Free vibration performance of curved composite box-girders with corrugated steel webs

Abstract The curved composite box girder with corrugated steel webs (CBG with CSWs) shows a more complex performance compared to a straight one due to the coupled flexural-torsional effect caused by its curvature. However, the relevant studies on it were limited. In this paper, considering the shear lag effect of the flanges, the shear deformation of the steel webs, and the coupled flexural-torsional effect, the natural frequencies of the curved CBGs with CSWs were derived using the energy variation method and Hamilton principle. Free vibration experiments were conducted on three simply-supported curved CBGs with CSWs. Numerical analysis was performed using ANSYS software. According to the parametric analysis, the torsional kinetic energy and the additional effect of the restrained torsion have little effect on the natural frequencies in the flexural-torsional vibration, while they significantly affect the flexural mode component. The natural frequencies decrease with the increase of λ (the ratio of calculation span to the radius of the curved axis). When λ ≤ 0.5, the reduction is smaller than 5%, but larger than 10% when λ > 0.7. The span presents an insignificant influence on the fundamental frequency if λ remains constant. Based on the analytical and experimental researches, a simple-to-use equation was proposed to calculate the fundamental frequency of the curved CBGs with CSWs.