Study On Fatigue Performance Of Hybrid Fiber Reinforced Concrete Bridge Slabs

With the increasing traffic volume,the deck slab of the combined girder bridge is especially damaged under the action of wheels,which causes the service life of the deck slab to be greatly shortened.Recent studies have shown that hybrid fiber reinforced concrete(HFRC)has the advantages of good crack resistance and durability,high stiffness,and impact resistance,etc.,which can be concerned by the industry.This paper attempts to introduce it into the composite girder bridge deck slab,and study its fatigue performance through the fatigue test of hybrid fiber HFRC deck slab,with the focus on the following research:(1)Two bridge deck slabs(one plain concrete deck slab and one HFRC deck slab)were fabricated for fatigue testing to investigate the key indicators such as reinforcement strain,concrete strain,dynamic deflection,crack change and residual bearing capacity.The results showed that when the fatigue times accumulated,the strains of reinforcement and concrete as well as the deflection of the slab increased,and the crack width of the bridge deck gradually increased,and the residual bearing capacity of the ordinary concrete deck decreased by about27.18% and that of the HFRC deck decreased by about 21.37% after the fatigue accumulated to 2 million times;compared with the ordinary concrete deck,the strain of the reinforcement of the HFRC deck decreased by Compared with the ordinary concrete deck slab,the strain of HFRC deck reinforcement decreased by 10.84%,the strain of concrete decreased by 11.52%,the deflection of the deck slab decreased by 14.31%,and the maximum crack width of the slab was reduced by 8.61%;because the dynamic deflection of the deck slab was in the elastic stage during the fatigue test,the change was not obvious.(2)Based on the fatigue test,the HFRC deck slab was applied to the actual bridge to study the effect of HFRC on the fatigue performance improvement of the deck slab.Firstly,a typical combination bridge in service was selected,and a finite element model of the bridge deck was established using ABAQUS software and its accuracy was verified,then the finite element analysis results were imported into FE-SAFE program for fatigue analysis and compared with the mature fatigue formula,and the two were in good agreement.the fatigue life of the bridge deck increases.(3)According to the fatigue test of the bridge deck and the numerical simulation results of the actual bridge,the fatigue formula of the single fiber reinforced bridge deck is improved,and the fatigue deflection formula,fatigue stiffness formula and fatigue crack width formula of HFRC bridge deck are proposed,which can provide reference for the fatigue design of HFRC bridge deck;the calculation results from the improved fatigue formula show that the fiber incorporation increases the stiffness of the bridge deck and improves the fatigue and crack resistance of the bridge deck.Crack resistance.