| Our country’s infrastructure construction is in full swing,concrete engineering quantity of the highest in the world,but with the increase of use fixed number of year,ordinary concrete structure in complex service environment to produce different degree of cracking aging,resulting in a decline in the bearing capacity of the whole structure caused the huge maintenance costs and environmental stress.There is an urgent need for a new type of high performance concrete to replace ordinary concrete,and PVA fiber cement matrix composite material has the high compressive strength and high splitting tensile strength that traditional concrete does not have,as well as the durability and bending toughness of the repair material to improve the beam structure.This paper aims to study the compressive strength,flexural strength and bending toughness of PVA fiber cement-based composite beams respectively through field tests and 3D numerical simulation with ANSYS finite element software.The main research contents and relevant conclusions are as follows:(1)Respectively by pressure testing machine for 15 groups of different dosage of PVA fiber cement-based composite materials of cube compressive strength test,found that the addition of PVA fiber in a certain range can improve compressive strength of block,but its compressive strength with the increase of PVA fiber volume content and is not improved,relations between the parabolic trend;At the time V_f=1.0%,the cube had the highest compressive strength,about 10 percent higher.(2)the flexural properties of 15 groups of trabecular specimens of PVA fiber cement matrix composite with a size of 40mm×40mm×160mm were tested,and the effects of PVA fiber content and curing age on the flexural strength of PVA fiber composite were studied respectively.The results show that the addition of PVA fiber can obviously change the failure mode of cement matrix composites in the flexural strength test.With the increase of PVA fiber content,the flexural strength of the specimen was improved.With the increase of curing age,the flexural strength of the specimen also gets a small increase.The fiber content has more influence on the flexural strength of the specimen.(3)the fifty four group 100㎜×100㎜×400㎜composite beam specimen of a four-point bending test,the strength of concrete,composite beam bonded surface treatment method and PVA fiber cement based composite material layer thickness on the properties of PVA reinforced concrete composite beam bending,and analyzes the specimen failure process and bending performance.The results show that the ultimate load of the composite beam increases by 26.7%~48.4%with the increase of PVA fiber cement matrix composite material layer thickness compared with the ordinary concrete beam with matrix strength C30.Compared with ordinary beams with matrix strength C40,the ultimate load of composite beams increases by 15.7%~46.6%with the increase of PVA fiber concrete layer thickness.With the increase of the strength grade of concrete matrix,the ultimate bearing capacity of composite beam is obviously increased.The ultimate load of composite beam bond surface is improved by gouging treatment.(4)Using ANSYS finite element analysis software,the bending performance of PVA fiber composite beam composed of 100mm×100mm×400mm PVA fiber composite material and ordinary concrete is numerically simulated,which mainly includes:determination of constitutive relation of material,boundary and constraint conditions,stress analysis.The conclusions are drawn as follows:the load-deflection curves obtained by numerical simulation of each specimen have a higher degree of agreement with those obtained by the test,but the test curves are more full.By comparing the simulated value of ultimate load of PVA fiber cement composite beam with the test value,the error range is 3.81%~13.17%,which indicates that the ANSYS analysis results are close to the test value,indicating that the numerical simulation method is feasible on the whole and has reference value. |
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