Seismic Performance of Reinforced Concrete Tall Buildings with Advanced Materials

Abstract

Utilizing new and advanced materials for reinforcing concrete structures in lieu of conventional steel bars could promote the response and behavior of concrete structures and provide reliable solutions for construction-related challenges in concrete structures. The ACI 318-14 code does not allow the use of reinforcement with a yield strength higher than 60 ksi in special seismic force resisting systems in high seismic regions. ACI 318-19 limits the yield strength of reinforcement to 80 ksi in special frames and 100 ksi in special walls for seismic applications. In the first part of this study, high strength reinforcement was used instead of conventional bars in order to investigate the impact on the seismic performance of a concrete tall building that has been adopted as a case study. In the second part of this study, an analytical study was performed utilizing shape memory alloy (SMA) bars as an alternative reinforcement for conventional steel bars in order to potentially improve the seismic performance of reinforced concrete tall buildings and reduce the residual strain upon subjecting the structure to severe earthquake shaking. The study building was evaluated for four cases of reinforcement: conventional steel Grade 60, high strength ASTM A706 Grade 80, and high strength ASTM A1035 Grade 100 and 120. The response parameters were evaluated with the acceptance criteria of the Tall Building Initiative, TBI guidelines. Depending on the results, all cases with different grades satisfied the requirement of the TBI guidelines. In addition, an equivalent performance was noticed clearly between cases reinforced with a reduced area of high strength reinforcement and the reference case reinforced with conventional reinforcement. The last case included both conventional steel bars and SMA bars which were used in specific regions where the plastic hinge is expected to occur. The performance of the case study building satisfied the TBI guidelines requirements. In addition, utilizing SMA bars improved the response of the building by eliminating the residual strain in reinforcing bars. Finally, choosing the proper reinforcement material for concrete structures could be the key factor for meeting performance criteria while providing solutions for some construction problems.