eqe.2996
  • Experimental study of the effect of restraining rim design on the extreme
           behavior of pendulum sliding bearings
    • Authors: Yu Bao; Tracy C. Becker, Takayuki Sone, Hiroki Hamaguchi
      Abstract: While the performance of sliding isolators has been extensively validated under typical levels of ground motion, there have been very few experimental studies on the extreme behavior of sliding isolation bearings when the displacement limit is reached. However, to appropriately design isolated systems, from selecting the displacement capacity of the bearing to sizing the superstructure members, the behavior of the bearing as it reaches, and in some cases exceeds, the displacement limit should be well understood. A series of shake table tests to investigate the extreme behavior of double pendulum sliding bearings under strong ground motions were conducted at McMaster University. One major difference in sliding bearings around the world is how the motion of the bearing is restrained at the bearing's displacement capacity. Scaled bearings with four different types of restraining rim designs were included, representing typical sliding restraining rims found in Europe, Japan, and the United States. Experimental observation shows that the restraining rim has a significant influence on the extreme behavior of sliding isolation bearing. Key response parameters such as impact force and uplift are evaluated and compared between the different sliding bearing designs. While the bearing with no rim bearing imparts the lowest forces to the superstructure, it loses its functionality at a lower amplitude input than all the other rim types. For the other rim designs, the impact forces are significantly higher but they remained operational although damaged.
      PubDate: 2017-11-19T22:21:57.508407-05:
      DOI: 10.1002/eqe.2997
  • 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
      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
    • 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
  • 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
    • 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
  • 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
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