APPLICATION OF STEEL PLATE SHEAR WALL AND TENSION-BRACING IN RETROFITTING OF STRUCTURES

A rehabilitation technique that utilizes a thin steel plateas a supplemental shear wall system for steel momentframes is described. In the proposed system, the plateand surrounding boundary elements are installed in themiddle of the bay, separate from existing columns (SW-TB =Steel Plate Shear Wall with Tension-Bracing). Thisgeometry intends to reduce the forces transferred to theexisting columns. In this paper, the behavior of steel mo-ment frames using the proposed system is investigated.Among the methods of retro tting of the steel frames,application of steel bracing system has been studied bysome researchers. The results of these studies show thatretro tting of steel frames by adding braces has dis-advantages such as increasing axial forces in adjacentcolumns, brittle behavior in the frame joints, bucklingthe bracing member, and creating a permanent deforma-tion on the frame. In order to remove these disadvan-tage researches such as the use of non-compression brace,buckling-restrained braces, dissipative bracing systems, displacement-restraint bracing and thin in ll panels areexamined. Steel plate shear wall systems have attractedmore attention in the past few years as one of the majorlateral-load resisting system in steel buildings. In thiscontext, many investigations have been conducted in dif-ferent countries. In this study, to eliminate the above-mentioned disadvantages, a SW-TB system is used toretro tting of a steel frame. Recent researches indicatethat this type of shear walls has a very good perfor-mance in comparison to its traditional form (i.e., SSW=Steel Plate Shear Wall). For this purpose, the Finite-Element Model (FE) of steel frame retro tted with steelshear walls and tension-bracing has been made. Theobtained results of this model are compared with Lab-oratory data. The comparison shows that the nite-element model produces similar results to those of theproposed method in the laboratory. After the experi-mental validation, this method is compared with threeother methods. The FE analysis results show that usingthis method causes the lateral resistance of the structureto increase as much as 50 percent with good ductility,and the need to enhance the lateral columns and foun-dations will be limited.