Study on Dynamic Characteristics of Light-Weight FRP Footbridge

Comparing to footbridges made of traditional materials, FRP (fiber reinforced polymer) footbridges have many advantages, such as rapid installation, corrosion resistance, waterproof property, pleased appearance, lasting color, overloading resistance, good fatigue performance, good seismic performance, and potential capacity to build greater span. A tentative FRP cable-stayed bridge is investigated, in which the design method and the design indices for FRP footbridges are studied. It is found that the vibration comfort of FRP footbridge are the main controlling factors for structural design. The indices for the pedestrian vibration comfort requirements are also summarized, and the frequency limit, acceleration limit and excitation load are analyzed. Considering the finite element analysis and the field measurement results, it is concluded that the acceleration should be the controlling indicator, and a simplified excitation load model and the calculation method for acceleration are proposed. For the cable-stayed FRP footbridge, the results of finite element analysis and field measurement show that it can’t meet the designing requirements. Hence, the improvement of overlaying a concrete layer is proposed. After it, the behaviors of the FRP footbridge meet the requirements. All these works make out the design approach and the design indices for FRP footbridges, which are proved practical and reasonable through the actual FRP footbridge.