Experimental study and mechanism analysis of out-of-plane seismic performance of reinforced concrete shear walls

Compared with the in-plane seismic performance， the out-of-plane seismic performance of reinforced concrete shear walls is weak and usually neglected， which leads to an inadequate study of the out-of-plane damage mechanism of shear walls and a lack of clear protective measures， and the overall seismic performance of shear wall structure is also unsafe， which needs urgent attention. In order to compare the similarities and differences in seismic performance of reinforced concrete shear walls when subjected to in-plane and out-plane loads in different directions and to clarify the key influencing factors， low cyclic loading tests are conducted on typical shear wall specimens in-plane and out-plane directions， and the macroscopic test phenomena， hysteresis curves， skeleton curves， stiffness degradation curves， energy dissipation capacity and ductility in both directions are compared and analyzed. The moment-curvature simulations of shear wall sections in both in-plane and out-plane directions are analyzed， and the results obtained from multiple sets of constitutive models are compared with the experimental results. Combined with the finite element variable parameter analysis， the effects of parameters such as axial pressure ratio， wall thickness， height-to-width ratio and concrete grade on the seismic performance of in-plane and out-plane are analyzed. Based on the endurance time analysis， the time-history response of structural displacement with seismic magnitude is studied. The results show that the seismic performance of shear walls outside the face is significantly weaker than that inside the face， and the bearing capacity is only 1/20~1/15 times of the latter， among which the wall thickness and height-width ratio are the main parameters affecting the seismic performance inside and outside the face. The out-of-plane nonlinear analysis of the cross-section can be performed more accurately and quickly by using the principal structure model proposed in this paper and some traditional principal structures. In the seismic design of shear walls， especially for the single directional wall with less structure， both in-plane and out-of-plane seismic performance should be ensured， and the thickness and aspect ratio of shear walls should be reasonably controlled. Wall damage assessment by using elastic-plastic energy dissipation difference rate has the characteristics of obvious differentiation and reasonable threshold value.