Seismic performance evolution and transmission mechanism, design philosophy of cross-shaped steel reinforced concrete columns and the corresponding joints
1. College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China;
2. Nanjing Tech University, Nanjing 211816, China;
3. Key laboratory of disaster prevention and structural safety of ministry of education, Guangxi University, Nanning 530004, China;
4. Xi’an University of Architecture & Technology, Xi’an 710055, China
Abstract：In order to investigate the seismic performance evolution from steel reinforced concrete (SRC) columns to their joints, thirteen cross-shaped SRC columns and the corresponding joints were tested under the cyclic reversed loading to study the seismic failure mechanism and performance difference of the specimens. The effect of steel form, loading direction, shear-span ratio and axial compression ratio on the seismic performance of cross-shaped SRC columns, planar joints and 3D joints were deeply analyzed. The generalized prediction model of bi-directional shear carrying capacity of cross-shaped SRC columns and the corresponding joints was proposed considering the loading direction. The bi-compression-bending capacity of cross-shaped SRC columns was calculated and verified by using ZeroLength Element in OpenSEEs and by introducing the loading angle. The results show that when loading direction changes from 2D to 3D, the shear capacity and energy-dissipation capacity of cross-shaped SRC columns and the corresponding joints were enhanced accordingly. The displacement ductility coefficients in cross-shaped columns were the maximum, but those for planar joints were the minimum. When the test axial compression ratio is in the range of 0.5, the larger axial compression ratio may lead to higher shear capacity and energy-dissipating capacity of cross-shaped SRC columns and the corresponding joints. The ductility of cross-shaped SRC columns and the corresponding joints increases with the growth of axial compression ratio, when the test axial compression ratio is lower than 0.3; while the test axial compression ratio is over 0.3, the ductility of cross-shaped SRC columns and the corresponding joints decreases with the growth of axial compression ratio. The elastic and elastoplastic drifts of cross-shaped SRC columns and the corresponding joints are much larger than the requirement in Chinese Code. Finally, the design suggestion of reasonable steel form, the principle of axial compression ratio and the calculation direction of the most unfavorable earthquake action were proposed based on the comprehensive performance studies.
