Intelligent Life Cycle Cost-Based Framework for Seismic Design of Conventional Structures

It is well understood that the dominant approach in the seismic design of structures is to reduce the initial cost while meeting the required safety level, as dictated by compliance codes. Nevertheless, this approach often overlooks the long-term costs that are incurred over the lifetime of the structures. A comprehensive approach is thus required for a design based on life cycle cost (LCC), where both initial and long-term costs are considered. While LCC-based design has been employed on regular structures, irregular structures have not received adequate attention. This research aims to highlight the impact of irregularity on the LCC optimization of tall structures. To do this, a bi-objective heuristic optimization framework is developed to balance the initial and long-term costs. The framework is used to analyze six steel regular and setback irregular structures with 7, 10, and 13 stories. The structures are all designed to meet the life safety performance level. The findings show that the irregular structures reveal a higher sensitivity to variations in initial costs compared to regular structures, which are mainly buildings above 13 stories. We also show that reducing the LCCs of irregular structures requires a higher increase in the initial cost compared to regular structures; for example, in the regular and irregular 13-story structures, a 17% increase in the initial cost resulted in approximately 48% and 40% reductions in the LCCs, respectively. Overall, our results confirm that the long-term costs of irregular structures are more than those of regular ones; this is an important finding that should be considered for the seismic design of tall irregular structures.

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