A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1989

The static behaviour of a typical segment of the orthotropic steel deck of the Rama IX cable-stayed bridge under heavy wheel loads is analysed. Two types of structural models are investigated, i.e. , a three-dimensional (3-D) finite element system using shell elements is employed to analyse the spatial stress distribution in the pavement under wheel loads; and a plane strain (2-D) model of the cross-section is used to investigate the stress distribution and deformation in the asphaltic concrete pavement. The effect of the position of the wheels relative to the longitudinal stiffeners is also studied using different 3-D and 2-D structural models. In the 3-D analysis linear-elastic material behaviour is assumed whereas in the 2-D model elasto-plastic behaviour of the asphaltic concrete is also assumed. A parametric study is carried out to cover the whole practical range of pavement stiffness . Large reductions in the stiffness of asphaltic concrete are mainly caused by temperature effects which for the deck surface of the Rama IX cable-stayed bridge can exceed 60 °C. All finite element analyses of the orthotropic steel bridge deck models have been carried out by the educational version of the computer program ANSYS. The results clearly show that the asphalt pavement and the steel deck plate act compositely, this leads to a significant reduction in the stresses in the steel deck plate. It is concluded that a stiff pavement (concrete deck) is most suitable for an orthotropic bridge deck subjected to high axle loads and high temperatures.