Out-of-plane shaking table tests for URM walls

Un-reinforced masonry (URM) walls are commonly used as in-fills for low-rise RC buildings in Taiwan, while they are usually considered fragile when subjected to out-of-plane loading due to the lack of reinforcement. Four full-scaled single-story RC frames with URM walls in different thickness and construction types were tested on shaking table for study on their out-of-plane failing behavior. Each specimen was subjected to a ground motion from Chi-Chi earthquake with the intensity magnified several times and a final sine-wave excitation for collapse. However, although horizontal cracks occurred at the top and the bottom edges of the walls in every specimen almost as soon as the tests started, only the post-laid walls began to split from the RC frame during the later stages of the loading procedure and eventually collapsed. The pre-laid walls with well-confined boundaries remained in the frames throughout the entire test. The test results suggest that increasing thickness of walls usually leads to slightly higher stiffness, yet there is no apparent relationship between thickness and out-of-plane strength in this test. Generally, specimens with pre-laid walls show higher strength and stiffness than the one with post-laid walls. Since all the specimens with walls show higher strength than the one without walls, the possible out-of-plane contribution of URM walls is confirmed in this test.