Experimental study on seismic behavior of concrete walls reinforced by PC strands

A simple reinforcing method is proposed to make drift-hardening concrete walls with reduced residual deformation and crack width. In this method, high strength PC strands are utilized as the longitudinal reinforcing bars placed in the edge zones of wall panel in lieu of general normal-strength deformed rebars. To verify effectiveness of the proposed method, four concrete walls were fabricated and tested under reversed cyclic lateral loading while subjected to constant axial compression with an axial load ratio of 0.13. Two walls were reinforced by PC strands to represent the proposed drift-hardening walls, and the others utilized normal-strength deformed rebars, representing the code-based ductile walls. The code-based walls performed in a ductile manner until 2.5% drift before significant strength degradation occurred. The wall utilizing PC strands and properly confined by transverse reinforcement in the wall panel exhibited significant drift-hardening capability up to about 2.5% drift. The residual drift and crack width of this wall measured after unloading from the 2.0% drift were 0.41% and 0.16 mm, while those of the ductile walls were 1.06% and 0.8 mm, respectively. Comparisons with the test results have indicated that the calculated flexural capacities by AIJ code provisions agree fairly well with the test results and that utilizing ACI code provisions and AIJ code equation can give a reasonable evaluation of the failure mode of concrete walls, drift-hardening and ductile.