Calculation of ultimate bearing capacity of Steel reinforced concrete structure under fire

Steel reinforced concrete structure is widely used in various projects because of its high bearing capacity, well aseismatic performance and durability. It is important to study the mechanical properties under fire and reasonable fire resistance design. The mechanical properties curve of materials under fire is simplified to get their calculation model. Calculation formula of steel reinforced concrete beam´s equivalent section area under fire is deduced. Based on the original finite element calculation results, isothermal of 300°C and 800°C determined. Two ultimate bearing capacity formulas of steel reinforced concrete beam are established. One is for the beam whose tensile area is under fire, the other is for the beam whose compression area is under fire. Providing theoretical basis for the engineering design.