Numerical study: Effect of various link length to lateral force in eccentrically braced frame

Abstract

Eccentrically Braced Frame (EBF) is an excellent steel frame system for resisting earthquake forces. This frame shows good performance in terms of stiffness and has excellent ductility. When it is subject to a severe seismic event, the links undergo inelastic deformations and become the primary source of energy dissipation. However, the performance of EBF is strongly influenced by the length of the links that are an essential part of the EBF system. Links should be limited not be too short or too long because it relates to the stiffness and ductility of the frame. The study of EBF on the 80-90s also limits the ratio both of e/L not exceed 0.5 and the diagonal brace angle between 40°-60°. This research will review the influence of the length of the links varied from the e/L ratio of 0.005 to 0.38. This variation will divide the links into three types of yielding, i.e., the short link, intermediate link with shear dominance, and intermediate link with bending dominance. In this study, the behavior of various link lengths on Eccentrically Braced Frame will be evaluated using finite element analysis using MSC Patran and Nastran. The structure is modeled as a one-dimensional D-Braced EBF type that is given static monotonic load with displacement control. The results obtained in the form of loaddisplacement curves which will be analyzed in strength and ductility. In addition, an ultimate load normalization curve will be generated to obtain the load pattern for the various link length. The curve shows that the ultimate load on the EBF will decrease if there is an increase in link length. The significant decrease occurs when e/L > 0.2.