Life Cycle Cost Optimization of Earthquake-Resistant Steel Framed Tube Tall Buildings

Past earthquakes revealed that while fulfilling the requirements of the conventional design codes guarantees the life safety of the occupants, considerable economic losses may still be incurred. This highlights the importance of considering life cycle losses in the design procedure of structures. In this research, the significance of the life cycle seismic risk costs in the optimal design of steel framed tube tall buildings is investigated. Typical 20- and 40-story buildings are optimally designed based on three approaches: the code-based, the cost-based, and the fixed weight approach. The first approach only minimizes the initial cost of the building while in the second and third approaches the total cost of the building in its lifetime is considered. Endurance Time (ET) method is used as the tool for seismic life cycle cost analysis. The requirements of the building codes are treated as the optimization constraints and the resulting problem is solved using the gradient-based algorithms. The results indicate that the cost-based approach results in the best practical design with the minimum total cost in the lifetime. The design based on the fixed weight approach reveals that the code-based design of tall buildings will not necessarily lead to the most economical use of material. Using ET method as the analysis tool along with the gradient-based algorithms as the optimization tool provides an efficient framework for the optimal seismic design of high-rise buildings based on life cycle costs.