Multi-objective optimization of high-rise buildings with outrigger systems subject to seismic loads

Achieving highly accurate global optimization of high-rise buildings to balance safety and economy while addressing uncertainties is critical in structural design. This paper introduces a comprehensive multi-objective optimization method for high-rise buildings with single outrigger systems subjected to seismic loads, utilizing the NSGA-II algorithm. The optimization addresses two computing objectives: minimizing structural weight and maximizing either structural seismic performance or reliability. Initially, updated probabilistic demand models incorporating additional structural features are developed using a database derived from 3D nonlinear time-history analyses for three distinct single-outrigger system configurations. These models consider input feature uncertainties, enabling predictive fragility assessments. Subsequently, multi-objective global optimization is executed using these enhanced probabilistic demand models in combination with the NSGA-II algorithm. The optimized designs, balancing structural weight and reliability, exhibit improved robustness due to comprehensive incorporation of parameter uncertainties into the fragility assessments.