Finite Element Analysi On Behavior Of RC Beams Strengthened With High-strength Steel Stranded Wire Mesh And ECC

Due to its high tensile strength and easy transportation,high-strength steel strands are currently widely used in combination with polymer mortar to strengthen reinforced concrete structures.However,the polymer mortar is easy to crack,which will cause secondary damage to the components in the external environment and affect the durability of the structure.ECC（engineering cementitious composites）is a kind of fiber-reinforced cementitious composites designed by system micromechanics and exhibiting high ductility under tensile and shear loads.It has the characteristics of multi-slit cracking and pseudo-strain hardening.In order to more effectively improve the durability,safety and sustainability of RC beams after flexural reinforcement,and to give full play to the good mechanical properties and characteristics of ECC materials,a combination of ECC and high-strength steel wire mesh is formed.The special performance of ECC can effectively prevent large-area cracks.Therefore,the use of ECC to replace the polymer mortar in the high-strength steel wire mesh-polymer mortar can make up for the shortcomings of the polymer mortar and maximize the advantages of high-strength steel wire and ECC.Due to the high cost and limited number of tests,it is necessary to conduct indepth research on the flexural performance of high-strength steel wire mesh-ECC flexuralstrengthened RC beams through finite element simulation to provide a theoretical basis for engineering applications.This paper proposes a finite element modeling method for RC beams strengthened by highstrength steel wire mesh-ECC flexural strength,and compared with the test in bending momentdeflection curve,ultimate load value,yield strength to verify the correctness of the model.After confirming the feasibility of the finite element modeling method,parameter analysis of concrete strength,longitudinal reinforcement ratio,steel strand reinforcement ratio,steel strand ultimate tensile strength,steel strand elastic modulus,ECC ultimate tensile strength,ECC initial cracking strength,ECC ultimate tensile strain,pre-stress level,load-holding level and the effect of creep on reinforced beams.Finally,combined with theoretical derivation,the calculation formulas for yield strength and ultimate bearing capacity of reinforced concrete beams with high-strength steel wire mesh-ECC flexural strengthening are proposed.The conclusions reached are as follows:（1）The modeling method in this article is used to compare with the experiments in the existing literature.The experimental results and the simulation results obtained are the three characteristic values of yield strength,ultimate strength and mid-span deflection when the steel strand is broken.The average errors are 9.58%,3.21% and 8.35% respectively,and the bending moment-deflection curve obtained by the simulation calculation is in good agreement with the test curve,which shows the correctness of the finite element model.（2）In terms of bearing capacity,the parameters that have a significant impact on the yield strength of reinforced members are longitudinal reinforcement ratio,steel strand reinforcement ratio,steel strand elastic modulus,pre-stress level and load-holding level.The yield strength of the component is positively correlated with the reinforcement ratio of the steel strand,the elastic modulus of the steel strand,the prestress level,and the ratio of longitudinal reinforcement;it is negatively correlated with the load-holding level.The parameters that have a significant impact on the ultimate strength of reinforcement members are concrete strength,longitudinal reinforcement ratio,steel strand reinforcement rate,and steel strand ultimate tensile strength.The ultimate strength of the member is positively correlated with the reinforcement rate of the steel strand,the ultimate tensile strength of the steel strand,the strength of the concrete,and the ratio of longitudinal reinforcement.The pre-stress level and load-holding level have little effect on the ultimate strength.（3）In terms of deformability,the parameters that have a significant impact on the ultimate deflection of reinforced members are concrete strength,longitudinal reinforcement ratio,steel strand reinforcement rate,steel strand ultimate tensile strength,steel strand elastic modulus,prestress level,The holding level.The ultimate deflection of a member is positively correlated with the longitudinal reinforcement ratio,the reinforcement ratio of the steel strand,the ultimate strength of the steel strand,and the load-holding level;it is negatively correlated with the concrete strength,the elastic modulus of the steel strand,and the prestress level.The parameters that have a significant effect on the ductility of reinforced components are concrete strength,longitudinal reinforcement ratio,steel strand reinforcement ratio,steel strand ultimate tensile strength,steel strand elastic modulus,prestress level,and load-holding level.The component ductility coefficient is positively correlated with concrete strength,steel strand reinforcement ratio,steel strand ultimate strength,and load-holding level;it is negatively correlated with longitudinal reinforcement ratio,steel strand elastic modulus,and prestress level.（4）The existing reinforcement code does not give the calculation formula of the bearing capacity considering the tensile performance of ECC.Based on the finite element simulation and theoretical analysis,this paper derives the high-strength steel wire mesh combined with the tensile strength of the ECC-ECC reinforced RC beam normal section The calculation formula of the ultimate bearing capacity in bending and the calculation formula of the yield strength considering the prestress.The calculated values of the two formulas are in good agreement with the experimental values and the finite element simulation values.