空间约束钢-混凝土组合楼盖抗火性能试验研究

整体结构中钢-混凝土组合楼盖的抗火性能和与其直接相连的周边部件提供的约束力关系密切,但以往研究中却难以获得约束力的真实大小.为此,设计了空间约束钢框架,用以模拟真实结构中钢-混凝土组合楼盖的边界条件,同时可测得约束力的大小.通过开展带空间约束框架的钢-混凝土组合楼盖的受火试验,获得了组合楼盖的裂缝发展过程、破坏特征、温...

Experimental study on behavior of steel-concrete composite floor with spacial restraints subjected to fire

Fire resistance of steel-concrete composite floor in an overall structure has a direct relationship to its restraint forces provided by the surrounding structural elements,but it is very difficult to measure the corresponding restraint forces.In order to simulate the real edge restraint condition and to obtain the value of restraint forces,a new device,mainly composed of a spatial steel-frame structure,was designed and fabricated with the steel-concrete composite floor in this paper.A fire test was conducted on the steel-concrete composite floor with spatial restraints to observe the development of cracks and to explore the final failure modes.In addition,the temperature field,vertical and horizontal displacements,rotational angle and restraint forces at the corner of the slab,were all collected during the test.It is shown that the fire-resistance time of the steel-concrete composite floor is 300 min,at which moment the temperature on the slab surface reaches 180℃,so indicating that thermal insulation is compromised.The testing data indicated that the maximum vertical displacement,105.8 mm,is approximately 1/34 of the length of the shorter span.A strong displacement-recover phenomenon occurrs at the cooling stage,with a ratio of as high as 47.8%,and this phenomenon is due to the strength recovery of the steel secondary beam under the slab.The effect of restraint forces at the corner of steel-concrete composite floor is obvious,and the restraining action includes the restraint moments and warping forces.The warping forces are significant and have an inverse variation range at the elevated and cooling stage,and it could be a potential hazard to the columns at the adjacent storey.