中文摘要：

为研究整体结构中钢梁的抗火性能，利用自行研制的试验炉和相关测试装置，对二层三跨足尺钢框架楼中三层顶一两跨连续梁进行受火试验研究，试验中钢梁受火，钢柱和节点不受火。试验量测了炉体内烟气温度、钢梁和混凝土楼板四等分点处截面沿厚度不同点的温度场、位于炉体外钢梁接点温度、钢梁和楼板四等分点处的竖向变形。结果表明：未进行防火保护的钢梁温度与烟气温度基本一致；升温阶段混凝土板温度滞后于钢梁的温度，停止升温后钢梁温度迅速降低，混凝土板温度仍会升高直至两者温度趋于一致。在整个试验过程中，沿混凝土板截面高度存在较大温度梯度；整体结构中未进行防火保护的钢梁具有很好的变形性能，可以考虑减少防火保护；不同位置的构件由于受到相临构件的约束程度不同，在火灾中的变形性能不同，在抗火设计时应进行区别对待；钢柱虽不受火，在整个试验过程中产生轴向膨胀。

英文摘要：

In order to understand the resistance of a steel beam of a structural system in fire, the experimental behavior of a two-span consistent beam of a three-span and three-storey steel frame building subjected to fire is studied with the help of the self-designed furnace and detecting devices. There are only steel beams subjected to fire during the whole test. The temperature of fumace gas, steel beams and concrete floor section temperature at four equal points along the beams, the temperature of steel beam joints located outside the furnaces and the vertical deformations at four equal points along the beams were measured. The results showed that the temperature curves of exposed steel beams were consistent with the furnace gas curve, the temperature rise of concrete was slower than that of steel beams, the temperature of the beams decreased rapidly after the heating, but concrete temperature continued to rise until the two curves were in consistency. In addition, there was a big temperature gradient across the concrete section throughout the experiment. The steel beams without fire protection in the building performed well; therefore, the fire protection of it can be reduced. Fire resistant design of components at different positions should be treated differently, for the performance of different components was varied in the fire due to the constraints of adjacent components. While steel columns generated an axial expansion during the test though they are not exposed to fire.