Load-bearing performance of a lightweight emergency bridge assembled by GFRP rectangular tubes with novel prestressed cable system

Emergency bridges are crucial to providing emergency relief supplies to those isolated residents affected by natural disasters. To increase the bridge's load-bearing capacity and adaptability for different obstacles in military or natural disaster relief, a novel Bi-Plane V (BPV) shaped prestressed unbonded retrofit cable system was applied to reinforce an emergency bridge assembled using glass fiber-reinforced polymer (GFRP) rectangular tubes and steel components. The reinforcing system can prestress steel wire cables by adjusting the length of the vertical brace without using a hydraulic jack or any surface preparation. A pre-tightened teeth connection (PTTC) was efficaciously devised for fastening pultruded GFRP rectangular tubes and steel sleeves. All the parts including the prestressed system and bridge modules can be assembled and disassembled rapidly through single lug and yoke plate joints. Bending tests were conducted to investigate the structural responses under three different conditions. Results demonstrated that the novel prestressed cable system enhanced the overall stiffness of the bridge, improving the mechanical performance and stress state of the GFRP tubes in bridge modules. The dynamic parameter identification test results indicated that by applying about 9.85kN cable force in each trackway, the first-order natural vibration frequency increased about 37.5%. Vehicle-through load test results showed that the bridge had the bearing capacity of medium-sized cars, and the corresponding impact factors at about 5 km/h are within the limit of the code.