Design And Performance Study Of PVA-ECC Bridge Deck Link Slab

As an important component of the bridge structure,the expansion device is subjected to the repeated impact of vehicle load and environmental changes,which is easy to cause damage and increase the burden of maintenance work.Without changing the structure of the entire bridge,the bridge deck link slab is used to connect the adjacent simply supported beams to form a jointless bridge deck,which is named as "the best expansion joint is no expansion joint".It is promised to solve the problem of water seepage in the expansion joint position and enhance the stability and durability of the bridge deck with good social benefits.(1)In this paper,Polyvinyl Alcohol-Engineered Cementitious Composite(PVA-ECC)with good performance is selected for the bridge deck.The research is carried out from four aspects,including PVA-ECC orthogonal experimental design and its mechanical properties test,stress analysis and theoretical calculation of bridge deck link slab,scale test and finite element numerical simulation.The main research contents and conclusions of the thesis are as follows:(2)The PVA-ECC orthogonal experimental design was carried out with four factors and three levels.A series of experiments were carried out to study the influence of the factors of water-to-binder ratio,water reducer,fly ash and fiber content on the compressive,tensile and bending properties of the PVA-ECC properties,where cubic,dumbbell and thin plates were pabricated for compression,tension and bending at different ages(7d,14d,28d),respectively.Through the method of range and variance analysis,the influencing factors on the test significance were qualitatively and quantitatively calculated,and then the optimal level is obtained for the optimal combination.The results show that the water-to-binder ratio and water reducer significantly affect the compressive strength.When the volume of 2%fiber is used,the tensile specimen can achieve 2.5%tensile strain,the displacement of the thin plate can reach 15mm,and the crack develops dense and uniform.(3)Based on linear elastic analysis method,the mechanical analysis of the bridge deck link slab were calculated under the action of load,thermal action,concrete shrinkage and creep.Moreover,the detailed construction measures were optimized.It is indicated that the length of the bridge deck link slab and debond zone is related to the actual amount of expansion of the main girder,and the recommended length is 7.5%and 4%-5%of the total length of the connected bridge.(4)The bridge deck link slab scale models were investigated,under the coupling of static load and thermal action,data of the load-displacement,key part strain and rotation angle of the link slab were collected.The test results show that the peak load of the link slab drops significantly under temperature coupling,and the falling range is 7.5%-66.4%.The link slab with the CFRP plate exhabits excellent performance.The strain of the bottom plate and the debond zone develops rapidly up to 10000με,where the excellent performance of PVA-ECC is fully achieved.The experimental models were established with finite element software ABAQUS.According to the design parameters of the test components,the nonlinear analysis was carried out.Under the coupling of static load and thermal action,the effects of different reinforcements on the performance of the link slab were simulated.The results show that the finite element calculation results are in good agreement with the experimental results,and can accurately simulate the stress process of the test members.It is revealed that this model can be used for the further study.