Optimum design for unbonded posttensioned precast concrete frames with damping

Abstract

SummaryPrecast concrete facilitates the construction process using durable and rapidly erectable prefabricated members to create cost‐effective and high‐quality structures, which has been widely used in some areas including those with high seismicity. A member of this precast structure family, the unbonded posttensioned precast concrete frames with damping, was proposed in the Precast Seismic Structural Systems (PRESSS) program. The PRESSS had presented a design procedure for the new system, which requires a time‐consuming iteration using trial and error. The aim of this study is to develop an automatic optimum design procedure as an alternative to the design of this system. Specifically, the objective of the optimum process is to find the minimum area of PT tendons, the maximum area of mild steel reinforcement, and the minimum unbonded length for mild steel while obtaining the maximum energy dissipation, maintaining moment capacity similar to design moment, and achieving zero residual drift, simultaneously. To this end, computer program MATLAB was utilized to develop an optimization design procedure using a genetic algorithm (GA). Comparing the results with that from the existing method indicates the proposed optimum design program is accurate, efficient, and direct. In addition, the program can present the optimum result within 1 min. Therefore, the existing iterative, step‐by‐step design method could be replaced.