Assessing seismic response in dual tower connected structures at different storey levels through fixed and flexible connections

Abstract Dual tower structures with sky bridges are statements of height and iconicity. These buildings serve various purposes, such as open conventional circulation, monumental sculpture sightseeing, fire evacuation, swimming pools, and other physical amenities. In the context of Nepal, very few scholars have studied sky bridges in tall buildings, necessitating the need for further study. Skybridges are horizontal connectors added at certain heights, which contribute to the coupling effect of adjacent towers and alter the predicted regular dynamic load-induced responses. This study examines the configuration of connected sky bridges, both rigidly and using passive isolated connections, excited by a set of three time-history ground motions. A nine-story dual tower with a connecting bridge of 14 m by 8 m, connected to the two grid perimeters of the towers, is considered. The study primarily investigates the efficacy of using isolators over conventional rigid connections, specifically lead rubber bearings (LRB) and high-damping rubber bearings (HDRB). The overarching objective of study is utilization of isolators to enhance building time and different seismic parameters to help minimize seismic vulnerability and achieve economically optimized structural design. Non-linear dynamic time history analyses are conducted on three distinct dual tower structural systems: fixed, LRB-isolated, and HDRB-isolated corridors, across three connection scenarios: corridors situated on the first and second floor, the third and fourth floor, and the sixth and seventh floor are considered. By comparing the analysis results with and without isolators, the effectiveness of LRB and HDRB is assessed. This study addresses fundamental design considerations to understand the optimal placement of sky bridges in the global system through the decoupling behavior of independent towers and their response to seismic dynamic responses, highlighting the advantages of isolator integration.