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The behavior of steel plate shear walls under the effects of lateral loads depends on the stiffness of the surrounding frame members. Previous research has quantified the minimum required stiffness of columns in the middle stories of steel plate shear wall systems. As the columns of the steel plate shear wall system are subjected to both large axial forces and bending moments, use of composite columns is a viable option in this system. Among the different types of composite columns, the recently developed partially encased composite columns with built-up steel sections have some advantages over other types of composite columns and thus their performance as columns in steel plate shear wall systems needs to be studied. In the first part of this research, a numerical and analytical study has developed a new design parameter and determined the minimum required stiffness of end beams in end panels of the steel plate shear wall system. The effect of the rigidity of the frame connections on the uniformity of the tension field has also been studied in this part. The second part of this research includes two large scale tests on steel plate shear walls with built-up partially encased composite (PEC) columns. One of the test specimens was modular and the other one used reduced beam sections in the frame. The results of the tests show that the columns were stiff enough to anchor the infill plate. The PEC columns in these tests performed in a ductile manner. The overall system behavior was ductile, stable and the specimens showed good seismic behavior and redundancy. Based on the results and observations of this research, design recommendations for PEC columns used as the vertical boundary members of steel plate shear walls are provided. / Structural Engineering

Finite element method and strip method are two widely used techniques for analyzing steel plate shear wall (SPSW) systems. Past research mostly focused on the prediction of lateral load capacity of these systems using these numerical methods. Apart from the lateral load carrying capacity, the lateral stiffness of the wall system needs to be determined for a satisfactory design. Lateral displacements and the fundamental natural frequency of the SPSW system are directly influenced by the lateral stiffness. In this study the accuracy of the finite element method and strip method of analysis are assessed by making comparisons with experimental findings. Comparisons revealed that both methods provide in general solutions with acceptable accuracy. While both methods offer acceptable solutions sophisticated computer models need to be generated. In this study two alternative methods are developed. The first one is an approximate hand method based on the deep beam theory. The classical deep beam theory is modified in the light of parametric studies performed on restrained thin plates under pure shear and pure bending. The second one is a computer method based on truss analogy. Stiffness predictions using the two alternative methods are found to compare well with the experimental findings. In addition, lateral stiffness predictions of the alternate methods are compared against the solutions provided using finite element and strip method of analysis for a class of test structures. These comparisons revealed that the developed methods provide estimates with acceptable accuracy and are simpler than the traditional analysis techniques.

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Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15723号 / 工博第3337号 / 新制||工||1504(附属図書館) / 28268 / 京都大学大学院工学研究科建築学専攻 / (主査)教授 中島 正愛, 教授 吹田 啓一郎, 教授 金子 佳生 / 学位規則第4条第1項該当

A new type of steel plate shear wall has been devised which resists out-of-plane buckling without requiring stiffeners. The ring-shaped steel plate shear wall (RS-SPSW) includes a web plate that is cut with a pattern of holes leaving ring-shaped portions of steel connected by diagonal links. The ring shape resists out-of-plane buckling through the mechanics of how a circular ring deforms into an ellipse. It has been shown that the ring's compression diagonal will shorten a similar amount as the tension diagonal elongates, essentially eliminating the slack in the direction perpendicular to the tension field. Because of the unique features of the ring's mode of distortion, the load-deformation response of the resulting RS-SPSW system can exhibit full hysteretic behavior and possess greatly improved stiffness relative to thin unstiffened SPSW. The concept has been validated through testing on seven 34 in x 34 in panels. General conclusions about influence of different geometric parameters on plate behavior have been made. / Master of Science

Steel plate shear walls (SPSWs) are an attractive option for lateral load resisting systems for both new and retrofit construction. They, however, present various challenges that can result in very thin web plates and excessively large boundary elements with moment connections, neither of which is economically desirable. Moreover, SPSW also suffers from buckling at small loads which results in highly pinched hysteretic behavior, low stiffness, and limited energy dissipation. To mitigate these shortcomings, a new type of SPSW has been developed and investigated. The buckling resistant steel plate shear wall (BR-SPSW) utilizes a unique pattern of cut-outs to reduce buckling. Also, it allows the use of simple shear beam-column connections and lends tunability to the shear wall system. A brief discussion of the concept behind the BR-SPSW is presented. A detailed parametric study is presented that investigates the sensitivity of the local and global system behavior to the geometric design variables using finite element models as the main tool. The key output parameters which define the system response are discussed in detail. Analytical solutions for some output parameters like strength and stiffness have been derived and resulting equations are proposed. Finally, preliminary suggestions have been made about how this system can be implemented in practice to improve the seismic resistance of the buildings. The proposed BR-SPSW system was found to exhibit relatively fuller hysteretic behavior with high resistance during the load reversals, without the use of moment connections. / Master of Science

