Improving the Seismic Performance of Eccentrically Braced Frames Using Tie Elements

Abstract

In Eccentrically Braced Frames (EBFs), link beams in lower storeys may experience a high risk of vulnerability due to the nondistribution of plastic hinges in the frame height and this problem leads to the formation of the soft storey. To mitigate such vulnerabilities, successive link beams can be tied throughout the structure height employing tie elements to develop a tied EBF (TBF) system. Unlike many studies on K-TBFs with shear link beams, limited investigations have evaluated the performance of single diagonal TBFs and K-TBFs with flexural link beams. In this study, K-EBFs/TBFs refer to EBFs/TBFs having link beams with two braces and single diagonal EBFs/TBFs refer to EBFs/TBFs having link beams with one brace. K-EBFs with flexural link beams have drawn the attention of designers because these frames make more space in the architectural design to create larger openings. Accordingly, improving the performance of K-EBFs with flexural link beams is one of this research objectives. The results comparison for 18 2D EBFs with different storeys including K-EBF with shear behavior, K-EBF with flexural behavior, and single diagonal EBF with shear behavior indicated that tie elements in these models can increase energy dissipation capacity and distribute plastic hinges in the structure height. The results exhibited that not only this system performance was considerably improved using tie elements, but also offered better resistance against progressive collapse.