Time-dependent Composite Effect of the Curved Steel-concrete Composite Beams in Construction Stage

Abstract

In order to accurately analyze the mechanical behavior of the steel-concrete composite beams in construction stage, firstly the change law of the shear strength of the stud connectors with the concrete age was studied using the push-out test, in which the time-dependent shear strength formula of the stud connectors was obtained. Secondly, model tests of two simply-supported curved composite beams were carried out during the casting process of concrete slab, the ANSYS finite element models were build with the time-dependent shear strength formula applied in it, and then the experimental and numerical results were verified for each other. On the above basis, a three-span curved continuous composite beam bridge was taken as the sample, by which the influence of the stud connector’s timedependent shear connector strength on the stress behaviors of composite beam in construction stage was studied. The analysis results indicate that the shear strength and stiffness of stud connectors cannot be ignored even when the concrete is in rather early stage, and the early shear strength increases more quickly, whereas the later shear strength slowly. During the segmental casting process of concrete slab, if the casting time interval is between 6 hours and 7 days, the time-dependent characteristics of the early composite action should be considered in the stress behaviors analysis of composite beam in construction stage. Meanwhile, for the hardened concrete segment, the relative slip between the steel girder and concrete slab should also be considered, or else unsafe calculation results will be induced.