An optimal resizing technique for seismic drift design of concrete buildings subjected to response spectrum and time history loadings

In an effort to improve conventional trial-and-error seismic design methods that rely heavily on engineers' experience and intuition, there have been attempts to develop an automatic resizing technique for the optimal drift designs of concrete framework structures. This paper presents an effective numerical optimisation technique for the seismic drift performance design of buildings under multiple earthquake loading conditions. Specifically, an Optimality Criteria (OC) method is developed to minimize the construction costs subject to seismic drift performance constraints and member sizing constraints. The emphasis is first placed on the formulation of an elastic drift design problem from the response spectrum or time history loadings and then on the details of the OC method to produce the optimal drift design. Two building frame examples are presented to illustrate the effectiveness and practicality of the proposed optimal method. The optimisation algorithm demonstrates its ability in automatically adjusting the stiffness of structural members and in simultaneously considering multiple earthquake responses to produce an optimal design while satisfying all specified drift performance criteria.