Modeling of dry-stacked masonry panel confined by reinforced concrete frame

In order to increase the energy dissipation of wall/frame elements subjected to in plane shear loading a conceptually new system for masonry infilled RC frame has been proposed and proved as effective. The interaction between frame and infilled panel is considered as the major cause of the nonlinear behavior of structure. In this paper, the experimental results are briefly summarized and a micro finite element model is developed to simulate the monotonic response of the masonry infilled structure. A novel type of element called "initial gap element" is presented to simulate the gap between the frame and panel to allow the continual simulation of the response for the full load cycle. All the material parameters are experimentally evaluated. The initial testing included free vibration and cyclic tests on a bare RC frame followed by cyclic test on the RC frame infilled with a dry-stacked concrete brick panel. These results are used to verify the accuracy of the model. It is shown that the model is able to simulate the failure mechanisms exhibited by experiment including the crushing and cracking of the concrete frame and the diagonal compressive stress contribution of the masonry panel. The load-displacement response predicted by the model was also in good agreement with that obtained from the tests. Furthermore, the model was used for ultimate analysis, which discovered four typical stages of structural response of the dry-stack infilled RC frame and found the friction between bricks in the dry-stacked panel contributes significantly (about 50%) to the assembly.