Method to Improve Seismic Performance of RC Moment-Resisting Frames Using Geometric Optimization

This article presents an optimization method to determine the column dimensions that maximize the fundamental frequency of a building, which translates into a highly efficient computational algorithm for approximately solving this optimization problem. A thoroughly detailed example is provided for a 10-story building whose elastic behavior is analyzed using a three-dimensional model, employing a two-dimensional fiber model to assess its inelastic performance. The results show that, compared with the classical design, which has columns of uniform depth, the maximum elastic drift is reduced by 10% and that the drift demand decreases on the lower stories of the building. In addition, the overstrength of the structure and its ductility are increased by between 10 and 30%. Similar improvements are also observed in a second example for a five-story building, showing that the method is useful at least for midrise buildings. (C) 2015 American Society of Civil Engineers.