Experiment Analysis on Crack Resistance in Negative Moment Zone of Steel–Concrete Composite Continuous Girder Improved by Interfacial Slip

Abstract

Due to the strong interface effect of continuous steel–concrete composite beams with conventional shear connectors, the efficiency of applying pre-stress in the negative moment zone is greatly reduced, which leads to a difficulty of anti-cracking design in the negative moment zone of pre-stressed steel–concrete composite box girder. In order to study the feasibility and the working mechanism of improving the crack resistance of continuous steel–concrete composite bridges by releasing the interfacial slip effect within the negative bending moment region, two groups of model tests were carried out in the paper. Two steel–concrete composite beams were used for model test, one of them using the conventional stud shear connectors, another one using the new shear connectors, named uplift-restricted and slip-permitted shear connectors. The results show that, compared with the composite beam with conventional shear studs, the composite beams with uplift-restricted and slip-permitted shear connectors have a higher pre-stress application efficiency, and the new connector could release the interface slip, which can make the tensile stress distribution in concrete slab more uniform within the negative moment zone, thus increasing the cracking load of concrete slab and reducing the subsequent crack width effectively. This study is helpful to understand the relationship between the interface slip and the anti-crack characteristics in negative moment zones, and a new anti-crack design method is proposed for the design of continuous composite girder.

Fatigue Experiment Study on Internal Force Redistribution in the Negative Moment Zone of Steel–Concrete Continuous Composite Box Beams

“…Previous studies have shown that the formation of the plastic hinge will cause obvious internal force redistribution at the middle support of continuous composite box beams [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Table 6 shows the measured force (not including self-weight) at the middle support under the target number of loading cycles, with an applied static load of 340 kN.…”

“…Gao et al [ 20 ] carried out fatigue tests on two double-layer composite beams, and the results indicated that the degradation of bond-slip between the concrete and reinforcement in the negative moment zone caused the degradation of stiffness and the development of cracks. Wu et al [ 21 ] studied the feasibility of improving the crack resistance of composite beams by releasing the interfacial slip effect within the negative bending moment zone. Zhang et al [ 22 ] studied the redistribution of the internal force of a steel–concrete composite continuous box beam and found that the influence of the slip at the middle support should be fully considered.…”

Study on the Mechanical Properties of Continuous Composite Beams under Coupled Slip and Creep

“…The stiffness matrix element was obtained via the finite element method, and the slip, torsion and time-varying effects of the composite box girder were simulated [ 18 ]. Through a comparative test of two kinds of bolts, Wu et al studied the slip effect of the negative moment zone of a composite beam to help improve stress distribution and reduce crack width [ 19 ]. M. Valente et al used experimental tests and FE analyses to determine the influences of different shear connection degrees between concrete slabs and steel beams on the seismic responses of composite frames.…”