{"title":"A codifiable methodology for estimating pallet sliding displacements on steel racking systems","authors":"Dimitrios Tsarpalis, Dimitrios Vamvatsikos","doi":"10.1002/eqe.4261","DOIUrl":"https://doi.org/10.1002/eqe.4261","url":null,"abstract":"<p>To facilitate the logistic processes within a modern warehouse, the contents of steel racking systems are not mechanically connected to the supporting beams, allowing a content-sliding mechanism to develop when static friction is exceeded. Given that the mass of contents is dominant, this is beneficial for limiting the apparent inertia. On the other hand, pallet fall-off may occur during strong seismic excitations, which is a failure mode that is not addressed by current seismic design processes and guidelines for racks. Along these lines, a codifiable methodology is proposed for estimating sliding displacements on steel racking systems, based on the statistical interpretation of a large set of response history analyses, using different rack configurations and ground motions. Firstly, a multi-parametric analysis is conducted using simplified rack models to (i) select the intensity measure and engineering demand parameter that can best describe the problem of pallet sliding and (ii) identify the salient rack characteristics that dominate sliding behavior. Thereafter, a series of multi-stripe analyses are performed using 180 rack realizations with different feature combinations to derive a so-called, Empirical Sliding Prediction Equation (ESPE) by following a three-step procedure: (a) perform regression on maximum sliding, (b) perform regression on the normalized sliding profile, and (c) combine steps a-b to derive the denormalized profile at a given confidence level. The proposed empirical relationships are then validated through a comparison between the observed and fitted sliding displacements in three rack case studies.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"363-388"},"PeriodicalIF":4.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4261","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhongwei Chen, T. Y. Yang, Yifei Xiao, Xiao Pan, Wanyan Yang
{"title":"Model reference adaptive hierarchical control framework for shake table tests","authors":"Zhongwei Chen, T. Y. Yang, Yifei Xiao, Xiao Pan, Wanyan Yang","doi":"10.1002/eqe.4256","DOIUrl":"https://doi.org/10.1002/eqe.4256","url":null,"abstract":"<p>The structural response under earthquake excitation can be simulated by shake table tests. However, the performance of the shake table is affected by the Control-Structure Interaction (CSI) effect. In recent years, nonlinear control algorithms were developed to compensate for the CSI effect. In this study, a model reference adaptive control algorithm, named model reference adaptive hierarchical control (MRAHC) framework, is presented. MRAHC consists of a high (adaptive) and low (loop-shaping) level controller. The high-level (adaptive) controller develops the control algorithm on the system level, which directedly considers the inherent nonlinearity of the test specimen and the CSI effect. While the low-level (loop-shaping) controller develops the control algorithm to regulate the hydraulic system and make sure it can follow the reference signal generated by the high-level (adaptive) controller. MRAHC offers many advantages including direct compensation to the structural nonlinearity and the ability to handle the CSI effect. In addition, it allows users to quantify the mass of the test specimens without measurement. To evaluate the performance of the MRAHC method, shake table tests with different upper structure masses were carried out. The performance of the MRAHC was compared with the direct loop-shaping control method (LC) and the Proportional-Integral-Differentiation control method (PID). The results show that the MRAHC can achieve better acceleration tracking compared to the LC and PID control methods. Hence, the MRAHC can be used as an effective nonlinear controller for shake table tests.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"346-362"},"PeriodicalIF":4.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4256","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142861975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Seismic design of steel moment-resisting knee-braced frame system by failure mode control","authors":"Mostafa Fathi Sepahvand, Akhrawat Lenwari","doi":"10.1002/eqe.4258","DOIUrl":"https://doi.org/10.1002/eqe.4258","url":null,"abstract":"<p>This paper presents the seismic design of a steel moment-resisting knee-braced frame (MKF) using the theory of plastic mechanism control (TPMC) within the capacity-based design framework. The MKF is an alternative system to MRFs, wherein knee elements are utilized to provide rigid connections and enhance lateral stiffness. Capacity-based design, the predominant approach in current seismic provisions, relies on two key principles: (1) selecting specific structural components as fuses with sufficient ductility to dissipate seismic energy, and (2) ensuring non-fuse elements can resist the maximum probable reactions from these fuses. The ultimate goal is to achieve a global mechanism where yielding occurs in all structural fuses and at the base of first-story columns. However, existing seismic design provisions often struggle to fully satisfy the second principle due to the lack of a