Distinct Element Modeling of Masonry-Infilled Steel Frames with Openings

Abstract

Numerical analysis of masonry-infilled steel frames (MISFs) is one of the greatest challenges faced by struc- tural engineers. This difficulty results from the presence of joints as the source of discontinuities and nonlinearities as well as the interaction of frame-infill panel. In spite of many studies performed on numerical modeling of solid MISFs, there are few studies on MISFs with openings. A 2D numerical model using the specialized distinct element software UDEC (2004) for the pushover analysis of MISFs with openings is developed. In this model, large displacements and rotations between masonry bricks are taken into account. A comparison between the results of distinct element modeling and the experimental results available in the literature showed a good correlation between them. Furthermore, It was found that the model has the capability to predict lateral load capacity, joint cracking patterns and explore the possible failure modes of MISFs with openings. Steel framed buildings are usually infilled with masonry panels as partition and surrounding walls. The composite steel-masonry framed building is called masonry-infilled steel frame (MISF) which has high lateral stiffness and load capacity. Under severe lateral forces, the surrounding frame interacts with the infill masonry panel increasing lateral stiffness and load capacity of the MISF. This is because, the frame and masonry infill panel deform in a bending and shear modes, respectively. In spite of the frame-infill panel interaction, the unexpected effects of infill panels are not usually taken into account in the analysis and design of such frames. Ignoring the structural effects of infill panels may results in wrong estimation of lateral stiffness, capacity and ductility of these frames. Since 1950's, many numerical and experimental re-