This paper investigates the structural response of wide span structures where the primary structural system is cable-stayed roof, and aims at optimizing the design of such structures. Finite element analysis is carried out using commercial software taking into consideration the nonlinear formulation of cables. In order to check the accuracy and capability of the present approach, several examples are presented for nonlinear analysis of cable structures, and the response is found to agree with published results. Additionally, finite element discretization and nonlinear analysis are carried out for an existing cable-stayed roof structure under all possible loading conditions. A numerical study is conducted where four different systems are suggested for the same structure: plane truss, space truss, cable-stayed plane truss and cable-stayed space truss systems. For each system, structural analysis is made under all design load combinations and optimization of design in order to reach the least possible weight and cost. The numerical results indicate the capability of the proposed approach in predicting the forces and deformations of cable structures and optimizing the design of structural element. It was concluded that the space truss and the cable-stayed space truss providing efficient performance as well as economy.