method for controlling failure modes. TPMC addresses this challenge by ensuring compliance with the second principle, grounding its approach in the kinematic method and the mechanism equilibrium curve within the rigid-plastic analysis framework. By considering all potential story-based undesirable mechanisms and calculating the required plastic moment of columns up to a target design displacement, TPMC ensures adherence to the second principle of the capacity-based design approach, leading to the achievement of a global collapse mechanism. In this paper, an iterative method is proposed for designing beams and knee elements by considering plastic hinges at both ends of the beams, followed by a TPMC-based methodology for designing columns to ensure a global mechanism. A parametric analysis of a single-story single-span MKF explores the effects of knee element geometry (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>l</mi>\u0000 <mi>b</mi>\u0000 </msub>\u0000 <mo>/</mo>\u0000 <mi>L</mi>\u0000 </mrow>\u0000 <annotation>${l}_b/L$</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <mi>β</mi>\u0000 <annotation>$beta $</annotation>\u0000 </semantics></math>) on component demands. The results indicate that optimal parameter ranges of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>0.175</mn>\u0000 <mo>≤</mo>\u0000 <msub>\u0000 <mi>l</mi>\u0000 <mi>b</mi>\u0000 </msub>\u0000 <mo>/</mo>\u0000 <mi>L</mi>\u0000 <mo>≤</mo>\u0000 <mn>0.25</mn>\u0000 </mrow>\u0000 <annotation>$0.175 le {l}_b/L le 0.25$</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>40</mn>\u0000 <mo>∘</mo>\u0000 ","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"271-294"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Target-drift seismic-force-based design of one-story reinforced concrete precast buildings considering the requirements of the second generation of the Eurocode 8 standard","authors":"Tatjana Isaković","doi":"10.1002/eqe.4260","DOIUrl":"https://doi.org/10.1002/eqe.4260","url":null,"abstract":"<p>Results are presented concerning the force-based design of a wide range of reinforced concrete, single-story precast buildings, considering the requirements of the new Eurocode 8 standard. The relevant criterion defining the cross-sectional dimensions of the columns was the 2% drift limitation. Buildings were designed considering a behavior factor of 3 and a 50% reduction in stiffness corresponding to the gross cross-section. The design evaluation, using a nonlinear pushover analysis, revealed that all the buildings could expect approximately twice the drift considered in the design with significant second-order effects, particularly in very tall columns. The main reasons for large discrepancies between the elastic and nonlinear analyses were the arbitrarily selected behavior factor and the arbitrarily selected reduction in stiffness corresponding to the gross cross-section (the stiffness considered in the design was approximately double what the nonlinear analysis revealed). The analysis revealed that these two quantities are closely correlated. Once the dimensions of the columns had been selected, the force and initial stiffness reduction could not be chosen arbitrarily. Correlations were determined between the column dimensions, theoretical stiffness reduction, seismic force reduction (behavior factor) and second-order effects. From these correlations, a new target-drift force-based design methodology was proposed. All considered buildings were redesigned using the proposed method. The results of the new design and the nonlinear-pushover-based analysis correlated well.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"319-345"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4260","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Influence of masonry infills on seismic performance of BRB-retrofitted low-ductile RC frames","authors":"Rifan Chelapramkandy, Jayadipta Ghosh, Fabio Freddi","doi":"10.1002/eqe.4255","DOIUrl":"https://doi.org/10.1002/eqe.4255","url":null,"abstract":"<p>Reinforced concrete (RC) frames with masonry infills represent a prevalent construction typology across the globe, including moderate to high seismic regions. Such structures are often characterized by high seismic vulnerability, and consequently, there is an urgent need for retrofit solutions to effectively improve their seismic performance. Buckling-restrained braces (BRBs) represent one such solution. They are a type of dissipative device that can be included within the frames of an existing structure to increase its strength, stiffness, and energy dissipation capacity. Although a substantial amount of research has already been performed to understand the effectiveness of BRBs as a retrofit strategy, these studies have often neglected the contribution of masonry infills and the interactions between the infills and the BRBs. While masonry infills are usually overlooked in the analysis and design stage (owing to their brittle nature), past studies indicated that their strength and stiffness may significantly alter the structure's seismic performance, leading to undesirable and unexpected results. This study presents a detailed investigation of the impact of masonry infills on the seismic response and fragility of BRB-retrofitted RC frames. A three-story, three-bay, low-ductile RC frame has been selected for case study purposes. High-fidelity finite element models are developed in OpenSees for combinations of infilled and non-infilled structures—with and without BRBs. Nonlinear static and dynamic analyses are performed to evaluate the seismic response of the different configurations at local and global levels. Successively, cloud analyses are conducted by considering a set of 150 ground motion records to account for the record-to-record variability and develop seismic fragility curves. The present study sheds some light on the mutual interaction between the infill panels and BRBs retrofit intervention and highlights the critical aspects that must be considered in the design.