Recently, many experimental and numerical studies have been conducted about progressive collapse. Majority of them have been involved in frame structures and in alternative load path analysis method. Main mechanism of load transforming after removing a member, is beam catenary/tensile behavior which is mentioned in several works. However, other mechanisms such as slab membrane action or non- structural elements contribution maybe possible. Infill panel contribution as non-structural element in redistribution of loads and its effective role, is a subject which have recently attracted researcher's attention. Additionally, frames behavior depends upon characteristics such as opening dimensional ratio, contact surface, materials type etc. Each of them makes changes in capacity and stiffness of infilled frame. Gaps which have located in contact surfaces of infill panel and frame, significantly affect members and infill interaction. These maybe have been considered on the basis of defects in masonry work manship or requirements. Therefore, studies demonstrate that these have significant effect on capacity and stiffness of infill. Present study has investigated effect of width size frame as well as location on its separator gaps on infilled frame behavior. The main aim of this study is how infill contribution influences on redistribution of loads in presence of gaps.
In order to accomplish current work goal, structure finite element model was developed in SAP 2000 software and non-linear dynamic analysis was conducted on it. Given panel was concrete sandwich panel type. This infill was modeled by nonlinear layered shell element frame members was two-node frame element, and member plastic behavior was considered assigning by fiber hinge. Results depicted when gaps width increase to 50 mm, cause vertical displacement increase 70 percent comparing with without gap model. Also, it was observed that the rebar stress reach to yield limit. It was concluded that interfacial gaps s