Seismic Performance Assessment of Steel Concentrically Braced Frames (CBFs) Equipped with Crescent-shaped Braces (CSBs)

Asghari, Abazar; Tajik, Nima

doi:10.22059/ceij.2025.383680.2170

Seismic Performance Assessment of Steel Concentrically Braced Frames (CBFs) Equipped with Crescent-shaped Braces (CSBs)

Articles in Press

Authors

Abazar Asghari ¹
Nima Tajik ²

¹ School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran.

² Department of Civil, Structural and Environmental Engineering, State University of New York at Buffalo, Buffalo, NY, USA

10.22059/ceij.2025.383680.2170

Abstract

This paper focuses on studying the elastic and inelastic behavior of steel concentrically braced frames (CBFs) with crescent-shaped braces (CSBs) and proposes a novel seismic design approach due to the lack of existing seismic specifications. The results of the elastic analyses demonstrate a reduction in the lateral stiffness of the frame as the arm (ξ) increases. Specifically, when ξ reaches approximately one fifth of the length of the braced member, the lateral stiffness of braced frames becomes nearly equal to that of moment-resisting frames. The analysis results further verify that the strength and stiffness of braced members are not inherently coupled. The findings highlight that by specifying the appropriate value of ξ (arm length), the desired stiffness can be achieved. This implies the conventional concentrically braced members typically lack such a specification. Nonlinear analyses of braced frames confirm that frames braced with CSBs can be classified as Steel Special Concentrically Braced Frames (SCBFs) rather than ordinary concentrically braced frames (OCBFs). Nonlinear analysis indicates the response modification factor for this type of frame should be 3.5. Additionally cyclic behavior of frames braced with CSBs indicated that by increasing the value of ξ, more energy dissipation can be achieved during earthquake loading.

Keywords