| Fully jointless bridges use the expansion and contraction deformation of the road-bridge link slab instead of the traditional expansion joints of the bridge deck and road-bridge joints to absorb the longitudinal bridge deformation of the main girders,and the road-bridge link slab are in a long-term cracked state,which seriously affects the durability of the structure.In order to improve the stresses in road-bridge link slab,improve their durability and reduce their construction costs,this paper prepared a new low elastic modulus cementitious composite(L-SHCC)by partially replacing fine sand with the rubber powder ground from the secondary processing of waste rubber into the commonly used strain hardening cementitious composites(SHCC).It is used for the fabrication of road-bridge link slab of fully jointless bridges,and the performance of the L-SHCC road-bridge link slab under the combined effect of temperature and vehicle loads is studied to provide theoretical basis for the design of road-bridge link slab of fully jointless bridges.The main contents are as follows:(1)In this paper,15%volume of fine sand in SHCC blended with two lengths(8 mm and 12 mm)of PVA fibers was replaced by rubber powder with a diameter of 80 mesh to make L-SHCC material,and the material properties were tested.The test results showed that the incorporation of rubber powder can effectively improve the tensile properties of SHCC material,but it will reduce its compressive strength.Meanwhile,uniaxial tensile tests showed that the mixing of SHCC material with different lengths of mixed PVA fibers could improve the tensile properties of L-SHCC.(2)Through the longitudinal tensile test and vertical bearing plate test of L-SHCC road-bridge link slab,the force performance and deformation characteristics of road-bridge link slab under the joint action of temperature-vehicle loads were simulated.In the longitudinal tensile test,the L-SHCC road-bridge link slab showed great deformation capacity,with more fine cracks on the slab surface and small crack spacing,and the surface cracks could close by themselves after unloading,indicating that the L-SHCC material has strong ability to absorb deformation.In the vertical bearing plate test,the vertical deformation of L-SHCC road-bridge link slab increases with the increase of vertical load,and the residual deformation after unloading is less than the relevant theoretical calculation of deflection value,which verifies that the road-bridge link slab made of L-SHCC material meets the design strength requirements of pavement.(3)In this paper,the uniaxial tensile stress-strain relationship of L-SHCC material is used to build the L-SHCC bifold intrinsic structure model,and the CDP plastic damage damage criterion of SHCC material is used to establish the finite element analysis model of L-SHCC road-bridge link slab to analyze its force under the joint action of temperature-vehicle load.The structural damage finite element results are obtained.Then the results are compared with the measured results,and the change law is basically consistent,which verifies the correctness of the numerical analysis.(4)The effect of sensitive parameters such as PVA fiber length,plate thickness and substrate resilient modulus on the performance of L-SHCC road-bridge link slab was analyzed by finite element software to obtain the optimal design values of doped fiber length,slab thickness and substrate resilient modulus for the fabrication of L-SHCC road-bridge link slab,which provides a theoretical basis for the design of road-bridge link slab for fully jointless bridge. |
