Seismic Response and Reinforcement Efficiency of an HDRB-Isolated Reinforced Concrete Lecture Building in Jakarta

Abstract

This study evaluates the effectiveness of high-damping rubber bearing (HDRB) base isolation in reducing seismic demand and improving structural design efficiency of an 11-story reinforced concrete lecture building on soft soil in Jakarta. A fixed-base model and an HDRB-isolated model were developed in ETABS using response-spectrum analysis based on SNI 1726:2019. The HDRB system was modeled as an isolation layer with lateral flexibility, vertical stiffness, and hysteretic damping behavior. The comparison includes natural period, seismic base shear, interstory drift, lateral restoring force, isolator compressive stress, and reinforcement demand of beams and columns. The results show that HDRB lengthened the fundamental period to 4.758 s in the X-direction and 4.322 s in the Y-direction. This period shift reduced seismic base shear by 46.94% and 33.62% in the X- and Y-directions, respectively, while maintaining interstory drift within allowable limits. The isolator stress check satisfied the allowable compressive stress, with a maximum utilization ratio of 98.01%. Furthermore, HDRB simplified beam reinforcement from 18 to 7 beam types and reduced longitudinal beam reinforcement by 19.3%. These findings indicate that HDRB base isolation improves seismic response and supports more efficient reinforced-concrete design.