Analysis Of The Failure Mode And Bearing Capacity Of The Oblique Section Of Reinforced Concrete Beams Under Thermal And Mechanical Coupling

The reinforced concrete structure occupies the main share in the current construction project.Under the thermo-mechanical coupling effect,the mechanical properties of the rebar and the concrete material are severely degraded,resulting in a reduction in the bearing capacity of the structure and endangering the safety of the structure.Therefore,the fire resistance of reinforced concrete structures has become a hotspot in the field of structural engineering and disaster reduction and prevention research at home and abroad.At present,there have been many research results on the flexural bearing capacity of normal section of reinforced concrete beams under the thermo-mechanical coupling effect,while there are few research results on the shear bearing capacity of oblique section of reinforced concrete beams under the thermo-mechanical coupling.Therefore,this article takes the simple supported reinforced concrete beam under the concentrated load as the research object to study the bearing capacity of the oblique section of reinforced concrete beam under the thermo-mechanical coupling effect.By analyzing the shear mechanism of the oblique section of the simply supported reinforced concrete beam under the thermo-mechanical coupling,a corresponding calculation model is proposed to establish the calculation formula of the bearing capacity of the oblique section of reinforced concrete beam under the thermo-mechanical coupling.The main research contents of this article are as follows:1.A brief summary of the main domestic and foreign research results on the mechanical properties of steel and concrete materials under high temperature.The process and results of the experimental research on the shear resistance of reinforced concrete beams subjected to fire are briefly introduced,and the bearing mechanism and failure mode of the test beams are analyzed.The analysis laid the foundation for theoretical and experimental research.2.Based on the completed research results of the shear resistance performance of the reinforced concrete beam under fire,combined with the heating characteristics of the three-sided fire beam cross section,the distribution law of the cross-section temperature field of the beam under three fires was analyzed,and a simple and suitable temperature was established.Field calculation model.Based on the experimental research results and referring to the shear resistance mechanism of the reinforced concrete beam at normal temperature,thebearing mechanism and failure mode of the reinforced concrete beam under the thermal coupling are analyzed,and the shear resistance of the reinforced concrete beam under the thermal coupling The calculation model of bearing capacity establishes the calculation method of the shear bearing capacity of reinforced concrete beams under the thermal coupling,and compares the calculation results with the test results.The agreement is good.3.Based on the analysis of calculation examples,the deterioration trend of flexural bearing capacity and shear bearing capacity of reinforced concrete beam under thermal-mechanical coupling is calculated and analyzed.The change rule of the proportional relationship between the bearing capacity and the shear bearing capacity of the beam.