Experimental research of bending capacity for steel and concrete composite girder with concrete filled tub

In order to study the bending capacity of steel and concrete composite girder with concrete filled tubular up-flange (SCCGCFTF) under static load, a static test for SCCGCFTF was performed, a finite element model of SCCGCFTF was established by using ANSYS, nonlinear static parameter analysis was presented, and a formula for the ultimate bearing capacity of normal section was proposed based on perfected elastic-plastic model for steel and restricted concrete model for inner concrete. Analysis result shows that the strain distribution of the girder agrees well with the assumption of plan section, its bending ultimate bearing capacity and ductility are high, and no skip was found between inner concrete and steel tube. The bending ultimate bearing capacity of SCCGCFTF increases with the increases of the ratio and yielding strength of steel. With the strength enhancement of inner concrete, the bending capacity does not increase obviously, but the ductility of steel can be utilized adequately. So the relationship between the yielding strength of steel and the strength of inner concrete should be adjusted according to design requirements. The ratio of experimental ultimate flexural bearing capacity to its calculated value was 1.07, therefore, the theoretical formula for calculating the bearing capacity is relatively safe.