Investigation on the behavior of special moment frames with high-strength reinforcements subjected to cyclic loading

Abstract High-strength reinforcement (HSR) application has many advantages, like: decreasing expenditures and construction time, improving construction quality and so on. However, their application has been limited in special moment frames by several building codes. This limitation is due to some challenges, like: the reduction of the overall ductility and serviceability of the reinforced concrete (RC) structures. In this research, the effects of the HSR application on the stiffness, drifts, energy dissipation, ductility, cracking patterns and damage indices of four special moment frames are investigated experimentally. These special moment frames have the same geometry and equivalent amounts of the reinforcements (with yield strengths of 500 and 580 MPa). The frames are tested under cyclic loading. The results indicate that all the frames achieved drift ratios exceeding 4% before they show a critical decline in lateral strength. Moreover, replacing the Grade 500 MPa bars with the reduced amounts of the Grade 580 MPa bars led to the comparable deformation capacity. Experimental observations also show that by using higher strength reinforcements, the cracking patterns change: the higher the yield strength, the wider and deeper the cracks.