Advanced Steel Construction

Vol. 13, No. 3, pp. 273-292 (2017)


SEISMIC COLLAPSE ANALYSIS OF

CONCENTRICALLY-BRACED FRAMES BY THE IDA METHOD

 

Gang Li 1,2,3,∗, Zhi-Qian Dong 1,2,3, Hong-Nan Li 1,2,3 and Y. B. Yang 4

1School of Civil Engineering, Dalian University of Technology, Dalian, Liaoning Province, 116024, China;

2State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China

3Institute of Structural Control and Monitoring, Dalian University of Technology, Dalian 116023, China

4School of Civil Engineering, Chongqing University, Chongqing, 400045 China

*(Corresponding author: E-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.)

Received: 18 February 2016; Revised: 27 July 2016; Accepted: 2 September 2016

  

DOI:10.18057/IJASC.2017.13.3.5

 

ABSTRACT:

Steel concentrically-braced frames (CBFs) as seismic lateral force resisting systems have been widely used in seismic regions. The incremental dynamic analysis (IDA) is adopted to construct the collapse ductility spectrum for the CBF considering the P-Δ effect and sudden loss in strength and stiffness, which is physically more meaningful than existing baseline criteria. The design performance plot is constructed by newly combining the collapse ductility spectrum with ductility demand spectrum on the same figure, from which the threshold period and design ductility region for the frame are determined. A parametric study is conducted for the CBF over the full range of periods and parameters. The results show that the reserve capacity of the CBF contributes appreciably to collapse prevention, and the presented approach is more suitable for assessing the collapse of CBFs with dynamic instability. For moderate seismic regions, the threshold periods of the CBF determined by both the collapse ductility spectrum and existing baseline criteria are quite close. However, for high seismic regions, using the global drift angle limit may yield non-conservative results, since it fails to address the dynamic instability of CBFs with short periods.

 

Keywords:

Concentrically-braced frames, collapse limit state, incremental dynamic analysis, ductility demand spectrum, collapse ductility spectrum

 

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