Design optimization of reinforced concrete 3D structures considering frequency constraints via a charged system search

This paper presents an optimal design of three dimensional multi-story reinforced concretestructures using recently developed meta-heuristic algorithms, namely; the charged system search andthe enhanced charged system search. the design is based on the aci 318-05 code and loadings are basedon asce7-05. analysis of the structures is performed by the standard stiffness method. all membersare subjected to biaxial moments and axial loads. pre-determined sections are assumed for beams andcolumns, and the corresponding interaction curves are utilized to check whether the selected section foreach member is acceptable. the objective function is taken as the weight of the structure, and constraintsconsist of the slenderness of compression members, the maximum allowable drift of the structure and thenatural frequency of the structure. it should be mentioned that second order effects are also consideredand that the end moments of the columns are magnified when needed.first, a 7-story frame with 3 spans is considered and optimized. then, a sensitivity analysis is performedby optimal design of nine frames having 3 stories and 2 spans. in each story, different span lengths andloading conditions are assumed, and the results are compared.