Study On Internal Force Distribution Of RC Shear Wall Structure Under Earthquake Loading

Shear wall structure is easy to meet the architectural space layout, and the larger lateral stiffness ratio of shear wall structure can make up the defect-the larger lateral deformation for higher frame structure. So shear wall structure has been accepted by China’s construction market. It has been widely used in high-rise residential building in large and medium cities at present. But there are still some problems for the seismic design of shear wall structure. For architectural functional requirements in engineering practice, the opening size of shear wall is different, which causes the different deformation for different shall wall types. As the frame-shear wall structure, the combined of different shear wall types will produce unpredictable dynamic response under the earthquake. Therefore, it is a necessity to study on the internal force distribution of the shear wall structure.This paper has studied the loading characteristic for different types of shear wall through static analysis and established pseudo three-dimensional shear wall structures for different forms and stiffness ratio of shear wall. It has summarized the regularity of internal force distribution of different shear wall types. Two typical shear wall structure whose stiffness ratio is 3 are also designed. Nonlinear time history analysis is applied for the two typical shear wall structures to verify the regularity of internal force distribution and the pseudo three-dimensional model.The main conclusions are acquired by comparison as follows:(1) The precision of MPA method is higher than than the other lateral loading pattern; For shear wall structure with 15 floors, MPA analysis with third-order combination can get higher accuracy results of elastic-plastic prediction, for the structure with higher floors, the error of MPA analysis with third-order combination is larger.(2) The effect of changing the height of the connecting beam on beam shear is not significant. The section bearing capacity may decline faster, it is difficult to solve the problem of overload ratio of beam shear pressure. When the section height adjustment of shear wall limb is limited, increasing the beam span is a effective method to solve the problem of overload ratio of beam shear pressure.(3) The integral shear wall and small openings shear wall can be classified in one type because the same mechanical and deformation characteristics. For other forms, their deformation and mechanical characteristics have significant difference. With the wall limb and coupling beam more weaken, there is a transition from shear wall to frame. Thus, in the shear wall structure, if two or more forms of shear wall are present at the same time, internal force redistribution will be generated for shear wall under seismic action.(4) The location of max horizontal force the floor appears at the bottom and the roof, so when the stiffness and deformation characteristics of the high-rising structure are quite different, the panel stiffness of the bottom and roof floor needs to be appropriately increased.(5) The damage of wall limb and coupling beam has a close relation to internal force distribution under the frequent earthquakes, medium earthquake, rare earthquake, and super large earthquake. Although with different types of shear wall together, the damage of wall limb has the similar extent and internal force redistribution is not obvious when the wall limb stiffness ratio is relatively small. Especially for structure with small openings and coupled shear wall, regardless of the stiffness ratio, there is no significant internal force redistribution.(6) When the stiffness ratio of wall limb is no less than 2, the small opening wallframe structure and coupled shear wall-frame-wall structure will have a significant internal force redistribution under rare earthquake. So seismic shear force of weak wall limb should be made some adjustments under frequent earthquake as the frame-shear wall structure and the effect that internal force redistribution should be paid more attention, seismic shear force of weak wall limb should be not less than the total base shear by the lateral stiffness ratio in the design of shear walls. When considering the internal force distribution, the structure can be more secure. In addition, the case that the wall was damaged one by one will not appear under the earthquake and the weak shear wall could act as a second line of defense.Innovations of the paper are as follows: studying on the deformation and mechanical characteristics of different types of shear wall; studying on the problem of floor should be considered in the design of high-rise structure; studying on the characteristics of the deformation and internal force distribution in the structure with different forms of shear wall, and the adjustment of the internal force in the design.