Evaluation of brick infill walls under in-plane and out-of-plane loading

摘要

In this paper, the in-plane (IP) and out-of-plane (OP) interaction of masonry infill walls with various length-to-height ratios and vertical forces from dead and live loads are studied. For this purpose, calibrated numerical simulation for IP and OP behaviors of infilled frames has been exploited. In this method, first, the vertical loads are applied, then increasing IP displacement is imposed at the top of the models and finally OP demands are applied to the walls up to their failure. Two different methods of applying OP loading are studied: increasing static uniform pressure on the wall, and increasing dynamic acceleration. Three levels of IP displacement demands are considered: at the first reduction of tangential stiffness for IP force-displacement response, at the maximum IP strength, and at the displacement related to 20 % reduction of IP strength. The results obviously show that up to the point of the maximum IP strength capacity, the OP behavior of the considered models slightly enhanced due to the effects of improved arching actions originated from the development of IP compressive diagonal struts. Moreover, slight differences exist between the static and dynamic loadings in OP direction, hence proving the accuracy of the equivalent static loading in determining OP capacity for the studied infilled frames. Comparing the results of masonry infilled frames with those of the corresponding masonry walls indicate that the IP displacements negatively affect the OP strength in the latter, even at small IP displacement demands; however, the rate of OP strength reduction in larger IP drift ratios is lower compared to that of the corresponding infilled frame.