A novel shear wall system for building structures has been developed that improves upon the performance of conventional steel plate shear walls by mitigating buckling. The new structural system, called the Ring Shaped - Steel Plate Shear Wall, was investigated and developed through experimental and computational methods. First, the plastic mechanism of the system was numerically derived and then analytically validated with finite element analyses. Next, five large-scale, quasi-static, cyclic experimental tests were conducted in the Thomas M. Murray Structures Laboratory at Virginia Tech. The large-scale experiments validated the system performance and provided data on the boundary frame forces, infill panel shear deformation modes, buckling mode shapes, and buckling magnitudes. Multiple computational modeling techniques were employed to reproduce different facets of the system behavior. First, detailed finite element models were constructed to accurately reproduce the cyclic performance, yielding pattern, and buckling mode shapes. The refined finite element models were utilized to further study the boundary element forces and ultra-low cycle fatigue behavior of the system. Second, reduced-order computational models were constructed that can accurately reproduce the hysteretic performance of the web plates. The reduced-order models were then utilized to study the nonlinear response history behavior of four prototype building structures using Ring Shaped - Steel Plate Shear Walls and conventional steel plate shear walls. The nonlinear response history analyses investigated the application of the system to a short period and a long period building configuration. In total 176 nonlinear response history analyses were conducted and statistically analyzed. Lastly, a practical design methodology for the Ring Shaped - Steel Plate Shear Wall web plates was presented. The experimental tests and computational simulations reported in this dissertation demonstrate that Ring Shaped - Steel Plate Shear Walls are capable of improving seismic performance of buildings by drastically reducing buckling and improving cyclic energy dissipation. / Ph. D. / A novel shear wall system for building structures has been developed that improves the performance of of buildings subjected to seismic loads. The new structural system, called the Ring Shaped - Steel Plate Shear Wall, was investigated and developed through experimental and computational methods. Five large-scale, cyclic experimental tests were conducted in the Thomas M. Murray Structures Laboratory at Virginia Tech. The large-scale experiments validated the system performance and provided data on the design forces and modes of failure. Multiple modeling techniques were employed to reproduce different facets of the system behavior. Refined finite element models were utilized to further study the system forces and failure modes. Other computational models were constructed to accurately reproduce the cyclic performance of the system. These models were then utilized to study the seismic behavior of four prototype building structures using the Ring Shaped - Steel Plate Shear Walls and conventional steel shear walls. Lastly, a practical design methodology for the Ring Shaped - Steel Plate Shear Wall web plates was presented. The experimental tests and computational simulations reported in this dissertation demonstrate that Ring Shaped - Steel Plate Shear Walls are capable of improving seismic performance of buildings. Additionally, the presented design methodology allows designers and researchers to continue exploring the RS-SPSW system.

Design recommendations for steel plate shear wall (SPSW) systems have recently been introduced into seismic provisions for steel buildings. Response modification, overstrength, and displacement amplification factors for SPSW systems presented in the design codes were based on professional experience and judgment. A numerical study has been undertaken to evaluate these factors for SPSW systems. Forty four unstiffened SPSWs possessing different geometrical characteristics were designed based on the recommendations given in the AISC Seismic Provisions. Bay width, number of stories, story mass, and steel plate thickness were considered as the prime variables that influence the response. Twenty records were selected to include the variability in ground motion characteristics. In order to provide a detailed analysis of the post-buckling response, three-dimensional finite element analyses were conducted for the 44 structures subjected to the selected suite of earthquake records. For each structure and earthquake record two analyses were conducted in which the first one includes geometrical nonlinearities and the other one includes both geometrical and material nonlinearities, resulting in a total of 1760 time history analysis. In this thesis, the details of the design and analysis methodology are given. Based on the analysis results response modification, overstrength and displacement amplification factors for SPSW systems are evaluated.

Steel plate shear walls (SPSWs) are a lateral force resisting system consisting of thin infill steel plates surrounded by boundary frame members. The infill steel plates are allowed to buckle in shear and subsequently form diagonal tension field actions during earthquake events. Hysteretic energy dissipation of this system is primarily achieved through yielding of the infill plates. Conceptually, in a SPSW system with ideally rigid columns pinned to ground, the infill plates at different stories will yield simultaneously as a result of the lateral loads. However, when the columns become flexible, infill plate yielding may initially occur at one story and progressively spread into the other stories with increasing roof displacement. This research investigates the effect of column stiffness on infill plate yielding sequence and distribution along the height of steel plate shear walls subjected to earthquake forces. Analytical models are derived and validated for two-story SPSWs. Based on the derived model, probabilistic simulations are conducted to calculate the probability of achieving infill plate yielding in both stories before occurrence of a premature failure caused by excessive inter story drift at the initially yielded story. A total of three simulation methods including the Monte-Carlo method, the Latin Hypercube sampling method, and the Rosenblueth’s 2K+1 point estimate method were considered to account for the uncertain infill plate thickness and lateral force distributions in the system.The investigation is also extended to multi-story SPSWs. Three example six-story SPSWs are evaluated using the Rosenblueth's 2K+1 point estimation method which is identified to be most efficient from the simulation on two-story SPSWs. Moreover, the effectiveness of the column minimum moment of inertia required in the current code for achieving infill plate yielding at every story of SPSWs is evaluated.