Analysis of Jointless Bridges due to Horizontal Actions and Soil-Structure Interaction

Sammanfattning: Bridges constructed without joints function to take care of forces by introducing bending moments to the stiff connections. Jointless bridges, also called integral bridges, in different appearances are built all over the world, and are popular due to their advantages regarding life cycle cost. Usually the dimensions of the structural parts, especially the backwalls, tends to be large and the elements are heavily reinforced. By crediting the interaction between a bridge and the surrounding soil in the design work, material can be saved. Soil-structure interaction is a complex phenomenon where the boundary between soil and bridge may be modelled as springs with the same stiffness as the soil. The dissertation studies a method of FE modelling of the deformations and section forces, and also the extent of the soil-structure interaction, by introducing linear springs at the surface between soil and structure. The work is carried out by investigating two bridges, one fully integrated abutment bridge and one bridge with backwalls (sv. ändskärmsbro). The bridges are solely loaded by horizontal forces, e.g. braking forces, temperature movements and earth pressure. An initial stiffness of the soil is chosen, and from there, with some help from measurement data, the results from the FE model has then been compared to both calculations of a simple load case, as well as measured data, to find the proper soil stiffness. It is found that no sufficiently good convergence of the stiffness can be found from the measurement data, but the method shows good potential of working if more and more detailed analyses are made.