| Because of its inherent shortcomings,concrete can not meet the performance requirements of people.Adding steel fiber can effectively improve the original shortcomings of concrete and optimize its performance.Therefore,steel fiber concrete is widely used in airport runway,bridge deck pavement,reservoir dam and beam column frame joints.In the above working conditions,structural members are often subjected to reciprocating load,and the fatigue failure of members is easy to occur,which shortens the service life of members.In recent years,many scholars have studied the static and fatigue of steel fiber reinforced concrete,but most of them are experimental research,and the research on the meso level is relatively less.In this paper,the static and fatigue failure of steel fiber reinforced concrete is analyzed,the main research contents are as follows:(1)The elastic modulus of SFRC is predicted by M-T homogenization theory and finite element method,and the influences of steel fiber content,aggregate shape and fiber length-diameter ratio on the elastic modulus are discussed.By comparing with the experimental results,the error between the calculated results and the experimental results is less than 5%.The elastic modulus of concrete increases with the increase of steel fiber content,but the variation amplitude of the elastic modulus is less than 1%after the change of aggregate shape and fiber length-diameter ratio.(2)The 3D model was transformed into 2D model by using Walraven formula,and the random aggregate model was generated by Monte Carlo method.After the zero thickness bonding element was embedded,the axial compression analysis of SFRC was carried out.The calculated curve is in good agreement with the test curve,and the error of peak stress is less than 2%.The influence of steel fiber content and aggregate shape(round,oval,polygon)on the compressive performance of steel fiber reinforced concrete is analyzed.The results show that the axial compressive strength of steel fiber increases by 57.72% with the addition of 2%,and the amplitude of axial compressive strength changes is less than 3% when the aggregate shape changes with the same content.(3)Based on the static results of steel fiber reinforced concrete(SFRC),the fatigue performance of SFRC is analyzed.Compared with the experimental results,the error between the two is less than 5%.The effects of steel fiber content and aggregate shape(round,oval,polygon)on compression fatigue performance of SFRC are analyzed.The results show that when the stress level is 0.9,the fatigue life of steel fiber increases by 5times and the fatigue strength increases by 86.448% when the content of steel fiber increases to 2%.However,the fatigue life increases by about 20% and the fatigue strength increases by about 7% when the aggregate shape changes under the same content,and the fatigue life and the fatigue strength increase are relatively small.(4)The static and fatigue failure properties of steel fiber reinforced concrete beams are analyzed by tri-point loading,and the calculated results are compared with the test results,which show a good fit between them.The influences of steel fiber content and aggregate shape(round,oval,polygon)on the static bending strength and fatigue bending performance of the beam are analyzed.The results show that when the steel fiber is increased to 2%,the bending strength of the beam is increased by 82.85% and the fatigue strength is doubled,while the change of aggregate shape has little effect on the bending strength and fatigue bending performance.In addition,Paris formula is used to analyze the crack propagation of steel fiber reinforced concrete beam under fatigue load,and the results are similar to the test curve.The effects of different steel fiber content on fatigue crack propagation of concrete beams are analyzed.The results show that the crack growth presents three stages,and the loading times of the stable crack growth stage increase obviously with the increase of steel fiber content. |
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