| Reactive powder concrete has higher compressive strength,flexural strength and elastic modulus.The steel reinforced reactive powder concrete structure formed by placing the section steel in the reactive powder concrete not only perfectly inherits all the advantages of the steel reinforced concrete structure,but also improves the mechanical properties of the structure and prolongs the structure service life.With the development of super high-rise buildings and longspan structures,this structural form has been widely used.However,in natural disasters such as earthquakes,the bond performance between the section steel and reactive powder concrete is the basis of their cooperative work,and it is necessary to carry out experimental research on the bond performance of the interface.In this thesis,taking the thickness of concrete cover,anchorage length of section steel,spacing of stirrups,steel content and isolation part of section steel as the main parameters,23 steel reinforced reactive powder concrete specimens are designed for uniaxial push-out bond performance test.According to the test results,the following main conclusions are obtained:（1）The push out test whole process of 23 specimens is observed and analyzed in detail,and the laws of crack distribution and failure mode are summarized.The cracks at the loading end are mainly 45° inclined cracks and horizontal cracks;The side cracks are mainly vertical cracks and inclined cracks,and the cracks are mainly developed from the cracks at the loading end;The generation of cracks is mainly related to the stress of section steel flange.（2）The load displacement curve of steel reinforced reactive powder concrete specimen is established,and the average bond strength displacement curve is established.The interfacial bond law between section steel and reactive powder concrete is described by using the average bond strength.（3）With the increase of concrete cover thickness,the bond stress increases significantly;With the increase of anchorage length of section steel,the bond stress decreases;With the decrease of stirrup spacing,the bond stress hardly changes;With the increase of steel content,the bond stress decreases;The bond stress of section steel web and flange is approximately equal.The regression calculation formulas of bond stress and slip value under the independent action of various influencing factors are established.（4）The thickness of concrete cover has a great influence on the proportion of friction,while the anchorage length of section steel,stirrup spacing and steel content have little influence on the proportion of friction.The relationship between the proportion of friction and various factors is put forward;Increasing the thickness of concrete cover and steel content and reducing the stirrup spacing are more conducive to the dissipation of bond energy at the interface between section steel and reactive powder concrete,while increasing the anchorage length of section steel has a weak effect.（5）The grey correlation theory is used to calculate the correlation between the ultimate bond stress,ultimate state slip value,residual bond stress and residual state slip value and various factors;The correlation degree of each factor is between 0.6 and 0.8,which has good correlation.The thickness of concrete cover,the anchorage length of section steel,the spacing of stirrups and the steel content are the main factors affecting the bond stress and slip value.（6）Based on the correlation degree of each factor,the optimal calculation models of ultimate bond stress,ultimate state slip value,residual bond stress and residual state slip value are established.The test values are in good agreement with the calculated values,and the optimal calculation model meets the calculation requirements.The spatial distribution of ultimate bond stress,ultimate state slip value,residual bond stress and residual state slip value under the action of the two factors are analyzed and drawn.（7）The correction method of different interface bond strength of section steel is put forward,the problem of inaccurate interface bond stress data caused by isolation effect is eliminated,and the internal mechanism of different interface bond strength in section steel is analyzed;The calculation formula of natural bond anchorage length of section steel is put forward,and the anchorage length of section steel for reactive powder concrete to ensure safety is defined under the action of natural bond;The calculation formula of critical concrete cover thickness is put forward,and the concrete cover thickness required to ensure that there are no obvious cracks on the concrete surface is defined;The calculation formula of minimum stirrup ratio is proposed,and the stirrup spacing required to avoid the yield failure of stirrups is defined;The bond slip constitutive models under different concrete cover thickness,section steel anchorage length,stirrup spacing,steel content and section steel isolation are established,which has important guiding significance for the mechanical properties analysis of steel reinforced reactive powder concrete structure. |
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