Inappropriate Detailing Impact Towards Ductility of High Rise Reinforced Concrete Moment Frames Building in High Seismicity Area

Abstract

Responding to human population and economic growth in Indonesia, high-rise building as supporting infrastructures has increased significantly in numbers in many big cities. Designing high-rise building, earthquake load shall be considered to create an earthquake-resistant building. However, the civil engineering practices in Indonesia are inappropriate to the current provisions. Many existing buildings, which were built based on previous earthquake-resistant building provisions, are not evaluated to adjust to the current earthquake-resistant building provisions. There is also inconsistency among civil engineers while applying provisions in design practices. Hence, a question arises whether the existing buildings which were designed using an inappropriate procedure are adequate enough to fulfill the necessary requirements of structural behavior and performance level as an earthquake-resistant building in high seismicity area. This paper presents structural analysis to evaluate impacts of various levels of detailing on ductility in high-rise reinforced concrete frame buildings. In the study, 20 story office buildings located in region with high seismicity area were designed. Five detailing levels of building designs were studied: one building used appropriate design while others not. The variations were differed by combining types of moment frame system (ordinary, intermediate, and special) and several values of response modification coefficient, R. The seismic performances of the buildings were then investigated by performing nonlinear time history analysis using seven pairs of scaled ground motions. From this analysis, ductility of five buildings were compared and evaluated. The evaluations were presented by performance level result and limited maximum story drift ratio result. Based on the findings, dynamic behavior for inappropriate designed buildings indicated vulnerable behavior of structure which was dominated with brittle behavior and exceed maximum drift limit. Due to the vulnerability, this paper proposes the necessity of immediate evaluation and retrofit for existing high-rise buildings which have inappropriate design in high seismicity area in Indonesia.