Influence of Welding Stud Arrangement on Shrinkage of Steel-Ultra-High Performance Concrete Composite Bridge Deck

Abstract:

In order to explore the influence of different layouts of welding stud on the shrinkage of steel-ultra-high performance concrete （UHPC） composite bridge slabs， a full-scale segmental composite bridge slab shrinkage monitoring test with a welding stud spacing of 200 mm and 300 mm under normal temperature curing conditions was conducted. Finite element analysis software was used to simulate the shrinkage of the test model. based on which， the parametric analysis of the shrinkage of the composite bridge deck at different welding stud spacing was performed. The test monitoring results show that the initial setting time of UHPC in the test is about 17 hours. The UHPC shrinkage in the edge area of the steel-UHPC composite bridge deck is larger than that in the central area. The maximum shrinkage in the first 72 hours is about 450×10^－6. When the stud spacing increases from 200 mm to 300 mm， the UHPC is weakened by the overall restraint， the restraint effect of the steel plate decreases， and the maximum compressive strain is reduced by about 51.6 %. The restraint effect of the reinforcing steel is strengthened， and the maximum compressive strain value increases by about 42.9 %. The finite element analysis shows that the strain difference at the interface between UHPC and the end of the steel plate increases by 20.9 %， and the shear stress of the welding stud at the maximum slippage increases by 64.7 %. The parametric analysis shows that when the stud spacing increases from 100 mm to 400 mm， the UHPC tensile stress in the mid-span decreases by 3.7 %. The compressive stress of the steel plate in the mid-span decreases by 17.8 %， and the compressive stress of the steel bar increases by 86.3 %. The above results show that the increase of the welding stud spacing weakens the combined effect between steel and UHPC， and at the same time causes the distribution of the secondary internal force of the structure. The secondary internal force between UHPC and the steel structure decreases， the restraining effect of the steel bars increases， and the compressive stress increases. Properly increasing the stud spacing can reduce the UHPC tensile stress and the secondary internal force of the steel structure caused by shrinkage， but it is necessary to pay attention to the weakening of the combined effect on the mechanical properties.