Bridges

Vehicle induced dynamic effects on bridges are one of the most complex phenomena in bridge engineering. Most of the international bridge design standards and codes of practice provide limited guidance or none for design against dynamic effects. It is partly due to large number of variables involve and difficulties in quantifying design/assessment parameters.

Recently, a steel concrete composite bridge was reported to exhibit vehicle induced vibration. Ultimate Limit State (ULS) structural assessment confirmed that the bridge has adequate structural capacity for ULS loads. A field instrumentation exercise comprising digital multi-axial accelerometers, digital inclinometers and foil type strain gauges were installed at selected locations and field load testing was carried out with a dedicated load testing truck, for different load limits and speeds.

After this instrumentation and testing exercise, a comprehensive Finite Element (FE) based model was created for the steel-concrete composite bridge. Linear static analysis (LSA), Natural frequency analysis (NFA), Linear Transient Dynamics Analysis (LTDA) and Harmonic Response Analysis (HRA) were carried out for different boundary conditions to calibrate the model against field data and to obtain various dynamic responses to test vehicles. Comparative studies have been carried out between the field testing and FE analysis.

This paper catalogues this comparative study and its limitation. It also provides a discussion on theoretical aspects of human perception to vibration and provides an overview of available mitigation methods.