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对3层钢框架结构边跨梁在火灾作用下的性能进行足尺试验研究,试验中测量了炉温、钢梁和混凝土板沿截面高度的温度场分布以及钢梁和混凝土板的竖向位移。结果表明:钢梁下翼缘、腹板和烟气的温度基本一致;混凝土板内的温度滞后于钢梁温度,且在钢梁降温阶段,混凝土板温度持续升高,因此混凝土板限制了钢梁升温阶段的膨胀和降温阶段的收缩;钢梁在122 min的升温过程中变形较小,且在升温阶段变形就开始恢复,最终出现向上的竖向位移,这是框架结构中钢梁火灾行为区别于单个构件火灾行为的特点之一,表明框架结构中与混凝土楼板形成整体的边跨梁具有较强的抗火性能;最后钢梁上下翼缘焊缝被拉裂破坏,因此在工程应用中应尽量避免工地现场施焊的全焊接节点。利用非线性有限元软件对试验梁进行了火灾反应分析,得出了试验梁的温度场分布和位移反应的变化规律。有限元分析结果和试验结果基本一致,验证了有限元分析模型的正确性和可行性。
Full-scale experimental study was conducted on the performance of side-span girders of 3-story steel frame structures subjected to fire. The temperature field, the temperature distribution along the height of girder and concrete slab, and the vertical displacements of steel girders and concrete slabs . The results show that the temperature of flange, web and flue gas is almost the same. The temperature in concrete slab lags behind the temperature of steel beam. And the temperature of concrete slab continues to increase in the cooling stage of steel beam. Therefore, During the warming process of the beam, the deformation of the beam during the warming process is small, and the deformation begins to recover at the temperature rising stage. Finally, the upwards vertical displacement occurs, which is the behavior of the steel beam in the frame structure Different from the fire behavior of a single component, it shows that the fire-proofing performance of the side span beam which is integral with the concrete floor in the frame structure is strong. Finally, the weld of the upper and lower flanges of the steel beam is ruptured and fractured. Therefore, in engineering application Should try to avoid the site welding all welded joints site. The fire response analysis of the test beam was carried out by using the nonlinear finite element software, and the temperature field distribution and displacement response of the test beam were obtained. Finite element analysis results and test results are basically the same, verify the correctness and feasibility of the finite element analysis model.