Improving fail-safety of road bridges built with non-ductile fibre composites

Fibre composites are excellent materials for the construction of bridge decks since they are lightweight, show high corrosion resistance and can be pre-fabricated. The bridge deck investigated in this paper is composed of prismatic bars made of glass fibre-reinforced polymer (GFRP). The hollow sections are continuously produced by ‘pultrusion’ and adhesively bonded together in order to achieve an aerial bridge deck. ittle failure modes of fibre composite materials leads to low material utilisation when designing structural members. For other applications, the low elastic modulus of glass fibre composites compared to steel is also limiting the material utilisation. However this is no decisive design aspect for FRP bridge decks. Several structural details of fibre composite road bridges are scrutinised regarding their failure mode and optimised solutions are developed. Due to the thin walls, the impact of concentrated wheel loads on the deck is a critical load case. Moreover, accidental loads such as errant trucks need to be retained by ductile failure mechanisms. additional means of improving fail-safety, a structurally integrated sensor network is being developed which is capable of allowing in part for the safety deficits of the brittle material. The sensors allow for online monitoring and early detection of damages. Due to the integration, the sensors are protected against harsh weather conditions or mechanical damage. Fibre optic sensors have been chosen since they are durable, easy to embed and mean only minor influence to the laminate. The complex sensor-lamina-interaction is being analysed in order to predict measurement results and optimise the sensor layout. Moreover, procedural problems had to be solved like the fibre placement and coupling after the sensor fibre has been embedded. The specimen shows very good accordance to mechanical prognosis and allow for a smart FRP girder which underpins the new concept.