| Steel frames with multi-ribbed grid composited steel plate shear walls(SMRG-SPSW), which consist of steel frame members, the infill plates and the multi-ribbed grid, are a effective and economical lateral load resisting system, with beneficial properties for seismic applications, such as high ductility, robust resistance to cyclic degradation and resilient redundancy. When subject to lateral loading in the plane of the wall, forces are resisted through the flexural and coupled axial response of the columns and beams and by in-plane shear resistance of the infill panels, anchored between the frame members. The resistance of the slender unstiffened SPSW consists of post-buckling strength alone, attained by the development of a tension field within the plates, which will suffer out-of-plane buckling in normal state. The sizing of vertical and horizontal boundary elements makes it possible to develop this tension field action across the webs. Based on the work mechanism and deformation characteristics of slender unstiffened steel plate shear walls, set the milti-ribbed grids on the both sides of the shear walls to put the panels off out-of-plane buckling, limit the deformation of the panels, ameliorate the seismic performance, reduce the requirement of the flexure stiffness, and improve the lateral stiffness and the energy dissipation capacity of the structure. It has formed a new type of multi-ribbed grid composite steel plate shear walls.This dissertation reports on a research program conducted on investigate the seismic behavior of the SMRG-SPSW, which through the theoretical analysis, experimental study and finite element calculation. Analyze the hysteretic behavior of SMRG-SPSW subjected to a quasi-static, fully reversed, cyclic load, and investigate the work mechanism and the failure model of the structure, and give the required flexural rigidity of the ribs, and propose the performance-based plastic design method(PBPD) for the slender steel plate shear walls(SPSW), and provide the basis for the application and promotion of the SMRG-SPSW. The main research contents are listed as follows:(1) To examine the seismic behavior of the SPSW, three large scale single bay and two storys specimens and a large scale two bays and two storys specimen of the semi-rigid steel frames with multi-ribbed grid composited steel plate shear walls were tested under the low frequency cyclic loading to failure. By analyzing the lateral bearing capacity, stiffness, ductility, energy dissipation capacity, shear distribution, failure model and the performance of frames cooperating with shear walls, the force-transferring and energy dissipation mechanism for the structure were achieved, and provide basis for the subsequent analysis.(2) The static nonlinear analysis(Pushover analysis) was conducted for the test specimens using the finite element software SAP2000 with the strip model and the three strip model. It is verified that the simple models are effective and applicable by comparison of the stiffness, strength, plastic development, deformation capacity and the failure model of the specimens between the test results and the finite element model results. The research provides a basis for the following investigation.(3) Based on the theory of elastic stability, the overall stiffness of the multi-ribbed grid plate which consists of a large number of parallel, equal and equidistant vertical and horizontal ribs, maximum spacing between the adjacent ribs, the size and maximum pitch of the high strength bolts fixing the multi-ribbed grid were investigate systematically by the theoretical analysis combined with the calculation of the 3D finite element model. The formulae for determining the minimum stiffness of the ribs, the maximum spacing between the ribs as well as the maximum pith of the connecting bolts are proposed.(4) Based on the energy balance concept, a performance-based plastic design method(PBPD) for the slender steel plate shear walls(SPSW) is proposed in the work, and require that seismic-induced shears and overturning moments calculated at each story level be amplified to account for the P-delta effect. This method directly accounts for the inelastic behavior of SPSW by using pre-selected target drift and yield mechanism as key performance limit states. The design base shear for a specified hazard level is derived based on the inelastic state of the SPSW, with the drift control built-in, by equating the work needed to push the structure monotonically up to the target drift to energy requited by an equivalent elastoplastic-single degree of freedom(EP-SDOF) system to achieve the same state. Plastic design is then performed to detail the steel plate shear walls in order to achieve the intended yield mechanism and behavior. The design of members that are intended to remain elastic, such as columns and beams in a SPSW is performed based on capacity design approach. The effectiveness of the proposed method is illustrated through sample case study of a ten-storey SPSW building, and validated by pushover analysis and dynamic elastic-plastic analysis. The addressed method herein can form a basis for the performance-based plastic design for SPSW systems. |
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