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Steel and Composite Structures
  Volume 45, Number 1, October10 2022 , pages 83-100

Numerical investigation on seismic behaviors of midrise special moment resistant frame retrofitted by timber-base bracings
Ainullah-Mirzazadah and Saeed-Reza Sabbagh-Yazdi

    Timber is one of the few natural, renewable building materials and glulam is a type of engineering wood product. In the present work, timber-based braces are applied for retrofitting midrise Special Moment Resisting Frame (SMRF) using two types of timber base braces (Timber base glulam, and hybrid Timber-Steel-BRB) as alternatives for retrofitting by traditional steel bracings. The improving effects of adding the bracings to the SMRF on seismic characteristics of the frame are evaluated using load-bearing capacity, energy dissipation, and story drifts of the frame. For evaluating the retrofitting effects on the seismic performance of SMRF, a five-story SMRF is considered unretofitted and retrofitted with steel-hollow structural section (HSS) brace, Glued Laminated Timber (Glulam) brace, and hybrid Timber-Steel BRB. Using OpenSees structural analyzer, the performance are investigated under pushover, cyclic, and incremental loading. Results showed that steel-HSS, timber base Glulam, and hybrid timber-steel BRB braces have more significant roles in energy dissipation, increasing stiffness, changing capacity curves, reducing inter-story drifts, and reducing the weight of the frames, compared by steel bracing. Results showed that Hybrid BRB counteract the negative post-yield stiffness, so their use is more beneficial on buildings where P-Delta effects are more critical. It is found that the repair costs of the buildings with hybrid BRB will be less due to lower residual drifts. As a result, timber steel-BRB has the best energy dissipation and seismic performance due to symmetrical and stable hysteresis curves of buckling restrained braces that can experience the same capacities in tension and compression.
Key Words
    cyclic analysis; incremental dynamic analysis; OpenSees; pushover analysis; steel moment frame; Timber Base Bracing Alternatives
Ainullah-Mirzazadah and Saeed-Reza Sabbagh-Yazdi:Civil Engineering Department, K. N. Toosi University of Technology, No.1346, Vali Asr Street, Mirdamad Intersection, Tehran, Iran

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