Abstract
Fibre reinforced polymers (FRP) are gaining momentum in bridge engineering applications, particularly where lower weight and ease of installation are important factors. Due to their reduced weight, special attention needs to be paid to dynamic behaviour and the human-structure interaction. This research investigates the vibration performance of a recently constructed FRP suspension footbridge. Initially, the bridge was analysed using FE modelling, followed by field testing which provided measurements for the frequencies, mode shapes and damping, as well as for the dynamic response induced by pedestrians. The experimental modal data were subsequently used to calibrate the FE models. The results provided information about the vibration characteristics of such bridges and better understanding regarding specific FE modelling aspects. Subsequently, this research investigated how damage affects the vibration characteristics of FRP bridges and whether it is possible to identify its location. Two GFRP beams were progressively bonded using strap joints to simulate gradual degradation of the joints. Damage assessment was carried out through specialised damage identification techniques (DIT) that utilise modal data. In addition, the calibrated FE bridge models were used to undertake a damage assessment of the structure. Several possible damage scenarios that cannot be identified by visual inspection were simulated numerically. The results showed that only certain types of damage can have a significant effect on the structure’s modal properties. However, the application of DIT was generally successful in identifying the presence and in most cases the location of damage.