Elastoplastic Analysis Of Short-Leg Shear Wall Under Seismic

Short-leg shear wall structure is a new type of structure system, which has the advantages both of frame and shear wall. In recent years, this structure system has been extensively applied in our country. But the theory and experiment on this structure are behind of its application, and the mechanic models and calculation methods of the structural system are short of relatively detailed research on the analytical theory, especially in elastoplastic time-history analysis. This paper mainly analyzes the short-leg shear wall's aseismic performance.The improved Muti-Vertical-Line-Element-Model is adopted as the basic element for the elastoplatic analysis, and the problem of the shear-lag effect is considered. Partial Muti-Vertical-Line-Element-Model with rigid region is used to analyze the beams. Then the elastoplatic analysis stiffness matrixs of short-leg shear wall and coupling beam are derived by the principle of minimum potential energy and variational principle; the correlative coefficient of the ratio of bending moment to shearing force is used to modify the stiffness matrix; it is more close to the structure behavior. Restoring force model of Vertical-Line in elastoplastic time-history analysis is studied.Finally, two microcomputer-based programs are developed by MATLAB, one of which is for short-leg shear wall element and the other is for the monolithic structure. Then, two examples are calculated by using the programs by inputting three kinds of earthquake waves, including elastic analysis under small seismic and plastic analysis under violent seismic. The element is analyzed with different parameters, such as the ratio of length to thickness of the wall, the ratio of height to span of the coupling beam, the ratio of reinforcement in coupling beam and so on. The influences of these parameters are studied. And the lateral displacement curve of the monolithic structure is also studied: (1) the lateral displacement of the monolithic structure is flexure-shearing type deformation under small seismic; (2) the ground floor's displacement is the biggest under violent seismic, so more attention should be paid to the ground floor in the designing.