Experimental Investigation of the Shear Behavior of Slender Continuous Steel-Concrete Composite Girders in Hogging Moment

Predicting the shear strength of composite girders is critical in improving the efficiency of bridge engineering. To investigate the shear behavior of slender continuous steel-concrete composite girders commonly employed in bridge structures in hogging moment regions, experiments were conducted on three slender two-span continuous composite girders with the moment/shear ratio of the section at the interior support as the test parameter. The test results showed that all three continuous girders experienced web shear buckling and shear failure of the concrete slabs. As the moment/shear ratio increased from 0.59 to 0.89, the shear strength decreased by 12.5%. The shear strengths of the specimens were evaluated using the design methods in the existing AASHTO and Eurocode 4 codes, as well as the one proposed by Liang et al. They were 21%-38% and 33%-50% higher than those calculated by the existing AASHTO and EC4 codes, respectively, indicating that the two codes yielded very conservative results. A numerical study was conducted using the nonlinear finite element model validated by the test results. The results showed that the moment/shear ratio, concrete slab thickness, and web height-to-thickness ratio all significantly influence the shear strength; the codes will yield increasingly conservative predictions with the increase of concrete slab thickness or web height-to-thickness ratio. Both test and numerical results revealed that the design method proposed by Liang et al. can better predict the shear strength of continuous composite girders in hogging moment regions.