A Finite Element Model of a Steel Truss Bridge Validated with Controlled Load Test Data

This work presents the development of a finite element model of a welded railway bridge constructed in 1955. This model will be used as the main tool for a structural health monitoring system of this ageing infrastructure. Such a system requires load monitoring for which the bridge was instrumented with fiber optic Bragg grating sensors spread over two longitudinal and two transverse girders. After the instrumentation, a series of passages using a locomotive with known axle loads and geometry was performed, during which strains were continuously recorded. A comparison between the experimental and numerical results showed excellent agreement for all sensors located remote from the bridge bearings. The comparison also showed that the influence of the bridge bearings on local deformations differs from the hypothesized design, especially at high load. It was found that deformation of structural elements is strongly constrained to the loaded sectors. The truss design efficiently transfers the loads on the longitudinal girders through the closest transverse girders onto the main trusses.