{"title":"Full-Scale Beam-To-Column Subassemblage Testing for Seismic Evaluation of Deep Columns","authors":"Claudio Sepulveda, Gulen Ozkula, Gilberto Mosqueda, Chia-Ming Uang, Chung-Che Chou, Kung-Juin Wang, Sherif El-Tawil, Jason McCormick","doi":"10.1002/eqe.4309","DOIUrl":"https://doi.org/10.1002/eqe.4309","url":null,"abstract":"<p>Steel moment frames composed of wide-flange steel members are commonly used in seismic regions, with deep and slender column sections often selected to economically satisfy drift limit requirements. The section slenderness makes the columns more susceptible to local and global buckling and subsequent axial shortening when subjected to combined high axial forces and lateral deformations. Numerous tests have been conducted on individual column members under a wide range of axial loads and loading patterns. Experimental data of subassembly or complete frame configurations providing insight into system level interaction of the column with the frame are more limited. To address this concern, a full-scale testing program was conducted on four cruciform beam-to-column subassemblage subjected to loading patterns based on cyclic quasi-static and slow hybrid simulation. Quasi-static tests followed standard AISC loading protocol with constant column axial load ranging from 20% to 40% of the yield capacity. Advanced hybrid simulations subjected the specimens to realistic earthquake loading patterns to levels consistent with design basis earthquake (DBE) and maximum considered earthquake (MCE) ground motions. A full nonlinear model of a complete 6-story frame was developed for the numerical substructure in the hybrid simulation. The observed local and global responses of two quasi-static and two hybrid tests are presented, providing valuable data towards improving the understanding of progress of damage for these systems through advanced testing techniques.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 4","pages":"1289-1310"},"PeriodicalIF":4.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530380","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":"Dynamic Analysis of a Periodic Soil-Structure Interaction System to Reduce Ground Vibration","authors":"Dinh-Tuan Nguyen, Jin Ho Lee","doi":"10.1002/eqe.4310","DOIUrl":"https://doi.org/10.1002/eqe.4310","url":null,"abstract":"<div>\u0000 \u0000 <p>Metamaterials have been developed to control electromagnetic, acoustic, and elastic waves, and can also be employed to manage seismic waves. As building clusters can significantly affect ground vibrations, this study extends the concept of metamaterials to evaluate a periodic soil-structure interaction (SSI) system capable of reducing the ground vibrations caused by seismic waves. Using the theory of SSI with Floquet–Bloch theorem, a governing equation for a unit cell in a periodic SSI system is derived with effective earthquake forces from exterior sources. The dispersion relations of the periodic SSI system are subsequently obtained, and its frequency band gaps (FBGs) for surface waves are identified. Furthermore, the dynamic stiffness of rigid foundation, on which periodic superstructures are installed, and corresponding input motion are calculated when Rayleigh surface waves are incident to the system. The results indicated that foundation input motion is significantly reduced resulting in a reduction of structural response, and the dynamic displacements of the soil surface are significantly reduced owing to the FBGs within the SSI system. Finally, a parametric study is conducted to examine the effects of clear spacing between buildings, building height, and shear wave velocity in the underlying half-space on SSI system behavior. The results confirm that the dynamic characteristics of a periodic SSI system depend on these factors and it must be designed accordingly.</p>\u0000 </div>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 4","pages":"1270-1288"},"PeriodicalIF":4.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530378","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}
Pedram Mortazavi, Oh-Sung Kwon, Constantin Christopoulos
{"title":"Challenges and Lessons Learned From Pseudo-Dynamic Hybrid Simulations on Ductile Steel Braced Frame Systems","authors":"Pedram Mortazavi, Oh-Sung Kwon, Constantin Christopoulos","doi":"10.1002/eqe.4301","DOIUrl":"https://doi.org/10.1002/eqe.4301","url":null,"abstract":"<p>Performance-based seismic design, which emerged more than two decades ago, requires accurate numerical models to capture the response of structural elements that undergo inelastic deformations under random loading histories. High-fidelity benchmark test results under real natural hazards are therefore required to assist researchers and practitioners with this effort. Substructuring pseudo-dynamic hybrid simulation (PsDHS) is an efficient, yet effective testing method for evaluating the system-level response of structures under extreme loading scenarios, and for forming a database of high-fidelity benchmark test results. In PsDHS, the response of the critical structural components is captured in a laboratory through physical testing and is integrated with the numerical response of the remainder of the structure in a numerical model, by establishing a communication framework between the two. The former is referred to as a physical substructure and the latter is often referred to as the integration module. Despite its efficiency and effectiveness, large-scale hybrid simulation introduces researchers to a range of non-trivial challenges, especially in laboratories that are new to the methodology. This paper presents challenges and lessons learned from 21 large-scale pseudo-dynamic hybrid simulations on different ductile steel braced frame systems including a buckling-restrained