Comparison of structural response of traditional and tied eccentrically braced frames

Braced frame system is one of the structural systems used to resist the lateral loads such as earthquake and wind loads. In the last decades, among the bracing systems, tied braces have been developed as a new alternative for eccentric bracing systems in steel structures. In the first part of this study, two, four, six and eight storey bare frames and tied braced frames having the same plan and five bays in each direction were investigated. In this regard, the effects of different levels of eccentricity (or link length) and various bracing cross-sections were considered. In the second part of this study, the traditional eccentric bracing system and tied bracing system effectiveness on the seismic behaviour of the eight storey frame were examined comparatively. For all frame model, the nonlinear pushover analysis were applied and the results in terms of the capacity curve, the normalized maximum base shear ratio and the normalized initial stiffness ratio were investigated. The results indicated a considerable enhancement in the earthquake performance of the braced structures, and it was observed that the tied braced frames had more lateral load carrying and energy absorption capacity than traditional eccentric braced frames.