The aim of this project is to analyse the effects of train induced vibrations in a steel Langer beam bridge. A case study of a bridge over the river Ljungan in Ånge has been made by analysing measurements and comparing the results with a finite element model in ABAQUS.
The critical details of the bridge are the hangers that are connected to the arches and the main beams. A stabilising system has been made in order to reduce the vibrations which would lead to increased life length of the bridge.
Initially, the background to this project and a description of the studied bridge are presented. An introduction of the theories that has been applied is given and a description of the modelling procedure in ABAQUS is presented.
The performed measurements investigated the induced strain and accelerations in the hangers. The natural frequency, the corresponding damping coefficients and the displacement these vibrations leads to has been evaluated. The vibration-induced stresses, which could lead to fatigue, have been evaluated.
The measurement was made after the existing stabilising system has been dismantled and this results in that the risk of fatigue is excessive. The results were separated into two parts: train passage and free vibrations. This shows that the free vibrations contribute more and longer life expectancy could be achieved by introducing dampers, to reduce the amplitude of the amplitude of free vibrations.
Author: Andersson, Andreas | Malm, Richard