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通过4根钢筋混凝土T形截面连续梁在ISO 834标准升温曲线下耐火极限的试验研究,分析不同持荷水平下三面受火T形截面连续梁的耐火极限变化规律。结果表明:未受火对比试件和受火试件均发生弯曲破坏,但出铰次序不同;持荷比分别为0.3、0.5和0.7的T形截面连续梁的耐火极限分别为160、99、58 min,即随着持荷比的增大其耐火极限显著降低,且达到耐火极限时的跨中残余变形明显增大;T形截面梁翼缘内温度分布与单面受火板相似,腹板内温度分布与三面受火矩形梁相似;在受火过程中,梁截面刚度下降是引起内力重分布的主要原因;有限元模拟能准确预测钢筋混凝土T形截面连续梁在ISO 834标准升温曲线下的耐火极限、截面温度场分布和破坏过程。
Through the experimental research on the fire resistance of four reinforced concrete T-section continuous beams under the ISO 834 standard temperature rise curve, the variation of fire resistance of three continuous T-beams exposed to different load levels is analyzed. The results show that the flexural damage of uncooled specimens and the exposed specimens is different, but the order of the unfolded joints is different. The fire resistance of T-shaped continuous beams with load-holding ratios of 0.3, 0.5 and 0.7 are 160 and 99, respectively, 58 min, that is, as the load-carrying ratio increases, the fire-resistant limit decreases significantly and the residual deformation in the mid-span of the T-shaped beam increases obviously. The temperature distribution in the T- The temperature distribution is similar to that of the rectangular fire beam with three sides. During the fire, the decrease of the beam section stiffness is the main reason of the internal force redistribution. The finite element simulation can accurately predict the strength of the T-section continuous beam of reinforced concrete under the ISO 834 standard curve Fire resistance, cross-section temperature field distribution and failure process.