Conceptual Seismic Design of Cable-Stayed Bridges

Cable-stayed bridges can be a very effective means of bridging large distances in both seismic and non-seismic regions. Their design, analysis, and construction can be very challenging, and fortunately there is a considerable amount of literature that can assist engineers with both the analysis and detailed design of cable-stayed bridges. It is less common, however, to find simple recommendations for the conceptual design of cable-stayed bridges, in particular for seismic loading. As such, this article reviews and discusses some of the important conceptual design considerations for cable-stayed bridges, first for gravity loads and then for seismic excitation. The advantages and disadvantages of different cable-stayed bridge solutions are highlighted, with review of deck sections, tower configurations in both the longitudinal and transverse direction, deck-to-pier connections, and cable arrangements, amongst other things. Reference is made to a number of real cable-stayed bridge solutions. After reviewing the important conceptual design considerations for cable-stayed bridges, a simple preliminary sizing procedure is proposed. The preliminary sizing procedure is intended to offer designers a quick but rational means of identifying reasonable member sizes for cable-stayed bridges that should then be verified through advanced analyses in the developed and detailed design stages of the project. A case study application of the preliminary sizing procedure is made for a three-tower cable-stayed bridge in Ecuador, and by comparing preliminary and final design member sizes it is concluded that the preliminary sizing procedure may be a useful tool for design.