Research On Mechanical Behavior Of Prefabricated Steel Reinforced Concrete Beams After High Temperature

The prefabricated SRC structure not only has the advantages of good seismic performance,high bearing capacity,and excellent fire resistance,but also has the features of high degree of industrialization,short construction period,low energy consumption,low emission,and other fabricated structures,at the high level and super high level.The building has a wide range of application prospects.Due to the high probability of high-rise building fires,and the structure of buildings may be destroyed in the fire cooling section,this paper analyzes the performance of PSRC beams subjected to high temperature based on the analysis of the whole process of temperature rise and fall.The main work is as follows:Based on this,this paper studied the mechanical properties of PSRC beams after high temperature.The main research work is as follows:1.Define the field variables and compile the subroutine USDFLD to automatically identify and convert the constitution of the material during the ramp-up and down phase,and realize the call to the material properties of the cooling section of the PSRC beam.2.After determining the constitutive relations of steel and concrete at different stages of temperature increase,temperature drop and high temperature,the finite element software ABAQUS was used to establish the temperature field and high temperature prefabricated assembly of the prefabricated assembly and the entire cast SRC beam under the effect of fire temperature rise and fall.The analysis model of the mechanical properties of the whole cast SRC beam,and the use of the existing experimental data to verify the rationality of the model.3.The working mechanism of the PSRC beam after high temperature was calculated and analyzed,including: temperature-time relationship,load-displacement relationship,failure mode,longitudinal stress distribution of concrete in mid-span section,plastic tensile strain of concrete,temperature of overlap surface and slippage with time.4.Comparing and analyzing the mechanical performance of prefabricated SRC beam and cast-in-place SRC beam after the whole process of temperature rise and fall.Through comparative analysis,it can be seen that during the heating and cooling stage,with the increase of the heating time,the maximum temperature in the section increases,and the bond strength of the laminated surface decreases.Prefabricated SRC beams are more likely to be damaged than the entire SRC beam;In the loading stage,the residual stress performance of the cast-in-place SRC beam is slightly better than that of the prefabricated SRC beam.Based on the numerical simulation,the prefabricated SRC beam can basically meet the requirements of the whole-concrete SRC beam in practical engineering.5.The parameters that affect the stress performance and bearing capacity reduction of high-temperature PSRC beams subjected to high-temperature analysis based on the whole process analysis are calculated and analyzed,including: concrete strength,yield strength of steel beams,yield strength of longitudinal beams of web beams,height of profiled steel bars,height-to-height ratio,and shear span Ratio,load ratio,heating time.According to the comparative analysis,the heating time,load ratio,and shear-span ratio have significant influence on the mechanical properties of PSRC girder after high temperature.The heating time has a significant effect on the reduction of bearing capacity,which is a decrease of 21% to 30%.