Experimental study of shear behaviour of concrete-encased non-prismatic girder with CSWs

In a large-span continuous and rigid non-prismatic girder bridge with corrugated steel webs (CSWs), a large shear force is produced at the intermediate supports, which are usually concrete-encased to improve the shear performance of the CSWs. To study the shearing behaviour of a non-prismatic girder bridge with CSWs with concrete encasement (CSWC), experimental and analytical models were investigated. Experimental results show that concrete encasement contributes to the prevention of local buckling in CSWs; moreover, shear stress was found to be reduced by approximately 45% with the help of concrete encasement. The results also reveal that the theoretical ratios of shear force are in good agreement with the experimental results in the elastic stage and that the shear ratio of the CSWs increases rapidly with load, while that of the concrete-encased structures decreases, owing to yielding of the CSWs after cracking of the concrete encasement; the shear ratio of the CSWs then decreases with an increase in load, while that of the concrete-encased structures increases again after the CSWs yield. Finally, a reasonably thick concrete encasement that can effectively resist shear force is recommended, based on the analytical equations examined in this study.