Author(s)

P. G. Papadopoulos, J. Arethas & P. Lazaridis

Abstract

A simple method is proposed for the nonlinear static analysis of cable-stayed bridges, with emphasis on the analysis of cables. The bridge is simulated by a plane truss model. A short computer program, with less than 200 Fortran instructions, is used, for the nonlinear static analysis, by incremental loading, of the above truss model. Geometric nonlinearities are taken into account by writing the equilibrium conditions with respect to deformed structure, within each step of the algorithm. The sag effect of cables is considered by assuming them to be the axial structural members with the equivalent elasticity modulus of Ernst. The above method is applied on a typical cable-stayed bridge with a central span of about 200m. The results are found to be in satisfactory approximation with other published data. Seismic inertia loads, parallel to the bridge axis, are applied to all the nodes of the truss. These loads combined with dead loads only, cause, in the back-stay, a state near slackening, whereas when they are combined with traffic in the central span they cause overstress of the exterior cable of the central span. The above two affected cables are analysed by another short computer program, with less than 200 Fortran instructions, for the 3D nonlinear static analysis of a discretized isolated cable, for gradual prescribed displacements of supports. Inclusion of geometric stiffness allows the study of a taut cable as a stable structure. Even a state of the cable near slackening can be studied. The 3D analysis allows the consideration of wind pressure perpendicular to the cables’ plane. Keywords: cable-stayed bridge, truss model, incremental loading, sag effect, Ernst equivalent elasticity modulus, pylon, deck, seismic inertia loads, geometric stiffness, slackening.

Keywords

cable-stayed bridge, truss model, incremental loading, sag effect,Ernst equivalent elasticity modulus, pylon, deck, seismic inertia loads, geometricstiffness, slackening.