Energy-based collapse assessment of concentrically braced frames under mainshock-aftershock excitations. (January 2023)

• Record Type: Journal Article
• Authors: Pouya, Armin; Izadinia, Mohsen; Memarzadeh, Parham
• Is Part Of: Structures. Volume 47(2023)
• Page Start: 925
• Page End: 938
• Publication Date: 2023-01
• Subjects: Collapse mechanism -- Concentrically braced frames -- Mainshock-aftershock effects -- Energy dissipation modes; Structural engineering -- Periodicals; 624.1
• DOI: 10.1016/j.istruc.2022.11.119
• Languages: English
• ISSNs: 2352-0124

Abstract

Abstract: Concentrically braced frames (CBFs) collapse mainly because of soft story formation at one or a few stories in which excessive brace buckling occurs. This study provides an intuitive understanding of the collapse mechanism of CBFs with 3–18 stories subjected to mainshock-aftershock sequences. Such understanding will support development of design methods that preclude low-capacity collapse modes specially under multi-shock excitations. This paper assesses the collapse mechanism as a stage in which the imposed seismic energy fails to dissipate and eventually leads to uncontrolled kinetic energy. The investigation focuses on the role and distribution of the various energy measures and different dissipating mechanisms throughout the structures. The employed structural models simulate softening-induced dynamic instability by modeling various inelastic damage modes including buckling of the brace members. Collapse mechanism is identified for various combinations of the utilized mainshock-aftershock pairs that are gradually scaled following the IDA process. The distribution of input and dissipated energies along various stories reveals the role of upper stories in damping the imposed energy. Furthermore, the similarity between the height profile of the residual drifts and the story imposed energies highlights the characteristic of the structures in adapting their drift response to a mode with the highest energy absorption.