高温下约束混凝土子框架的框架梁内力研究

以约束钢筋混凝土子框架作为分析对象,针对不同梁截面尺寸和配筋率、梁跨度、侧向/竖向/转动约束刚度比等情况,利用自编程序开展了高温下约束子框架的框架梁内力研究.研究结果表明：1）高温下框架梁的轴力比和梁端弯矩均呈现出先逐渐增大而后逐渐减小的趋势,前者峰值可达0.35～0.4;2）随着侧向约束刚度比增加,轴力比明显增大,而升温中后期梁端弯矩则逐渐减小;3）梁截面宽度越小,轴力比的增长速率越快且更早达到其峰值;随着梁截面宽度增加,梁端弯矩明显增大.

Study on internal forces in frame beams of retrained RC subframes under high temperature

Restrained RC subframes are analyzed in this paper. The influence of several parameters, such as beam sectional dimensions and steel ratios, beam span and lateral/ vertical/rotational restrained stiffness ratios, on internal forces in frame beams of RC subframes in fire is analyzed. Simulation results show that： 1） the axial force ratio and end moment of a frame beam subjected to high temperature follow a similar tendency as increasing first and then dropping gradually, the peak value of the axial force ratio can reach 0. 35~0.4; 2） with an increasing of lateral restrained stiffness ratio, the axial force ratio increases significantly and the end moment decreases gradually during the mid- and later-stages of heating process; and 3） the less the beam width is, the larger the increasing rate of the axial force ratio is; the end moment increases greatly with increasing of beam width.