The Effect of Opening on Stiffness and Strength of Infilled Steel Frames

Infilled walls are the major non-structural elements which have significant effects on the seismic behavior of structures. The shape and strength of the brick elements are the main parameters affect the strength of the walls. In addition existence of openings may have a reduction effect. To increase the strength of the wall and to improve its behavior, the borders of the openings may be strengthened. In this paper, a one-story one-bay infilled steel frame which have been experimentally tested is modeled numerically and analyzed by commercial software ATENA. The wall was made of hollow clay tiles and cement mortar. The infilled frame was modeled under monotonically increasing loads until the failure. The numerical model is verified by comparing the cracking shape and the load-drift curves of the experimental and numerical models. Based on this numerical model, investigations on the effect of openings with different size and locations on the in-plane behavior of the walls are conducted. The effect of the strengthening of opening borders is probed additionally. Observations showed that the effect of openings is negligible for the opening with less than 10% area of the wall. In other cases, the lateral strength of the infilled frame reduced by 20-80% based on the size and location of the openings. The strengthening of all borders of openings with L-shaped steel angels can improve the behavior. The arrangement of these border elements may be changed to show better performance.