Study On The Fire Performance Of SRC Special-Shaped Column Subjected To Different Fire Exposure Case

The Steel Reinforced Concrete(SRC)columns with special-shaped cross section is a composite columns of steel and rebar embedded in concrete.The structure has beautiful appearance,flexible plane-layout and good ductility and high load bearing capacity.The Steel Reinforced Concrete columns with special-shaped cross section under fire area is large when fire happen,so its fire-resistant ability is poor.The finite element model established under the coupling effects between temperature and load by the finite element software ABAQUS was used to study its fire-resistance performance.The results provide certain important reference value for the fire resistance design of steel reinforced concrete structure.The main research and achievements are as follows:1.The main factors that influence temperature field of column inside the post have cross section shape,cross section area,the time of fire,typical fire exposure case.The rectangular column internal temperature is obviously lower than the SRC special-shaped column internal temperature.There were no obviously differences between the special-shaped columns.The temperature of the steel near the concrete accelerated transmission,that makes concrete-isotherm mutations.2.Explore the destruction mechanism of steel reinforced concrete special-shaped columns in different fire conditions by study the stress variation of concrete,steel and rebar.Under the constant temperature rise load calculating the bearing capacity of the construction,bearing capacity of less than 1/7 of the normal temperature when 2 hours after the fire.3.Analysis fire resistance on related factors such as cross section shape,Section dimensions,load ratio,steel form,steel content,longitudinal bar ratio,load eccentricity ratio,load angle,fire exposure case.Based on a large number of calculation datacollection and analysis,a good formula is given considering the effects of multiple factors.For SRC special-shaped column,when the load ratio is bigger fire-resistance performance of the column with +-shaped section is better than that of the T-shaped section and fire-resistance performance of the column with T-shaped section is better than that of the L-shaped section,but fire-resistance performance of the column with L-shaped section is better than that of the T-shaped section in case that load ratio is smaller.Fire resistance becomes shorter as the load ratio increase,while the increase of the section dimensions will lead to a larger fire resistance.Fire-resistance performance of solid-web steel reinforced concrete special-shaped column is obviously better than the lattice steel reinforced concrete special-shaped column fire-resistance performance.Longitudinal bar ratio has little influence in case that load ratio is smaller.when the load ratio is bigger,fire resistance becomes shorter as longitudinal bar ratio increase.Load angle has little influence in case that fire uniform.when the uneven(FA?FB?FC?FD)fire,the influence is complex.Fire resistance becomes shorter as load eccentricity ratio increase.