Amirkabir Journal of Civil Engineering

Amirkabir Journal of Civil Engineering

Comparison of Conventional and Energy-Based Methods in Fragility Assessment of Steel Moment-Resisting Frames

Document Type : Research Article

Authors
Hossein Dehrouyeh 1
Ali Delnavaz 2
reza Farokhzad 2
mehran seyed razaghi 2
1 PHD candidate, Department of Civil Engineering, Qa. c., Islamic Azad University, Qazvin, Iran.
2 Assistants professor, Department of Civil Engineering, Qa. c., Islamic Azad University, Qazvin, Iran.
10.22060/ceej.2026.25017.8374
Abstract
Methods for generating fragility curves in buildings are generally based on the maximum inter-story drift. Moradi and Abdolmohammadi (2020) proposed an energy-based method. They stated that by considering the plastic strain energy in high-rise structures as an engineering demand parameter, fragility can also be derived. The aim of this study is to compare the maximum inter-story drift-based method and the energy-based method in 4-, 8-, and 12-story steel buildings. For this purpose, after initial design, the structures were modeled nonlinearly in PERFORM-3D software and subjected to 20 near-fault ground motion records. Incremental Dynamic Analysis (IDA) curves were extracted using both the energy and maximum drift methods and compared with each other. Finally, by calculating the energy limit states at two performance levels—Life Safety (LS) and Collapse Prevention (CP)—the fragility curves at these two levels, along with the elastic level, were computed and compared with the maximum drift-based method. The results showed that in low- and mid-rise structures, the maximum drift-based method provides a more conservative fragility estimation compared to the energy-based method. For example, the probability of exceeding 50% of the LS level in the energy-based method for 4-, 8-, and 12-story buildings occurs at peak accelerations of 1g, 1.25g, and 1.45g, respectively, while in the conventional method this occurs at peak accelerations of 0.65g, 0.9g, and 1g, respectively.
Keywords
Fragility
Energy-based method
Drift-based method
Incremental Dynamic Analysis (IDA) curves
Steel moment-resisting frame
Subjects
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Amirkabir Journal of Civil Engineering
Volume 58, Issue 2
2026
Pages 243-266