برگزاری دفاعیه دکتری مهندس اسراء نایل

     Steel Plate Shear Walls (SPSW) had shown good performance in past earthquakes as well as in numerical and experimental studies. Although the SPSW has considerable advantages, it has two major flaws including the low elastic-buckling capacity of the infill plate and significant stresses generated by the infill plate on the boundary columns. There are some techniques to overcome these shortcomings. Among the proposed methods, the semi-supported SPSW is accounted as the most effective method. The weak aspect of this system is the reduction of stiffness and strength of the system in comparison with the conventional SPSW. An innovative four-layer semi-supported SPSW was introduced recently that overcomes the mentioned shortcoming. The main frame and the wall compose this system (including two corrugated plates, two flat plates, and secondary columns). Since there is no connection between the wall and the mainframe, there is no stress transmission from the plates to the main columns. This fact reduces the ductility demand. As a result of the combination of two plates (corrugated and flat plates), the elastic buckling of the wall increases up to an entirely yielding wall. This results in a more cost-effective system. This research presents the results of a comprehensive numerical study to investigate the effect of plate thickness, wall length, and aspect ratio on the behavior of this system under the monotonic lateral load. To obtain the pushover curves, the ABAQUS software package of the finite element was utilized. The findings showed that, as the length-to-height ratio increases, the wall capacity increases. Furthermore, the required equations for achieving the pushover curve were proposed without the need for finite element (FE) simulation. The results showed a good match between the FE results and the intended relations. To consider the behavior of the system, the effect of the loading pattern as well as the number of stories (low to mid-rise structures) were investigated. Results indicated that structures under the uniform loading pattern show a stiffer response, more than 1.27 times than those under the triangular loading pattern. Also, by increasing the height of structures, the effect of the loading pattern is increased, which reaches 37%. In addition, a simple model for the analysis of the system using SAP2000 was proposed. The main aim of the simple method is that analysis using SAP200 is more simple than ABAQUS. In this proposed method, the steel infill plate is replaced by a truss member. This method can be easily used in structures with a high number of floors, which speeds up the analysis and design of structures. A comparison between finite element results (ABAQUS)and the proposed model using SAP2000 indicates the high accuracy of the proposed method.

Keywords: SPSW; Stiffness; Ductility; Strength; Over strength