考虑梁变形影响的混凝土双向板的挠度分析

Nonlinear Analysis of Deflection of Concrete Two-way Slab Considering Beam’s Deformation

目前在工程中通常按线弹性薄板小挠度理论计算双向板的变形值,且不考虑支承梁变形影响,所得计算结果与实际情况偏差较大,当板跨度较大、梁刚度较小时尤其明显。为此,在分析钢筋混凝土双向板的挠度时,考虑材料非线性和几何非线性非常必要。本文采用增量迭代法编制了非线性有限元程序,对承受均布荷载且考虑支承梁变形影响的单块钢筋混凝土双向板在正常使用阶段的非线性特性进行了探讨。通过调整实际支承梁刚度与板刚度的比值,即梁板相对刚度比值,对钢筋混凝土双向板进行了计算,最后通过非线性回归建立了框架结构中双向板在实际支座条件下的挠度计算公式。

Reinforced concrete two-way slabs are widely used in industry and civilian constructions, especially along with the development of long-span, large space buildings. The longer the span of the reinforced concrete two-way slab, the more important of the forecast the deflection of the slab in normal stage. At the present, the elastic thin-slab flexure theory is usually adopted when the deflection of slab is calculated, what＇s more, the support beams are always considered as the rigid mount. These results in the huge difference between calculation results and practical circumstances, especially when the span of the slab is long and the rigidity of beam is small, the difference is huger. Therefore, the nonlinear analysis of reinforced concrete two-way thin-slab is necessary and the deforming of the beam must be considered. The nonlinear finite element program of R.C two-way thin-slab in frames is designed with combination of incremental and iterative method. The R.C two-way slab carries uniformly distributed load and is supported in the four sides with beams in the design working stage. By modulating the ratio of rigidity of beams and slab, the deflection of slab is obtained. With the help of nonlinear regression, the deflection expression of R.C four sides supported by beams two-way slab is presented.