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"295-318"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sensitivity of seismic fragility curves to multiple parameters using CyberShake simulated ground motions","authors":"Houssam Al Jamal, Sarah Azar, Mayssa Dabaghi","doi":"10.1002/eqe.4253","DOIUrl":"https://doi.org/10.1002/eqe.4253","url":null,"abstract":"<p>Several alternatives exist to compute seismic fragility curves. This study takes advantage of the large pool of site-specific CyberShake simulated ground motions (GMs) to investigate the sensitivity of fragility curves to multiple analysis parameters: the analysis method (Multiple Stripe Analysis (MSA), Cloud Analysis (CA), or Incremental Dynamic Analysis), the number and intensity measure distribution of the GMs used, the GM selection method, and the amount of scaling. To this end, the fragility curve of a two-dimensional steel frame is calculated for every analysis variation at the life safety limit state. By varying one parameter at a time, we can separate the effects of the various parameters from one another. We also assess the effect of the analysis parameters on the mean annual rate of exceedance of life safety. We find that if GMs are selected adequately for each method, different analysis methods can lead to consistent mean annual rates of exceedance despite some differences in their fragility curves. Generally, MSA and the proposed CA that models the increase of response variability with ground motion intensity best match empirical fragility points. The number of GMs affects the results for all analysis methods, while the intensity distribution of GMs affects results differently in different methods. When GMs are required to match earthquake scenario parameters in addition to intensity, more conservative fragility curves are obtained. Finally, fragility curves are sensitive to excessive scaling. This study provides important insights for performance-based earthquake engineering.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"246-270"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Seismic analysis of bridge with buckling-restrained brace posttensioned concrete pier","authors":"Anurag Upadhyay, Chris P. Pantelides","doi":"10.1002/eqe.4257","DOIUrl":"https://doi.org/10.1002/eqe.4257","url":null,"abstract":"<p>A two-span bridge built with a two-column pier consisting of unbonded posttensioned precast concrete columns and a buckling-restrained brace (BRB) is analyzed using a three-dimensional nonlinear numerical model. Seismic damage to the pier is eliminated through rocking of the posttensioned columns and seismic energy dissipation by the BRB. The numerical model is calibrated with experimental results of posttensioned columns and BRB structural elements. Seismic assessment of the bridge pier is performed using the ratio of BRB axial force to base shear as the parameter of interest. Limits for the seismic performance of the bridge pier are established by means of nonlinear static analysis using OpenSees. Bidirectional ground motions are used to perform probabilistic hazard analysis through nonlinear time history simulations. Three damage limit states are defined in this research: the activation point of posttensioning bars, the maximum base shear capacity or onset of concrete spalling, and collapse defined as the state at 20% loss of maximum base shear capacity. The analysis results are formulated into fragility curves for the three damage states as well as the residual drift. The fragility curves could be used for preliminary seismic bridge design. The analysis shows that the BRB dissipates significant seismic energy and the posttensioned concrete columns reduce residual displacements so that the bridge pier can remain functional after severe earthquakes. The fragility approach for designing bridge piers constructed with posttensioned concrete columns and BRB elements is a significant improvement over conventional seismic bridge design and can contribute to functional recovery after severe earthquakes.