Description
The high durability, low weight and excellent mechanical properties of fiber reinforced polymers are the main reasons for the increasing popularity of composites as a material for pedestrian and bicycle bridges. This was also the case with the widening of an existing Carpathian Bridge in the center of Rzeszów (Poland). This footbridge consists of five single-supported spans of 4.17 + 23.55 + 23.67 + 23.67 + 23.47 m, with the total length of the superstructure 104.95 m, and it is believed to be the longest Polish footbridge made of FRP composites. The spans of the footbridge were created in the form of sandwich panels and each was manufactured in a single infusion process by the VARTM (vacuum-assisted resin transfer molding) method.
Since the footbridge spans are placed on existing pillars and in the immediate vicinity of the city stadium, a decision was made to equip the structure with a durable and reliable SHM monitoring system. The system based on distributed fibre optic sensors (DFOS) was selected and implemented for monitoring. One of the spans was equipped with sensors in the form of SM9 / 125 single-mode fibres in an acrylic coating. The optical fibres of the DFOS system were placed inside the composite structure between the fabrics of the selected laminates, before the infusion process. Thanks to that, the sensors are completely integrated into the material and not exposed to damage or the influence of the environment.
The paper presents the initial system assumptions, the location of the sensors, and the results obtained during the proof load tests performed on the structure before it was open to the public.
