Cable-stayed bridges - Parametric study

Abstract

In this paper, the effect of number of cables and the length of central panel on the behavior of radiating-type cable-stayed bridges has been investigated. The study was carried out for double-plane bridges with 12, 20, 28, and 36 cables per plane, with side to main span ratios of 0.35, 0.40, 0.45, and 0.50, respectively. The bridges were analyzed by the stiffness matrix method, treating the bridges as two-dimensional structures. A uniformly distributed load of 10 kN/m (1 t/m) was considered over the entire length of the bridge. The computational work was carried out on an IBM 360 main frame computer. The investigation shows that maximum cable tension decreases rapidly with the increase in the number of cables. In general, the effect of length of the central panel on the sagging moment is significant; on the hogging moment, the effect of length is not appreciable. Both the hogging and sagging moments increase with the increase in the number of cables from 12 to 36. The parametric charts useful for the design of cable-stayed bridges, incorporating the foregoing parameters, have also been prepared. A comparison of the weight of steel in cables and girders, as well as the total weight of steel (cables and longitudinal girders only) in the harp and radiating arrangements was also carried out. In both harp and radiating bridges, the weight of steel decreases with the increase in the number of cables.