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"227-245"},"PeriodicalIF":4.3,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4257","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142861947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient seismic fragility analysis considering uncertainties in structural systems and ground motions","authors":"Jungho Kim, Taeyong Kim","doi":"10.1002/eqe.4254","DOIUrl":"https://doi.org/10.1002/eqe.4254","url":null,"abstract":"<p>Fragility plays a pivotal role in performance-based earthquake engineering, which represents the seismic performance of structural systems. To comprehensively understand the structural performance under seismic events, it is necessary to consider uncertainties in the structural model, i.e., epistemic uncertainties. However, considering such uncertainties is challenging due to computational complexity, leading most fragility analyses only to consider the chaotic behavior of ground motions on structural responses, i.e., aleatoric uncertainties. To address this challenge, this study proposes an adaptive algorithm that intertwines with the conventional fragility analysis procedures to consider both aleatoric and epistemic uncertainties. The algorithm introduces Gaussian process-based metamodels to efficiently consider epistemic uncertainties with a small number of time history analyses. Steel moment-resisting frame structures and a reinforced concrete building are used to demonstrate the improved efficiency and wide applicability of the proposed method. In each case, the proposed method yields fragility curves consistent with reference solutions but with substantially lower computational effort. Comprehensive discussions are provided regarding ground motion sets, structural types, and definitions of limit-states to demonstrate the robustness of the proposed approach.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"206-226"},"PeriodicalIF":4.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4254","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142861380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The analytical curvature distribution model of columns and mathematical solution for pushover analysis","authors":"Jian Zhong, Yanyan Zhu, Hao Wang","doi":"10.1002/eqe.4245","DOIUrl":"https://doi.org/10.1002/eqe.4245","url":null,"abstract":"<p>The acquisition of a flexural backbone curve for columns primarily relies on finite element analysis and experiments, of which the complexity and high cost are significant challenges. Hence, this study proposes an analytical curvature distribution model (CDM) along the full height of the column, which is the key point of formula derivation and theoretical solution of the column backbone curve. The proposed CDM is a piecewise function model composed of linear and quadratic functions, with the characteristics of continuity and differentiability at the intersection point. The deformation compatibility equations, equilibrium equations, and material constitutive equations based on the variables of CDM are constructed to form an equation system, the solution of which can be theoretically determined by an iterative algorithm. Furthermore, 155 test specimen columns of different materials, for example, reinforced concrete, high-strength reinforced concrete, and shape memory alloy are used to validate the proposed CDM and mathematical solutions of pushover analysis through three crucial indicators, that is, goodness of fit of backbone curve, ultimate displacement, and peak force, indicating strong practicability, high accuracy, and wider applicability. This theoretical method can be applied to deal with the key issues of interest during pushover analysis, that is, predicting the flexural backbone curves with different materials, determining the curvature distribution throughout the entire process of pushover analysis, and characterizing the evolution process of the plastic region.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"182-205"},"PeriodicalIF":4.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142861382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yingri Cao, Peng Pan, Zhizhou He, Jiangbo Sun, Jiangtao Wen, Gang Mao
{"title":"In situ tests of building structures isolated by innovative three-dimensional vibration isolation bearings","authors":"Yingri Cao, Peng Pan, Zhizhou He, Jiangbo Sun, Jiangtao Wen, Gang Mao","doi":"10.1002/eqe.4250","DOIUrl":"https://doi.org/10.1002/eqe.4250","url":null,"abstract":"<p>An innovative three-dimensional vibration isolation bearing (3D-VIB) was proposed in past studies to mitigate rail-induced vibration and improve the seismic performance of buildings. The 3D-VIB was composed of a thick laminated rubber bearing as the vertical vibration isolation element and a friction pendulum system as the horizontal seismic isolation element. In this study, in situ tests were carried out on a subway over-track structure with 3D-VIBs. The in situ tests included the subway-induced vibration excitation test and the horizontal loading test on the same structure. In the subway-induced vibration excitation test, the vertical isolation performance of the test structure was changed by transforming the isolation layer from a normal vibration-isolation-state to a non-isolation-state. The comparison between the two states proved that the installation of 3D-VIBs significantly changed the vertical vibration mode and reduced the subway-induced vibration of the superstructure. The shear performances of the isolated structure were examined by the horizontal loading test, which subjected the superstructure to a large horizontal movement under external load. The shear performances of the structure with 3D-VIBs were consistent with that of the 3D-VIB specimens measured in the laboratory. The in situ tests confirmed the effectiveness and stability of the 3D-VIBs when applied to practical engineering.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 1","pages":"146-163"},"PeriodicalIF":4.3,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142860938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}