| Factors such as the axial expansion and contraction of the beam,the rotation of the beam end,and the vertical inconsistent deformation between the adjacent two spans will cause the continuous structure of the bridge deck to undergo large bending and tensile deformation at the joint.At the same time,the stiffness and strength of continuous structure of the bridge deck are weak compared to the overall structure of the bridge span.Therefore,the continuous structure of the bridge deck is prone to cracks.Steel fiber fine aggregate concrete is a composite material obtained by adding appropriate amount of short steel fibers into the concrete matrix,and has the characteristics of high strength and good toughness.In this paper,the steel fiber fine aggregate concrete is used to locally reinforce the continuous structure of the bridge deck at the joints,and corresponding researches are carried out.The main work and results are as follows(1)Based on the preliminary research results,the orthogonal method is used to optimize the design of a group of self-compacting steel fiber fine aggregate concrete with a strength of about 60 MPa and good fluidity.This paper studies the influence of cement dosage,fly ash replacement rate,sand rate and steel fiber volume ratio on the compressive strength,split tensile strength and four-point bending strength of SFRC-FA.And the comprehensive balance method is used to determine the optimal mix ratio:cement content is 470kg/m^3,fly ash replacement rate is 25%,steel fiber volume rate is 1.8%,sand rate is 55%.Analysing the destruction mechanism of fiber fine aggregate concrete by combining with SEM and X-CT technology.At the same time,in the preparation process of SFRC-FA,the effect of stirring time on the state of the mixture is explored The steel fiber fine aggregate concrete finally obtained is used in actual engineering and bridge deck slab test specimens(2)At the same time,this paper replaces the ordinary concrete at the joints of the bridge deck with steel fiber concrete for local reinforcement,and discusses the effect of the width of the steel fiber concrete replacement area and reinforcement ratio on the mechanical properties of the bridge deck.Three-point bending static tests are carried out on 9 groups of different types of steel fiber reinforced concrete bridge deck continuous specimens,Comparing and analyzing the failure characteristics and crack development,neutral axis,load-deflection relationship,strain of steel bar,etc of the specimens,combined with ABAQUS.It is concluded that an optimal design scheme that can appropriately reduce the reinforcement ratio and the width of the steel fiber concrete replacement area is 500 mm has a certain effect on improving the mechanical properties of the bridge deck continuous slab.(3)Based on the results of the three-point bending static test,Four-point bending static tests are carried out on 10 groups of different types of steel fiber reinforced concrete bridge deck continuous specimens and 3 groups of ordinary concrete bridge deck continuous specimens.By comparing and analyzing the failure characteristics,crack development,neutral axis,load-displacement relationship,bearing capacity,stiffness and ductility of the specimens,this paper explores the effect of the width of the steel fiber fine aggregate concrete replacement area and reinforcement ratio on the mechanical properties of the continuous deck.It is found that the use of steel fiber fine aggregate concrete to locally reinforce the continuous deck slab significantly improves the flexural bearing capacity,stiffness and ductility of the bridge deck specimens,delays the cracking of the specimens,and also slows the rise of the neutral axis of the section,effectively improves the collaborative deformation ability of the specimens.The change of the reinforcement ratio is positively correlated with the change of the bearing capacity,stiffness and cracking load of the specimen,but negatively correlated with the change of the ductility of the specimens. |
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