TEST ON THE STEEL-CONCRETE COMPOSITE GIRDER BY USING SUSPENSION SYSTEM

A new kind of uplift-restricted and slip-permitted T-shape (URSP-T) connector was introduced to decrease the tensile stress of the concrete slab in composite girders subjected to hogging moment. To investigate the performance of a suspension bridge and to study the influence of URSP-T connectors on a composite girder, a three-span composite girder was tested by using a suspension system, and a finite element model was established by ANSYS to analyze test results. The specimen adopted an I-shaped form, and URSP-T connectors were installed at the north side of a specimen to compare with the studs installed at the south side. In the test, the specimen was lifted by the suspension system, and the loading scheme included elastic working conditions, torsional working condition and ultimate working condition. The results showed that URSP-T connectors could decrease the tensile stress of concrete slab effectively. The bending stiffness of a bridge girder was little influenced by URSP-T connectors under normal use stage, but significant interface slip occurred after yield load and the bending stiffness decreased correspondingly. Besides, the torsional stiffness of a bridge girder was also reduced by URSP-T connectors to some extent. The use of URSP-T connectors would increase the compressive stress of a steel girder, and attention should be paid to the buckling behavior of a steel girder in design. To fully release the shear force at a steel-concrete interface, the thickness of foamed plastics should meet the requirement of the maximum interface slippage under normal use stage. The test results also revealed the differences between the supporting system of a suspension bridge and that of a continuous beam. This study can support the subsequent analysis and engineering application of URSP-T connectors, and the test method can provide a reference for the experimental study of suspension bridges.