Research On Fire Resistance Performance Of Steel Reinforced Recycled Concrete Composite Frame

Similar to the reinforced concrete structures,the steel reinforced recycled concrete structures also have the advantages of high bearing capacity,high rigidity,good ductility,and strong seismic performance.It is energy-saving and environmentally friendly,which meets the requirements of the national green building and sustainable development.At present,most studies at home and abroad mainly focus on the mechanical properties of steel reinforced recycled concrete beams or columns.For this purpose,based on a large number of experimental studies and theoretical analysis by predecessors,the finite element software ABAQUS is used to conduct a numerical simulation study on the fire resistance of the steel reinforced concrete composite frame structure.The design parameters that influence the fire resistance of the steel reinforced concrete composite frame include axial compression ratio,steel content and load level,etc.In addition,the influence of fire resistance performance,and the residual bearing capacity of the structure after the fire is analyzed.The main research contents are as follows:(1)Based on the research results of the thermal properties and the mechanical properties of steel and recycled concrete under the high temperature at home and abroad,the thermal parameters of steel and recycled concrete were selected to study the distribution of the temperature field of the steel reinforced recycled concrete composite frame under different fire conditions.The results show that the temperature hysteretic effect was obvious inside the composite structural under high temperature,and the distribution of the temperature field of the sectional surface under different fire conditions is quite different.(2)The finite element analysis software was used to simulate and verify the fire resistance test of the combined frame structure.The analysis and calculation results are in good agreement with the test results,so it is proved that the model parameters used are more reliable.After that,fourteen sets of one-layer and three-span steel regenerated concrete composite frame numerical models were established.The laws of displacement deformation of this model under different fire conditions and load conditions were explored and analyzed.The results show that the greater the axial compression ratio of the column,the longer the fire time of the structure,the more severe the degradation of the fire resistance performance of the corresponding member at high temperature;The higher the steel content of the composite beam,the smaller the mid-span displacement of the beam;Appropriate load levels help to improve the fire resistance of the combined structure.(3)Based on the analysis of fire resistance of the steel reinforced recycled concrete composite frame,a post-disaster model of the steel reinforced recycled concrete frame considering the whole fire process was established,and the effects of fire time,load level and other parameters on the mechanical properties of the composite frame were analyzed.The results show that the greater the axial compression ratio of the column,the longer the fire time of the structure,the more severe the degradation of the fire resistance performance of the corresponding member at high temperature;The higher the steel content of the composite beam,the smaller the mid-span displacement of the beam;Appropriate load levels help to improve the fire resistance of the combined structure.