Out-of-plane shaking table tests on unreinforced masonry panels in RC frames

Shaking table tests were conducted on four full-scale single-story structures to investigate the out-of-plane behavior of unreinforced masonry (URM) panels in RC frames. Specimens included one pure frame, two frames with confined masonry panels of different thicknesses, and one with infill panels. Every specimen was subjected to single-axis ground motions with the intensity magnified each cycle until the structure exhibited severe damage. With strong boundary restraints, the confined masonry panels exhibited notable resistance to out-of-plane inertial forces via the arching mechanism. Infill panels also showed arching at low motion intensity, but separated from the boundary frames at higher intensity and collapsed under the inertial force caused by their self-weight. Wall thickness/slenderness was found to have a significant influence on out-of-plane strength and stiffness. An analytical model for the out-of-plane behavior of confined masonry panels in accordance with the rocking mechanism is also presented. Comparison with experimental results showed that this model affords accurate and conservative estimates for force and deformation capacities. It also suggests that the out-of-plane deformation capacity of a confined masonry panel is proportional to its thickness.