Cyclic loading test for walls of aspect ratio 1.0 and 0.5 with grade 550 MPa (80 ksi) shear reinforcing bars

In the shear design of massive walls in nuclear power plants, high-strength reinforcing bars need to be employed to enhance the constructibility and economy of the walls. In the present study, walls with aspect ratios of 1.0 and 0.5 were tested under cyclic lateral loading to investigate the effect of 550 MPa (80 ksi) reinforcing bars on the shear strength of squat walls. The test parameters included the grade of shear reinforcement, the failure mode, and the presence of boundary hoops. The ratios of the test shear strength to ACI 349 prediction (that is, safety margins) were 1.54 to 1.90 and 1.11 to 1.38 for the general and seismic provisions, respectively. The test results of walls with 550 MPa (80 ksi) reinforcing bars were comparable to those of walls with 420 MPa (60 ksi) reinforcing bars for all three evaluations: failure mode, safety margin, and average crack width.