Dynamic response under pedestrian load of a GFRP–SFRSCC hybrid footbridge prototype: Experimental tests and numerical simulation

The use of glass fibre reinforced polymer (GFRP) pultruded profiles in civil engineering structures has known considerable growth in recent years due to their high strength, low self-weight and corrosion resistance when compared to traditional materials. However, the high deformability, the susceptibility to instability phenomena and the brittle failure are delaying the widespread use of this structural material. GFRP–concrete hybrid systems have been proposed as an alternative to fully composite structures in order to overcome some of those drawbacks, namely the deformability and instability problems. These hybrid solutions are especially attractive for footbridge structures whose design is often governed by serviceability requirements. Nevertheless, in order to make these structural systems standard solutions for civil engineering practice it is necessary to gather in-depth understanding about their structural behaviour, namely under dynamic loads, and to assess the ability of current design tools to predict their response. This paper presents experimental and numerical investigations concerning the dynamic behaviour under pedestrian induced loads of a 6.0 m long hybrid footbridge prototype comprising two GFRP pultruded profiles and a thin steel fibre reinforced self-compacting concrete (SFRSCC) deck. The results of dynamic tests and respective numerical simulations are compared in order to access the ability of conventional finite element (FE) models to predict the structural response of the hybrid footbridge, namely the accelerations as a function of time for different types of pedestrian loads. The experimental data are also compared with regulation requirements concerning human comfort. The results obtained show that the models developed using conventional numerical tools are able to predict the dynamic response of the footbridge prototype under pedestrian actions with fairly good accuracy. The comparison of the results with regulation requirements also attests the feasibility of the hybrid structural solution proposed.