braced frame (BRBF), a special concentrically braced frame (SCBF), a yielding brace system (YBS) equipped with cast steel yielding connectors (YCs), and eccentrically braced frames (EBFs) designed with cast steel replaceable modular yielding links (CMLs). Details for each hybrid simulation including the experimental setups, reference buildings, earthquake records, etc. along with selected results are presented. Challenges that were faced in each hybrid simulation related to hardware, the control system, integration schemes, etc., and attempted solutions are discussed. The findings from each set of hybrid simulations on each braced frame system are summarized. The experimental results are organized as a dataset in an online data repository, which is available for download. The organization of the dataset is presented to facilitate access to the experimental results. In the end, concluding remarks and visions for future research are presented.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 4","pages":"1229-1250"},"PeriodicalIF":4.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4301","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530448","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":"Nonlinear Signal-Based Control for a Shake Table Supporting a Heavy Multi-Storey Nonlinear Structure","authors":"Ryuta Enokida, Kohju Ikago, Koichi Kajiwara","doi":"10.1002/eqe.4308","DOIUrl":"https://doi.org/10.1002/eqe.4308","url":null,"abstract":"<p>Shake table control is greatly affected by an interaction with a heavy specimen, especially when it has severe nonlinear characteristics. Hence, to this fundamental and challenging issue in the experimentation, this study proposes a solution using nonlinear signal-based control (NSBC) and demonstrates its effectiveness in actual experiments. Moreover, an innovative controller design is presented in this paper: the bare condition referenced (BCR) approach relies on the bare table dynamics and the specimen's weight. It frees the design from the properties of the controlled system, in contrast to the orthodox approach, which uses the dynamics of a table supporting a specimen. Following numerical examinations including a stability analysis, experiments were carried out on NSBC with these approaches, with a table having a three-storey structure that was 2.5 times heavier than the table and had nonlinear characteristics. An inversion-based controller, using a feedforward controller only, did not perform well, even at small excitations, owing to the modelling gap and nonlinearity. NSBC, with the orthodox approach, accurately realised the expected acceleration on the table, despite the considerable interaction with the specimen and the nonlinearity of its collapse level. NSBC, with the BCR approach, performed as well or better than the orthodox approach, despite the obvious modelling gap and nonlinearity. NSBC with both approaches can solve the challenging control problem and has considerable potential for deployment in large experiments. Furthermore, the BCR approach is more advantageous than the orthodox approach, as it eliminates the need to identify the dynamics of the table supporting the specimen.</p>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 4","pages":"1251-1269"},"PeriodicalIF":4.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/eqe.4308","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530449","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}
M. Amirmojahedi, A. Mojoodi, Saeed Shojaee, Saleh Hamzehei-Javaran
{"title":"Application of an Off-Policy Reinforcement Learning Algorithm for \u0000 \u0000 \u0000 H\u0000 ∞\u0000 \u0000 ${{H}_infty }$\u0000 Control Design of Nonlinear Structural Systems With Completely Unknown Dynamics","authors":"M. Amirmojahedi, A. Mojoodi, Saeed Shojaee, Saleh Hamzehei-Javaran","doi":"10.1002/eqe.4299","DOIUrl":"https://doi.org/10.1002/eqe.4299","url":null,"abstract":"<div>\u0000 \u0000 <p>This paper proposes a model-free and online off-policy algorithm based on reinforcement learning (RL) for vibration attenuation of earthquake-excited structures, through designing an optimal <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>H</mi>\u0000 <mi>∞</mi>\u0000 </msub>\u0000 <annotation>${{H}_infty }$</annotation>\u0000 </semantics></math> controller. This design relies on solving a two-player zero-sum game theory with a Hamilton–Jacobi–Isaacs (HJI) equation, which is extremely difficult, or often impossible, to be solved for the value function and the related optimal controller. The proposed strategy uses an actor-critic-disturbance structure to learn the solution of the HJI equation online and forward in time, without requiring any knowledge of the system dynamics. In addition, the control and disturbance policies and value function are approximated by the actor, the disturbance, and the critic neural networks (NNs), respectively.</p>\u0000 <p>Implementing the policy iteration technique, the NNs’ weights of the proposed model are calculated using the least square (LS) method in each iteration. In the present study, the convergence of the proposed algorithm is investigated through two distinct examples. Furthermore, the performance of this off-policy RL strategy is studied in reducing the response of a seismically excited nonlinear structure with an active mass damper (AMD) for two cases of state feedback. The simulation results prove the effectiveness of the proposed algorithm in application to civil engineering structures.</p>\u0000 </div>","PeriodicalId":11390,"journal":{"name":"Earthquake Engineering & Structural Dynamics","volume":"54 4","pages":"1210-1228"},"PeriodicalIF":4.3,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530786","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}