Flexural properties of a lightweight hybrid FRP-aluminum modular space truss bridge system

A hybrid FRP-aluminum space truss structure system was designed as a modular emergency bridge with a span of 12 m. The bridge has a light weight of only approximately 1.2 tons and contains 8 structural units, which are composed of an aluminum bridge deck supported by FRP trussed members and connected by male jugs and female jaws based on the pre-tightened teeth connection (PTTC) technique. In the paper, the conceptual design of the bridge, assembly of structural units and bridge erection are described in detail. To understand the actual flexural behavior of the bridge, 4 prototype structural units were fabricated and mounted as a single-span simply supported structure and subjected to the four-point bending loading test. Structural computational models, including two FE models and a simplified analytical planar model, were constructed and validated by the experimental results. The results indicated that (1) the specimen displayed linear behavior under the ultimate-limit-state loading level, and both the strength and stiffness satisfied the design requirements; (2) the bridge deck exhibited an unexpected complex strain distribution, which is different from that of the analogous structure; and (3) the “beam-grillage” FE model and simplified analytical planar model provided effective calculation methods for the proposed bridge.