Nonlinear Finite Element Analysis of Transient Thermal Field for RC Special -Shaped Columns in Fire

摘要

A nonlinear finite element program RCSSCF is proposed for determining the two-dimensional (2D) or three-dimensional (3D) transient thermal fields in reinforced concrete (RC) special-shaped columns exposed to fire. The validation of the program is examined by experimental results. The transient temperature field in RC special-shaped columns with various cross section shapes (e. g. , + -shaped, T-shaped and L-shaped) and subjected to fire with ISO834 standard heating process is, respectively, determined using the proposed program. Simulation results indicate that temperature in RC special-shaped columns rise more quickly than those in rectangle columns, and the region where temperatures exceed 500℃ in cross section of RC special-shaped columns is larger than those of rectangle columns. Therefore, the fire resistance of special-shaped columns is lower than that of rectangle columns. Finally, the temperature field in RC columns of which only the middle parts along the height is exposed to fire (e. g. , columns tested in a fire furnace) is analyzed using the proposed program. It is shown that along the longitudinal direction of RC columns, little change in the thermal field occurs except for the zones near to the top and the bottom of the furnace.