Search

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. [ABSTRACT FROM AUTHOR]

• Web shear buckling of composite girders in negative-moment regions is studied. • A 3D nonlinear finite element prediction model is developed and validated. • Top flange and slab together provide fixed boundary condition on one edge for web. • A new formula for web shear-buckling coefficients of composite girders is proposed. Steel–concrete composite girder webs used to connect flanges in bridges are generally slender, which introduces stability problems. The assumption in existing codes that the web is simply supported on four sides is excessively conservative and unreasonable. In this study, web shear buckling of steel–concrete composite girders in negative-moment regions were experimentally and numerically investigated. The failure modes, shear-buckling loads, and ultimate loads of the specimens were analysed. Based on the surface strain and out-of-plane deflection of the web, the web shear-buckling load was determined and compared with the theoretical results. A three-dimensional non-linear finite element model is developed and validated based on the experimental results. Using the validated numerical model, the elastic shear-buckling behaviour of the webs of composite girders under actual boundary conditions were investigated. The numerical results showed that the boundary conditions of the composite girder web can be regarded as simply supported on two opposite edges, fixed on one edge, and restrained by the bottom flange on one edge. A formula for calculating the web shear-buckling coefficient of composite girders was proposed based on the numerical results. [ABSTRACT FROM AUTHOR]

Existing studies on the behaviour of steel–concrete composite girders under combined bending and shear are mainly focused only on composite beams with compact sections; very few studies have investigated slender composite girders, which are commonly used in bridge engineering. Therefore, the behaviour of slender steel–concrete composite girders under combined negative moment and shear were investigated experimentally and numerically in this paper. With the moment/shear ratio, reinforcement ratio, connection type, and web thickness as the experimental parameters, experiments were conducted on seven simply supported composite girders subjected to negative moment and shear. The test results showed that reinforcement ratio, concrete slab thickness, and web thickness significantly influence the ultimate load and failure modes of composite girders; the connection type only slightly influences the behaviour of full-shear-connection composite girders under combined negative moment–shear interaction. All the test data were outside the moment–shear interaction curve of Eurocode 4, i.e. Eurocode 4 tended to produce safer results. Then, a nonlinear finite element model was developed and validated using the experimental results. The factors affecting the moment–shear interaction of composite girders in negative-moment zones were studied through numerical simulation. The numerical results showed that the negative moment–shear interaction law changes little with the change of reinforcement ratio or slab thickness. The web depth-to-thickness ratio significantly influences the negative moment–shear interaction law, and the higher the web depth-to-thickness ratio, the earlier the composite girder begin experiencing moment–shear interaction. Unlabelled Image • Behaviour of slender steel-concrete composite girders under moment–shear is studied. • Composite girders with different experimental parameters were tested • A finite element (FE) prediction model is developed and validated. • Slab & web thicknesses greatly affect composite girder capacity and failure mode. • Web depth–thickness ratio greatly affects composite girder moment–shear interaction. [ABSTRACT FROM AUTHOR]

• Vertical shear behaviour of steel–concrete composite girders under negative moment. • Non-compact sections are considered. • A nonlinear finite element model was developed and verified using tests results. • The shear distribution of the cross-section in the load process was investigated. • Concrete slab contributes greatly to the shear capacity of non-compact girders. To investigate the vertical shear performance of steel–concrete composite girders commonly used in bridge engineering, experimental tests were conducted on five simply supported composite girders and one bare steel girder under negative moments. The main test parameters were depth and reinforcement ratio of concrete slab, connection type, and web thickness. The test results showed that the ultimate load of the composite girder increased by 10–20% compared with that of the bare steel girder. When the concrete slab thickness increased from 115 mm to 180 mm, the reinforcement ratio was doubled, web thickness increased from 6 mm to 8 mm, the shear capacity of the composite girders increased by 9.1%, 4.4%, and 49%, respectively. The specimen with Perfobond rib connectors exhibited comparatively better ductility. Compared with the results obtained with the current AASHTO and EC4 codes, the shear capacity increased by 8–16% and 5.8% for composite girders with web thicknesses of 6 mm and 8 mm, respectively. A nonlinear finite element model was developed and verified using the test results. Using the validated numerical model, the shear distribution of the cross-section was investigated and parametric analyses were conducted. The shear distribution of the section was divided into four stages, namely elastic, slab cracking, steady, and web buckling stages, during the entire loading procedure. Parameter analysis showed that the slab thickness significantly influences the shear capacity of the composite girder. With increasing web depth–thickness ratio, the contribution of the concrete slab to the shear capacity increases. [ABSTRACT FROM AUTHOR]

The static mechanical properties of grouped-stud shear connectors in steel–ultra-high-performance concrete (UHPC) composite beams are rarely investigated. In this study, the static mechanical properties of grouped-stud shear connectors in steel–UHPC composite beams are investigated via experiments and numerical simulations. Seven sets (14 specimens) of push-out tests are conducted by varying the parameters, including the concrete type, stud diameter, stud vertical spacing, and number of stud rows. The test results show that the shear bearing capacity of grouped-stud shear connectors increases by 27.5% as the stud diameter increases from 19 to 22 mm, by 13.2% compared with that of grouped-stud shear connectors in steel–UHPC and steel–normal concrete (NC), and by 5.8% when the stud vertical spacing increases from 125 mm (5.68 d) to 200 mm (9.09 d). However, the shear bearing capacity of the grouped-stud shear connectors remain almost unchanged when the number of stud rows is changed from two to four. The effects of stud diameter, stud tensile strength, stud vertical spacing, stud length, the cover thickness of the stud head, and stud transverse spacing on the shear bearing capacity of the grouped-stud shear connectors are investigated via numerical simulations. The results show that the stud diameter, stud tensile strength, and stud vertical spacing significantly affect the shear bearing capacity of the grouped-stud shear connectors, whereas the stud length, the cover thickness of the stud head, and stud transverse spacing exert almost no effect. Based on experimental and numerical analyses, an equation for predicting the shear bearing capacity of grouped-stud shear connectors in steel–UHPC is proposed and validated based on experimental and numerical results. • The static mechanical properties of grouped-stud shear connectors in steel–UHPC composite beams are investigated. • A nonlinear finite element model was developed and verified using tests results. • The Shear carrying capacity of the grouped-stud shear connectors in steel–UHPC is evaluated using current codes. • A formula for predicting the shear bearing capacity of grouped-stud shear connectors in steel–UHPC is proposed and validated based on experimental and numerical results. [ABSTRACT FROM AUTHOR]