Abstract
A rigorous and efficient optimum design method for steel cable-stayed bridges is developed, in which cable anchor positions on main girder, height of pylon are dealt with as the design variables together with the sectional dimensions of the member elements of main girder, pylon and cables. The design problem is formulated as a minimum cost design problem subjected to the stress constraints which are taken from the Japanese Specifications for Highway Bridges. In the stress analysis, the stresses in the cantilever system at erection closing stage and in the continuous girder system at service stage are considered as the working stresses. The cost minimization problem is solved by using dual method with mixed direct/reciprocal design variables. The optimum solutions can be obtained quite rigorously and efficiently by the proposed design method. The optimum values of the design variables obtained are quite reasonable and well-balanced from the static analysis viewpoint. The significance of dealing with cable anchor positions and height of pylon as the design variables is also emphasized for the minimum cost designs of cable-stayed bridges.
