| In order to improve the performance of reinforced concrete beams by increasing the cross-section method,based on the material test,steel fiber is used as the reinforcing phase of reactive powder concrete,and the performance of reactive powder concrete(RPC)materials under different curing conditions was explored.The main influencing factors are given the optimal steel fiber content and method of RPC.Based on the indoor test,the simple supported test beams strengthened by RPC can be subjected to the indoor static load test,and based on the finite element simulation analysis,the strength law of the simply supported composite beams was studied and explored,and the following research results were obtained:1.Based on the Summarize and analyze the mix ratio in the existing active powder concrete literature,select four factors that have a greater correlation with the strength of the RPC matrix,use different raw materials based on different curing conditions,and use the compressive strength of the matrix as a reference Combined with micro-analysis methods,the optimal reference ratio of reactive powder concrete foundation considering four factors was obtained.2.The copper-plated steel fiber of 12 mm was used as the reinforcement phase of the best basic parameter ratio of RPC.When the steel fiber content increased from 0% to 4%,the tensile and compressive strength of steel fiber reinforced RPC increased with the increase of the fiber content;when the steel fiber content was 5%,the strength began to decline,indicating that the optimal content of 12 mm steel fiber was 4%.Under standard curing,the compressive strength is 123.59 MPa and the tensile strength is 27.6 MPa.Under natural curing,the compressive strength is 113.13 MPa and the tensile strength is 24.67 MPa.Under the combined curing,the compressive strength is 140.14 MPa and the tensile strength is 29.6 MPa.3.The steel fiber RPC with the best volume content was used as the reinforcement material to reinforce the top and bottom of the simply supported beam.Through the indoor static load test,it can be seen that the reinforcement of reinforced concrete beams by the method of superposition is mostly positive,that is,the ultimate bearing capacity of the original beams is increased after the superposition reinforcement.4.The load-deflection curves of composite beams strengthened by ordinary concrete and steel fiber RPC reinforced composite beams are similar to those of ordinary reinforced concrete beams,which have linear elastic stage,crack development stage,nonlinear yield stage and failure stage.Composite reinforcement beam under the circumstance of external load,and a quarter in cross across the distribution of strain along the section height of basic accord with flat section assumption,even in the test beam cracks in composite beams under the action of external force,ordinary concrete with steel fiber RPC also can be a very good work,illustrates the work performance is very good.5.The distribution law of strain and displacement of reinforced composite test beam is obtained by static load test and ANSYS finite element simulation.The structural members of steel fiber RPC based on high compressive and tensile strength cannot meet the requirements of the structural members according to the minimum reinforcement ratio of the current code for reinforced concrete.Therefore,it is necessary to further determine the specifications and dosage of steel bars suitable for reactive powder concrete through experiments.The research results show that the use of steel fiber reinforced RPC materials to strengthen and repair bridge structures can greatly save material consumption,reduce structural size,reduce energy consumption and pollution,and is expected to solve the damage caused by fatigue cracking of existing bridge deck pavements.To a large extent,it can inhibit the further development of cracks and provide certain basic data for the future use of RPC materials for bridge maintenance and repair. |
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