Evaluation of seismic performance factors for buckling restrained braced frames

Özkılıç, Yasin Onuralp
Buckling restrained braces (BRBs) have been used recently in seismic zones due to their high energy dissipation capacity. Buckling restrained braces can yield under both tension and compression without buckling and they have balanced hysteresis loops. In this thesis, seismic performance factors given in ASCE 7-10 Minimum Design Loads for Buildings and Other Structures for buckling restrained braced frames (BRBFs) were evaluated. Pursuant to this aim, twenty four archetypes composed of single diagonal and chevron BRBFs were designed according to the United States provisions. The archetypes were subjected to Maximum Considered Earthquake (MCE) ground motions using 22 sets of Far Field records defined in FEMA P695. Elastic and inelastic time history analysis of these archetypes were conducted by using Opensees software. Cumulative brace axial strains, brace axial strains and interstory drift ratios were obtained from numerical analysis and compared with the requirements of AISC 341-10. The results show that the current codified value of deflection amplification factor under-estimates the deflection of lower stories and over-estimates the deflection of upper stories. To address this issue, deflection amplification factors that vary over the height of the structure was proposed. Archetypes were redesigned using proposed modifications and reevaluated using FEMA P695 Methodology. The results indicate that proposed modification was adequate to satisfy the requirements of AISC 341-10.  
Citation Formats
Y. O. Özkılıç, “Evaluation of seismic performance factors for buckling restrained braced frames,” M.S. - Master of Science, Middle East Technical University, 2016.