Analysis of location, acceleration, force and ductility parameters in buckling-restrained braced frames

Abstract

- Sudden buckling and failure of bracing members in severe earthquakes reduces the efficiency of braced steel frames. The weakness can be modified and the efficiency of the bracing members can be increased by preventing the sudden buckling and failure of the bracing members. In this dissertation, we introduce a new type of braces called buckling restrained braces (BRB). This brace consists of a steel core and a part resisting against buckling. Different models have been proposed for the buckling restrained part. But the most prevalent of which is the use of a concrete layer around the steel core. Understanding the components of this type of brace, we calculate the critical load of some samples of these braces using ANSYS software with the load obtained from the analysis being compared with the load calculated by the Euler relation. Then, the behavior of ordinary buckling- restrained braced frames is compared in both linear and nonlinear ways using El Centro seismic acceleration mapping. Bracing the frames is performed in two coaxial and eccentric ways. In the coaxial mode, 8-foot and braces are used, while in the eccentric mode, 8-foot open braces are applied. To demonstrate the accuracy of the software, the results were compared with the those obtained by other researchers. The results indicated that these types of braces serve as a damper in the frames by preventing the buckling of the member and were found to be very effective in reducing the structures being displaced in severe earthquakes.