| Reactive powder concrete is a new type of high-performance cement-based material with the characteristics of high strength,good durability and high ductility.Designing the reinforcement of reactive powder concrete specimens,it is necessary to configure higherstrength steel bars for matching,so as to fully use to the performance of reactive powder concrete materials.HRB500 steel bars not only have high strength,but also have good ductility.Combine it with reactive powder concrete to form a high-strength reinforced reactive powder concrete beam.At present,the research on the performance of HRB500 high-strength reinforced reactive powder concrete beams mainly adopts test methods,but the test method cycle is long and the test cost is high.With the development of finite element method theory,the use of finite element method to study the performance of specimens has been popularized.The finite element method can provide more test data and shorten the test cycle.At the same time,the results of the finite element model conform to the test law in most cases.Therefore,an effective finite element model of reactive powder concrete beams is established,and the influence of different factors on the shear performance of high-strength reinforced reactive powder concrete beams is analyzed,which provides a method for studying the shear performance of reactive powder concrete beams.In this thesis,by selecting appropriate compressive stress-strain and tension stress-strain constitutive relations of reactive powder concrete to simulate the deformation of reactive powder concrete materials,the constitutive relations of steel bars are selected according to the yield and deformation of the steel bars in the test,and the constitutive relations of the steel bars are established based on the experimental subjects.A lot of trial calculations have been done on the values of model parameters,loading methods,and convergence criteria to obtain good simulation results.The results of the finite element model are compared with the test results.The results show that the load-deflection curve,crack distribution and failure state calculated by the finite element method are consistent with the test results.On this basis,10 finite element models were established for simulation tests according to the factors that affect the shear bearing capacity including: shear span ratio,stirrup ratio,longitudinal reinforcement ratio and steel strength.The analysis of the finite element results of the specimen includes:(1)The stress cloud diagram of reactive powder concrete beams at different stages obtains the change of beam stress with the increase of load.(2)The tensile damage cloud map of reactive powder concrete beams obtains the cracking and evolution of beam cracks.(3)Deformation stress cloud diagram of the steel frame to obtain the deformation of the steel frame at different stages of the beam.(4)The load-deflection curve of the specimen obtains the changes in the shear bearing capacity of the reactive powder concrete beams at different stages.By analyzing the test data,the influence of different factors on the cracking load and ultimate load of the specimen is obtained,and the reasons for the shear failure of the reactive powder concrete beam are further revealed.The results show that the shear span ratio has a certain effect on the ultimate load of the specimen,but has little effect on the cracking load of the beam.As the beam shear span ratio increases,the shear capacity of the beam decreases;As the ratio of stirrups,the ratio of longitudinal reinforcement,and the strength of steel bars increase,the shear capacity of beams also gradually increases.Based on the analysis of the factors affecting the shear performance,combined with the current domestic and foreign codes,the shear bearing capacity of the specimen is calculated,and compared with the finite element calculation results,a suitable formula for calculating the shear bearing capacity of high-strength reinforced reactive powder concrete beams is selected. |
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