Multi-axial cyclic loading tests for RC shear walls of nuclear power plant structures

Abstract

Reinforced concrete (RC) walls have been widely studied through experimental testing. A great number of these existing studies considered only the in-plane loading cases, ignoring the out-of-plane loading effect on the in-plane structural response, although earthquake ground motions have multi-axis loading components. Some recent studies addressed the bidirectional loading effect on RC walls, and reported that the out-of-plane loading lowers the displacement capacity of RC walls. However, these studies are for flexural response of RC walls, and little experimental data for shear response of RC walls under bidirectional lateral loading is available. In this study, a series of cyclic loading tests were conducted to investigate the effect of multi-axial loading on the in-plane shear response of RC walls. A prototype nuclear power plant structure was selected, and a part of the prototype RC wall was manufactured as a test specimen, which was designed to have shear failure. Out of the five wall specimens manufactured for this study, two specimens were subjected to the same unidirectional lateral loading with different axial forces to investigate the effect of axial force on the wall response. Remaining three specimens were subjected to bidirectional lateral loading with different loading protocols. It was found that both out-of-plane loading and axial force can substantially impact on the in-plane shear strength and displacement capacity of RC walls.