Patricia M. Clayton

Seismic Design and Performance of Self-Centering Steel Plate Shear Walls

The self-centering steel plate shear wall (SC-SPSW) is a new seismic load-resisting system that combines the strength and stiffness properties of the SPSW with the recentering capabilities of posttensioned (PT) beam-to-column connections. This paper outlines a proposed seismic design procedure aimed at achieving specified structural performance targets and analytical methods for modeling such a system. A series of 3-and 9-story prototype buildings located in a high seismic zone in California was designed using the procedure, and nonlinear, dynamic analyses were performed for these prototype buildings using ground motions representing three seismic hazard levels. The analysis results show that the systems achieved the desired performance objectives, including recentering of the lateral system.

Experimental Investigation of Self-Centering Steel Plate Shear Walls

AbstractA series of subassembly tests were conducted to investigate the behavior of the self-centering steel plate shear wall (SC-SPSW) system under cyclic loading. The SC-SPSW system utilizes thin steel web plates to provide energy dissipation and the primary strength and stiffness of the system, whereas posttensioned (PT) beam-to-column connections provide recentering capabilities. In this new system, the web plate is intended to yield under cyclic loading, whereas the boundary elements and PT connection elements remain undamaged. The web plate can then be replaced relatively easily following significant inelastic cycles. This experimental program studies the effects of various design parameters on the system and connection response and compares the response with approximate analytical formulas. The experimental results show that the SC-SPSW system has high ductility, high initial stiffness, recentering capabilities, an overall system response as anticipated, and more energy dissipation than expected.

Full-scale testing of self-centering steel plate shear walls

This paper presents the results of a self-centering steel plate shear wall (SC-SPSW) experimental program conducted at the National Center for Research on Earthquake Engineering (NCREE) as part of a collaborative research endeavor. Two full-scale two-story SC-SPSW specimens were tested under pseudo-dynamic loading. The specimens investigated two different post-tensioned (PT) beam-to-column connection configurations—one using a PT connection detail where a gap forms in a connection as the beam rocks about its flanges, and one using a PT connection (called the NewZBREAKSS connection) where the beam in a connection always rocks about its top flanges, thus eliminating the problem of frame expansion. The test specimens also incorporated a post-tensioned column base connection that allowed the column to rock about its flanges, relying on vertical post-tensioned rods anchored along the column height. The PT column base provides additional recentering capabilities, as well as eliminates the damage and residual plastic deformations that occur in the moment resisting base connections of SC-SPSWs. The results from this project will be used to validate numerical models and inform construction and design recommendations.

Seismic design and analysis of self-centering steel plate shear walls

An innovative Self-Centering Steel Plate Shear Wall (SC-SPSW) system is proposed. It relies on post-tensioned (PT) beam-to-column connections that allow beams to rock about their flanges and provide system re-centering capabilities. A design procedure for the SC-SPSW system, developed based on a performance based design (PBD) approach, is presented, followed by analytical results for a prototype SC-SPSW building designed using this PBD approach, and subjected to a suite of ground motions simulating three different seismic hazard levels. The results of the nonlinear response history analyses show the proposed SC-SPSW design procedure to adequately achieve the desired enhanced performance objectives. Concepts of capacity design principle are integrated in the above approach, to prevent in-span plastic hinges of the beam considering reduced moment capacity due to the presence of axial and shear forces and to ensure that PT reinforcement remain elastic, among other things. To facilitate understanding of the behavior and design of an SC-SPSW system, the moment, shear and axial force distribution along the length of a boundary beam are established based on first principles. Closed form formulations describing the moment, shear and axial force beam diagrams are developed based on component capacity design approach and are used in the performance-based system design approach.

Neural Network-Based Equations for Predicting PGA and PGV in Texas, Oklahoma, and Kansas.

Parts of Texas, Oklahoma, and Kansas have experienced increased rates of seismicity in recent years, providing new datasets of earthquake recordings to develop ground motion prediction models for this particular region of the Central and Eastern North America (CENA). This paper outlines a framework for using Artificial Neural Networks (ANNs) to develop attenuation models from the ground motion recordings in this region. While attenuation models exist for the CENA, concerns over the increased rate of seismicity in this region necessitate investigation of ground motions prediction models particular to these states. To do so, an ANN-based framework is proposed to predict peak ground acceleration (PGA) and peak ground velocity (PGV) given magnitude, earthquake source-to-site distance, and shear wave velocity. In this framework, approximately 4,500 ground motions with magnitude greater than 3.0 recorded in these three states (Texas, Oklahoma, and Kansas) since 2005 are considered. Results from this study suggest that existing ground motion prediction models developed for CENA do not accurately predict the ground motion intensity measures for earthquakes in this region, especially for those with low source-to-site distances or on very soft soil conditions. The proposed ANN models provide much more accurate prediction of the ground motion intensity measures at all distances and magnitudes. The proposed ANN models are also converted to relatively simple mathematical equations so that engineers can easily use them to predict the ground motion intensity measures for future events. Finally, through a sensitivity analysis, the contributions of the predictive parameters to the prediction of the considered intensity measures are investigated.

Advances in self-centering steel plate shear wall testing and design

The self-centering steel plate shear wall (SC-SPSW) was developed as part of a NEESR-SG research project aimed at leveraging the benefits of self-centering post-tensioned steel frames with the strength and ductility of steel plate shear walls. Initial proof-of-concept numerical simulations showed that the SC-SPSW was capable of providing enhanced seismic performance, including recentering under design-level earthquakes. This paper will present recent advances in experimental testing of the new lateral force-resisting system, as well as, design recommendations that followed from these experiments and supporting finite element analyses. The extensive test program consisted of three major components: (i) large-scale quasi-static testing of SC-SPSW subassemblies, (ii) quasi-static and shake table testing of third-scale, threestory SC-SPSWs, and (iii) pseudo-dynamic testing of two full-scale, two-story SC-SPSW at multiple seismic hazard levels. Major outcomes of these experimental and numerical studies include: validation of seismic performance of various SC-SPSW configurations, development of a new post-tensioned (PT) beam-to-column connection to eliminate frame expansion that is typical of self-centering systems, incorporation of PT column base connections into the SCSPSW performance-based seismic design procedure, and recommendations for SC-SPSW design, detailing, and modeling. The results of this research program can be used to inform designers and bring SC-SPSWs closer to implementation. 1 Assistant Professor, Dept. of Civil, Architectural & Environmental Engineering, University of Texas at Austin, Austin, TX 78712 2 Graduate Student Researcher, Dept. of Civil, Structural & Environmental Engineering, University at Buffalo, Buffalo, NY 14260 3 Assistant Research Fellow, National Center for Research on Earthquake Engineering, Taipei, Taiwan 4 Associate Professor, Dept. of Civil & Environmental Engineering, University of Washington, Seattle, WA 98195 5 Professor, Dept. of Civil, Structural & Environmental Engineering, University at Buffalo, Buffalo, NY 14260 6 Professor, Dept. of Civil Engineering, National Taiwan University, Taipei, Taiwan Clayton PM, Dowden DM, Li C-H, Berman JW, Bruneau M, Tsai K-C, Lowes LN. Advances in Self-Centering Steel Plate Shear Wall Testing and Design. Proceedings of the 10 National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Anchorage, AK, 2014. DOI: 10.4231/D3GM81P60 Advances in Self-Centering Steel Plate Shear Wall Testing and Design P. M. Clayton, D. M. Dowden, C.-H. Li, J. W. Berman, M. Bruneau, K.-C. Tsai, L. N. Lowes