Experimental research on curved continuous steel-concrete composite twin I-girder bridge

Due to the excellent economy and convenient erection, curved continuous steel–concrete composite twin I-girder (CTIG) bridges have been applied in mountainous bridges and unban overpasses. Rigorous investigation of the bending-torsion interaction is important for the curved continuous CTIG bridge design. A CTIG model bridge with a span arrangement of 17.46 m + 17.46 m and a curved radius of 200 m, was fabricated and tested under a symmetric static load. The mechanical behavior and failure modes of the model bridge were investigated. Results show that the non-uniform torsion and the web distortion effect are the characteristic mechanical behaviours of the curved CTIG bridge. The crossbeams resist the web distortion to ensure the transmission of the torsional moment. The constraint of the web distortion by the crossbeams results in the bottom flanges of the CTIG bridge being subjected to additional lateral bending moments. The ultimate strength of the CTIG bridge studied in this research is reached by a shear failure involving web buckling, formation of diagonal web yielding, and concrete deck crushing. This study contributes to a deeper understanding of the mechanical behavior of the curved continuous CTIG bridge and provides a valuable experimental basis for research regarding the design of bridges of this type.