Mechanical behavior of concrete-filled rectangular steel tubular composite truss bridge in the negative moment region

Concrete-filled rectangular steel tubular (CFRST) composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab. This new type of bridge has the advantages of high structural force-transferring efficiency, rapid assembly construction speed and excellent total life cycle, which meets the construction concept of green, recyclable and sustainable development. Due to the broad application prospects, experiment on the flexural behavior of CFRST composite truss bridge in the negative moment region was reported by authors previously. This paper thus presents a finite element analysis (FEA) modelling verified by the reported test data to further investigate the detailed analytical behavior of this structure. The structural response and failure mechanism of CFRST composite truss beam in the negative moment region are studied. In addition, the important structural design parameters on the flexural performance of the CFRST composite truss beam are also investigated, including the height to span ratio, the brace-to-chord wall thickness ratio, the reinforcement ratio of steel reinforcements and prestressed tendons and the strength grade of concrete infill in chords. Finally, the reasonable structural design parameters range are proposed for the optimum design of the CFRST composite truss bridge.