Deck stiffness selection in the design of long span cable stayed bridges

Abstract

The major objective of the study is to find a useful results on the deck stiffness selection in long span cable stayed bridges at the conceptual stage of design. Decision making involving deck stiffness selection and the choice of the number and spacing of cables to meet deflection criteria is complex and the engineer needs guidance on making early design decisions intuitively. With several assumptions, a model with pinned at one end and clamped at the other end with odd number of cables equally spaced in fan pattern originating from the clamped end was analyzed using stiffness matrix method. At the end of the stiffness matrix analysis, design guidance graphs for (deflection/span length) with deck stiffness was obtained for different number of cables for the worst case of loading for the model with uniformly distributed load throughout the bridge deck and an abnormal type of point loading in the mid span. The deflection limitations for highway bridges in general and cable suspended bridge were included in the graph to obtain the minimum deck stiffness. These, graphs achieved finally from the analysis are worthwhile in the first stage of providing design guidance at the conceptual design in the deck stiffness selection of long span cable stayed bridges.