Abstract:

Based on the virtual work principle , a beam-element model of the reinforced concrete and a computer program for analysis of reinforced concrete frames subjected to elevated temperature are proposed , and the geometrical nonlinear behavior is considered. The reliability of the proposed program is then validated according to the test results provided by other researchers. Moreover, a reinforced concrete beam subjected to axial force is selected to make the fire response analysis via the program. The simulated results show that: (a) it is necessary to consider the geometrical nonlinear behavior during the fire response analysis; (b) the mid-span deflection of the beam increases with the increase in vertical loads while the axial force keeps constant , and with an increase in verticalloads , the influence of geometrical nonlinear behavior on the mid-span deflection hardly changes; (c) in the condition of a constant verticalload , the mid-span deflection of the beam gradually increases with the axial force due to the geometrical nonlinear behavior; and (d) the geometrical nonlinear behavior greatly influences the calculated results of fire resistance of the beam.

Key words: reinforced concrete, frame, elevated temperature, mechanical behavior, geometrical nonlinear, numerical simulation