NUMERICAL SIMULATING ANALYSIS FOR RESIDUAL LOAD BEARING CAPACITY OF STEEL REINFORCED CONCRETE COLUMNS AFTER EXPOSURE TO FIRE

The numerical simulating analysis for the sectional temperature field and residual load bearing capacity of steel reinforced concrete columns after exposure to fire is carried out by using element analysis software MSC.MARC. The simulating results are verified to be correct by test results. Then, the influence of parameters, such as concrete strength, slenderness, steel ratio, load eccentricity and temperature elevating time on residual load bearing capacity of steel reinforced concrete columns after exposure to ISO834 standard fire is studied by using MSC.MARC. Numerical simulating results show that the ultimate strength of steel reinforced concrete columns after exposure to ISO834 standard fire decrease remarkably, compared with that at normal room temperature. The decreasing degree is ranged from 8.5% to 45.3% in the parameters designed. The ratio of residual strength after exposure to fire to ultimate strength at normal room temperature of steel reinforced concrete columns is defined as residual-load-bearing-capacity influence coefficient . Results from numerical simulation show that concrete strength, steel ratio, and temperature elevating time have remarkable influence on, while slenderness and load eccentricity have little effect on . The simplified calculating formula for is put forward by a regression method in the base of numerical simulation results, and the calculating results from formula show that there is a well agreement between the analyzing results and numerical simulation results.