Seismic Performance Evaluation of Conventional and Offset Outrigger with Belt Truss Systems in Tall Buildings

Tall buildings are highly vulnerable to lateral loads such as wind and earthquakes due to their slender geometry and height. To enhance their seismic performance, structural systems like outriggers and belt dresses are widely adopted. Traditionally, outriggers are connected directly to the central core, but recent advancements have explored the use of offset outriggers, which are placed away from the core, offering design flexibility and improving internal space utilization. This study investigates and compares the seismic performance of three structural configurations: A Base model without outriggers, a model with conventional outriggers and a model with offset outriggers combined with belt trusses. The analysis was performed using STAAD.Pro, considering seismic loads as per IS 1893:2019. Key performance indicators such as lateral displacement, story drift, base shear, and overturning moment were evaluated to assess the effectiveness of each configuration. Results show that both outrigger systems significantly improved seismic performance compared to the baseline, with the offset outrigger and belt system achieving the greatest reduction in lateral displacement (up to 35%) and better drift control.