Experimental research on free vibration of curved composite box-girders with corrugated steel webs

The curved composite box-girders (CBGs) with corrugated steel webs (CSWs) have been used widely in bridges due to their great advantages and the demand of the road alignment, but the curvature makes both the static and dynamic behaviors more complex. To research the free vibration performance of the curved CBGs with CSWs, 5 simply-supported test girders were designed with the span-to-radius ratio (n=L/R), the number of the cells of the box section, and the number of the diaphragms as parameters. The natural frequencies and mode shapes were measured in the experiment. The experimental results were compared with the numerical results using ANSYS software, and a satisfying agreement was obtained. The parametric analysis shows that for the curved CBG with CSWs, the vertical mode shapes are combined flexural and torsion, and the contribution of the torsional effects to the mode shapes and frequencies improve with the increase of n, which leads to a decrease in the vertical and lateral frequencies and increase in the torsional frequency. The corrugated angle of the steel web has little effect on the natural frequencies of the curved CBGs with CSWs. Increasing the thickness of the steel web and the number of the diaphragms can improve the torsional rigidity of the curved CBG with CSWs effectively; while the deck width has a great contribution on the lateral rigidity.