The Mechelen footbridge in Belgium is a steel structure with a curved alignment in plan and an overall length of approximately 53 m. Its box girder, with a total width of 5 m, includes a 0.50 m bench and a 4.50 m traffic lane. It is composed of welded steel plates. Its external depth varies: it is minimal at the abutments and reaches its maximum value at mid-span. The footbridge is supported by a steel pier that divides it into two spans.

The behaviour of the footbridge is analysed numerically using two models.

First, a non-linear shell model is used to study the behaviour of the structure from the erection phase through to its ultimate capacity. Developed using ANSYS software, this model accounts for geometric imperfections as well as geometric and material non-linearities. The behaviour of the footbridge is assessed at the ultimate limit state, after which the traffic loads are progressively increased to evaluate the structural reserve strength and ultimate capacity.

At the same time, a linear elastic beam model is used to analyse the overall behaviour of the footbridge under serviceability, ultimate limit state and accidental load combinations required by the applicable standards. This analysis also provides a framework for validating the results obtained from the non-linear model.

A dynamic analysis is also carried out. The natural frequencies of the footbridge are determined and the vibration comfort level is assessed. A tuned mass damper is then designed, and the calculations demonstrate that this equipment improves the dynamic behaviour of the structure while increasing pedestrian comfort.