Research On Seismic Performance And Performance Index Limits Of RC Shear Wall Components With Rectangular Section

As an important force-resisting component of the tall buildings, the deformation properties of the shear wall components have a greatly effect on seismic performance of the overall structure. The ductile demands of the components are ensured by corresponding structural measures and the quantitative criteria of the deformation properties for shear wall components are not given in current Chinese codes. Therefore the performance status of shear wall components under earthquakes cannot be evaluated properly. This paper mainly studies the seismic performance and the deformation performance index limits under frequent, fortified and severe earthquakes of RC shear wall components with rectangular section based on Chinese codes, including the following aspects:1) Nonlinear finite element method was used to simulate 27 isolated shear wall specimens and 2 coupled shear wall specimens, and their simulation results and experiments results of the specimens were compared and analyzed to verify the rationality and correctness of the finite element model and its parameters.2) Reliable nonlinear finite element method was applied to analyze the stress state and deformation performance of a total of 626 isolated RC shear wall components with rectangular section designed according to current Chinese codes. And parametric studies were made of the influence of shear span ratioλ, axial compression ratioμ, ratio of flexural capacity to shear capacity m, longitudinal reinforcement ratioρand volume stirrup ratioρv of confined boundary members.3) Based on the summaries and analysis of the experiment data of 72 isolated shear wall specimens in existing literatures and the finite element results of 626 isolated shear wall components in the paper, the more reasonable and realistic failure mode criteria of isolated RC shear wall components with rectangular section are proposed while taking into account the influences of shear span ratio, ratio of flexural capacity to shear capacity and longitudinal reinforcement ratio of confined boundary members.4) The ultimate status criteria for isolated shear wall components are proposed on the basis of the stress state, deformation and failure characteristics of the components. The demands of deformation limits for isolated shear wall components under frequent, fortified and severe earthquakes are put forward according to the seismic design requirements. Then, on the basis of summing up the finite element results of the 626 isolated RC shear wall components in the paper, the deformation performance index and its limits of the isolated RC shear wall components with rectangular section based on Chinese codes are proposed. The plastic drift is selected as the deformation performance index of the isolated shear wall components with 1.0≤λ<2.5, and the limits of the plastic drift p△lim under fortified earthquakes and the corresponding value a△lim under severe earthquakes are presented for the isolated RC shear wall components with rectangular section and with 1.0≤λ<2.5 under different parameters. Meanwhile, the plastic rotation of plastic zone is selected as the deformation performance index of the isolated shear wall components withλ≥2.5, and the limits of the plastic rotation pθlim under fortified earthquakes and the corresponding value aθlim under severe earthquakes are presented for the isolated RC shear wall components with rectangular section and withλ≥2.5 under different parameters.5) The loading characteristics and the determination method of coupled shear walls are first discussed. The components division method for coupled shear wall is given according to the stiffness ratio of coupling beam to wall pier and their stress state. Then, the coupled shear wall is divided into relative simple coupling beam components and wall pier components, which will set up the foundation for the study of performance status of coupled shear wall.6) The stress state and deformation performance of 14 five-story rectangular section of RC coupled shear walls designed according to Chinese codes were studied by using reliable nonlinear finite element method. The overall coefficient of the coupled shear wall satisfies the condition of 1≤α<10 and the span-to-depth ratio of the coupling beam is greater than or equal to 2.0. Based on the finite element analysis results, the deformation performance of coupling beam components and its impact on coupled shear wall are preliminary studied. The differences and similarities of the stress state and deformation performance between wall pier components and isolated shear wall components are compared. Then the ultimate status criteria, the deformation performance index and its limits for RC wall pier components with rectangular section based on Chinese codes are proposed. For the wall pier components withλ≥2.5, the plastic rotation is more reasonable taken as the performance index than the story drift, and it can better reflect the weak parts and destruction of wall pier components. 7) The differences of the performance index and its limits of RC shear wall components with rectangular section between the value determined by the paper based on Chinese codes and that recommended by American codes and the causes of the differences are analyzed.The study of the performance index and its limits of shear wall components based on Chinese codes provides a favorable basis for the transition from the traditional method to the performance-based approach of Chinese seismic codes.