Journal of Civil and Environmental Engineering

Study of Equivalent Strength and Effects of the Type of Multi-story Steel Braced Frames

Abstract

Takayuki Kinoshita and Takumi Ito

In recent years, the terrible earthquake events that are not expected in the design process have occurred in the world. So, it is necessary to estimate the seismic performance accurately. This paper focuses on the energy absorbing efficiency of steel braced frames. Steel brace members in frames show the complicated and unstable behavior because many kinds of buckling and fractures are combined. And evaluation method of restoring force characteristics and capacity have been studied in enormous past researches, however, there are some problems to adopt for seismic design procedure. Also the response characteristics of steel braced frames are affected by the interaction between frames and braces. This paper suggests the analytical method to evaluate the energy absorbing efficiency of steel braced frames as equivalent strength. The equivalent strength is formulated with yield shear coefficient of the frame and slenderness ratio of the brace. Also, to verify the applicability of multi-story steel braced frames response analysis of two types of 5-story steel braced frames (X bracing, inverted-V bracing) is conducted. As compared with energy absorbing efficiency of the response analysis result, it is confirmed that the equivalent strength can be accuracy of plus or minus 20 percent or so.