收缩对混凝土组合板长期应力与变形的影响

混凝土板和钢面板组合而成的单向板常作为永久模板在建筑结构中得到广泛应用。钢面板在浇筑混凝土时作为模板,待混凝土凝固后作为外部加固构件。这类板的使用性能具有时间依赖性,目前对其研究较少,在计算长期变形时为结构工程师提供的指导也较少。众所周知,板底部的不透水钢面板对沿组合板板厚分布的混凝土干燥收缩特性有着重要影响,但该影响尚未被量化。通过试验测定了沿组合板板厚非均匀分布的收缩特性,考虑了该结果对这类板长期变形的影响。组合板的应力与变形随时间变化而变化,该文描述了确定组合板应力和变形的分析过程,通过所测量的收缩特性,给出几种常见板型的分析结果。

Effects of Shrinkage on the Long-Term Stresses and Deformations of Composite Concrete Slabs

Composite one-way concrete floor slabs with profiled steel decking used as permanent formwork are commonly used in the construction of floors in buildings. The steel decking supports the wet concrete of a cast in situ slab and, after the concrete sets, acts as external reinforcement. Relatively little research has been undertaken on the time-dependent in-service behaviour of such slabs and little guidance is available to structural engineers for predicting the long-term deflection. The drying shrinkage profile through the thickness of a slab is known to be greatly affected by the impermeable steel deck at the slab soffit, but this has not been quantified to date. This paper presents the results of laboratory measurements of the non-uniform distribution of shrinkage through the thickness of composite slabs, and the resulting effects on the long-term deflection of such slabs are considered. An analytical procedure for the determination of time-dependent stresses and deformations in composite floor slabs is described, and the results of analyses are presented for several common decking profiles using the measured shrinkage profiles.