Crack Resistance In The Negative Moment Zone Of A Steel-composite Continuous Girder Bridge And Experimental Study

With the rapid development of the globalization world economy,steel-composite structures are being widely used in the construction of continuous girder bridges at home and abroad for their economic benefits and high construction efficiency.However,the presence of adverse factors such as the concrete deck slab in tension and the steel box girder in compression in the negative moment region can easily cause cracking of the concrete slab.In this paper,a combination of numerical simulation,theoretical analysis and experimental research is carried out to investigate the cracking resistance of steelcomposite continuous girder bridges in the negative moment region and to test the cracking resistance.The main research work includes:(1)A sensitivity analysis based on Midas Civil was carried out on the steelcomposite continuous girder bridge over the South-North Water Diversion Canal.By analysing the effect of different girder drop options on the tensile stresses in the concrete deck slab in the negative moment region,a 50 cm girder drop was selected as the preferred option.Based on the preferred solution,the stresses in the concrete deck slab and steel box girders in the negative moment zone were analysed during the construction and operation phases.(2)A refined force analysis of the deck slab in the negative moment region of a steelcomposite continuous girder bridge is carried out based on the multi-scale finite element method.The combined internal forces at the beam ends in the negative moment region during the construction and normal service phases are calculated and introduced into the local fine model of the steel-composite continuous girder bridge in the negative moment region to form the elastic boundary of the local fine structure.Reduction of the values of tensile stresses in the concrete deck slab in the negative moment region and the range of distribution effects.(3)Six test beams were designed and fabricated to resist cracking in the negative moment region.The effect of different thicknesses of wrapped foam and different spacing of the nails on the stiffness,crack development and deformation capacity of the test beam in the negative moment zone was investigated.The test results show that the concrete slab has the best anti-cracking effect when the nails are wrapped with 5 mm foam rubber and arranged at a spacing of 180 mm.Numerical simulations and parametric analysis of the test beams were carried out by ABAQUS,and a comparison of the tensile damage of the test beam model with the best anti-cracking effect and the test beam model with normal pegs showed that the arrangement of foam adhesive material on the outside of the pegs could effectively improve the crack resistance of the concrete slab in the negative moment region.