Neighbour Matrix for Optimal Seismic Design of RC Frames for Minimum Total Life-Cycle Cost

Structures are subjected to different probable earthquake excitations in their lifetime, which have different destructive effects. Life-cycle cost analysis is an appropriate tool for assessing the structural performance to obtain the best economic scenario over its lifetime. Therefore, it is necessary to define a method for optimal seismic design with life-cycle cost objective. However, the nonlinear behaviour of structures under severe earthquakes and the need to synchronize the various constraints of the seismic code require use of innovative methods instead of optimal classical methods. In this paper, the total life-cycle cost of buildings is the optimization objective for the seismic design of reinforced concrete frames. Therefore, a simple novel optimization algorithm is introduced by defining "Neighbours Matrix". This algorithm reaches a path to minimize the objective throughout the steps, based on changing the objective function in "Neighbour RC frames". The results ofoptimumseismically design ofRC framesincluding 5-, 8- and 12-story frames indicated that this algorithm reached optimum RC frame with acceptable performance and few numbers of analyses. Also the convergence rate was high because when total life-cycle cost was the objective function, after two steps with a small number of analyses, the TLCC was decreased about an average 25%. The robustness ofthe algorithmwas confirmed by evaluation of the coefficient of variation of structures in the optimal path.