Study On Compressive And Flexural Behavior Of CFST Reinforced Concrete Columns After Exposure To Standard Fire

The concrete filled steel tube reinforced concrete(CFSTRC)column has the advantages of high bearing capacity,good ductility and good durability.But there is very little research work on postfire behavior of this kind of structure under compressive and flexural loads.In order to analyze the influence degree under fire and compressive and flexural failure mechanism after fire of the CFSTRC columns the paper will conduct the test and theory research of CFSTRC column.The main research work and achievements inckudes:(1)The paper describes the test studies in fire according to ISO-834 heating up curve and the compressive and flexural behavior after natural cooling by sixteen changing parameters CFSTRC columns and records the development process of cracking and the change trend of load,displacement and strain.Sorting out and analyzing data obtained development regularity of temperature of various typical points in furnace and the component in fire?the axial load-displacement and axial load in cross-across the strain curve after the fire as well as typical failure mode under fire and after fire.Results show that fire duration time,concrete filled steel tube ratio and eccentricity have much effect on the ultimate compressive bearing capacity of components,and changing length has relatively little impact on its strength.(2)Combined with project research results,based on ISO-834 standard heating up curve and the test properties of materials at room temperature andpost-high-temperature,temperature field and static simulation of CFSTRC were developed by finite element analysis(FEA)software ABAQUS.Axial load-displacement curve,ultimate bearing capacity by test and typical failure mode of test and FEA were analyzed and the results were reasonable and effective.By comparing test results with simulation verification,the results of FEA analyzes the whole process of stress getting its compressive and flexural mechanics performance extremely working mechanism from the development of specific detailed analysis of the CFSTRC.(3)Overall analysizing some factors that may affect fire bending residual bearing capacity and residual bearing capacity coefficient r,which include the time in fire,concrete filled steel tube ratio,steel ratio,types of steel,concrete strength,eccentricity and length of component,fire-resistant capacity-time curve and residual bearing capacity coefficient-time curve were established.Introduced normal temperature formula of effect coefficient of bending bearing capacity and based on parameter analysis of CFSTRC,the paper returns the simplified effect coefficient formula related parameters of CFSTRC Columns under Compressive and Flexural Behavior after Exposure to standard Fire and the results were reasonable.