Flexural stiffness characterization of the corrugated steel–concrete composite structure for tunnel projects

Corrugated steel–concrete (CSC) composite structures are increasingly used in tunnel and culvert projects due to their good mechanical properties. The design of CSC composite structures is often governed by deflection limits in service, hence it becomes crucial to evaluate accurately their flexural stiffness. In this work, the deflection deformation mechanism of CSC composite structure is studied by experimental and numerical methods, and a simplified formula for calculating the flexural stiffness is established. In addition, the deflection results obtained by different methods are compared and analyzed. It is found that: (1) the flexural stiffness of the CSC composite structure is constant only when the load is small, and after the bending moment exceeds a certain value, the flexural stiffness will gradually become smaller as the bending moment increases. (2) The value of the bending moment corresponding to the end of the elastic stage of the bending moment-deflection curve increases with the increase of the axial force in the composite structure. (3) As the axial force of the composite structure increases, the flexural bearing capacity of the structure increases first and then decreases.