Improved brace fracture model for seismic evaluation of concentrically braced frames

•Existing brace fracture models fail to predict the fracture process observed from laboratory data.•Fracturing process concept logically explains brace fracture phenomenon.•Proposed fracture initiation model predicts brace fracture in a consistently reliable manner. Reliably predicting brace fractur...

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Bibliographic Details
Published in:Engineering structures 2020-03, Vol.206, p.110184, Article 110184
Main Authors: Faytarouni, Mahmoud, Shen, Jay, Seker, Onur, Akbas, Bulent
Format: Article
Language:English
Subjects:
Brace ductility
Computer simulation
Crack initiation
Crack propagation
Damage measure
Database of tested specimens
Deformation
Ductility
Ductility tests
Empirical analysis
Fracture initiation
Fracture mechanics
Fracturing process
Frames (data processing)
Mathematical models
Performance evaluation
Physical tests
Regression analysis
Research programs
Seismic analysis
Seismic response
Square hollow section brace
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Summary:•Existing brace fracture models fail to predict the fracture process observed from laboratory data.•Fracturing process concept logically explains brace fracture phenomenon.•Proposed fracture initiation model predicts brace fracture in a consistently reliable manner. Reliably predicting brace fracture is crucial in seismic evaluation of post-fracture performance of concentrically braced frames. This paper evaluates existing fracture models, proposes a new fracture initiation model based on a large amount of experimental data, and compares all models with the test results. The existing ductility-related empirical models and strain-related fiber models are evaluated by experimental tests. A comprehensive database of previously tested square hollow structural sections from different research programs is established to conduct a regression analysis leading to development of a fracture initiation model. The study concludes that the existing fracture models are unable to predict fracture events observed during physical tests. Furthermore, the existing strain-related fracture models, accessible to all users in OpenSees, fail to simulate the cyclic response of braces beyond initial inelastic deformation. The fracture initiation model proposed by this study depends on the reliable measure of ductility, and it has consistently predicted fracture initiations observed during the tests. The fracturing process concept, along with the proposed fracture initiation model, is able to simulate the cyclic response of the braces, whether they are tested as single brace members or in actual braced frames, throughout inelastic deformation, fracture initiation, fracture propagation, and terminal fracture stages, providing a much-improved tool for numerical simulation of the post-fracture response of concentrically braced frames.
ISSN:0141-0296
1873-7323
DOI:10.1016/j.engstruct.2020.110184