EXPERIMENTAL INVESTIGATION ON SEISMIC BEHAVIOR OF T-SHAPED REINFORCED CONCRETE SHEAR WALLS UNDER VARIED BIAXIAL LOADING PATHS

To study the damage mechanism and seismic behavior of shear wall with flange under a complex multidimensional earthquake, the uniaxial and biaxial quasi-static tests of five T-shaped reinforced concrete shear walls were carried out. The effect of biaxial loading on the failure mode, on the hysteretic behavior, on the bearing capacity, on the ductility and on the energy dissipation capacity of T-shaped walls were investigated, and the force mechanism and multidimensional seismic behavior of T-shaped walls under different biaxial loading paths were also analyzed. The research results show that the failure part of T-shaped RC walls under both uniaxial and biaxial loadings are concentrated at the bottom of the free end of wall segment. Biaxial loading aggravates the crack development and concrete spalling, and it has a greater impact on flange damage. There is an obvious correlation of the mechanical behavior of T-shaped wall between its two orthogonal directions. The internal force redistribution and local additional stress generated by biaxial loading would change the local stress mechanism and overall performance of T-shaped wall, that is, when the loading in one direction, the force in the orthogonal direction would change under a constant displacement. Compared with uniaxial loading, the bearing capacity under biaxial loading is reduced by 6.90% on average, the ultimate deformation capacity is reduced by 11.28% on average, the cumulative energy consumption in single direction is decreased, and the biaxial coupling effect increases with the loading paths alternating from cruciform to eight-shaped to rectangular. Due to the randomness of ground motion and the multidimensional coupling of structural response will significantly change the seismic capacity of RC wall with flange under a real earthquake, it is suggested to rationaly consider the reduction of bearing capacity and appropriately reduce the inter-story drift ratio limit in the aseismic design of shear wall structures.