Seismic behavior of drift-hardening precast concrete walls reinforced with SBPDN rebars

Abstract

Six precast concrete walls reinforced with weakly bonded ultra-high strength (WBUHS) rebars were fabricated and tested under reserved cyclic lateral loading and constant axial compression to investigate the seismic behavior of the precast drift-hardening concrete walls. The emphasis was placed on clarifying the proper embedded length for WBUHS rebars and verifying the influence of the shear span ratio. The experimental variables were the embedded length of the WBUHS rebar, the shear span ratio of the walls, and the axial load ratio. Test results indicated that if the embedded length of the WBUHS rebar, whose ends were anchored by nuts and a washer, was 20d (d is the nominal diameter of rebar) and/or longer, the precast walls could exhibit identical seismic performance to the cast-in-site walls and had sufficient drift-hardening capability up to at least 2.0 % drift ratio. Test results also showed that the larger the shear span ratio, the less the residual drift. The residual drifts after unloading from the 2.0 % transient drift were less than 0.4 % regardless of the axial load level and the shear span ratio. Furthermore, an analytical method was presented to evaluate the seismic behavior of the precast walls reinforced by WBUHS rebars. The analytical method can consider the effect of bond slippage of WBUHS rebars and the confinement effect by transverse steels placed in the boundary elements on the cyclic response of the walls. Comparison between the measured cyclic loops and the predicted ones has indicated that the proposed analytical method can predict the cyclic behavior of the precast walls very well in important aspects such as overall performance, the ultimate lateral resistance, and the deformation capacity.