考虑非均匀收缩影响的钢-混凝土组合板长期挠度设计方法研究

Design method for long-term deflections of composite steel-concrete slabs considering non-uniform shrinkage effects

为研究沿截面高度混凝土非均匀收缩对钢-混凝土组合板长期挠度的影响,基于国内外现有组合板长期性能的试验研究确定了组合板非均匀收缩预测模型;采用MATLAB语言,建立了可考虑非均匀收缩、徐变及混凝土开裂综合影响的组合板非线性有限元模型,据此系统分析了各参数对组合板收缩挠度的影响;沿用现有组合板设计规范中有效刚度的概念,提出了可考虑非均匀收缩影响的组合板长期挠度计算公式。研究结果表明,由非均匀收缩引起的挠度占组合板长期挠度的58%~86%,组合板设计时不应忽略非均匀收缩的影响;混凝土抗压强度和组合板跨高比对组合板收缩挠度的影响较大;所提出的组合板长期挠度计算公式预测结果与有限元分析结果吻合较好,公式预测结果与有限元分析结果比值的均值为0.971~0.997,判定系数R2为0.803~0.815。

Existing long-term tests of composite steel-concrete slabs were summarised to investigate the influence of non-uniform shrinkage distributions on their long-term deflections,based on which the model to predict the nonuniform shrinkage profiles through the thickness of composite slabs was determined. A finite element model( FEM)was established based on MATLAB software,accounting for combined effects of non-uniform shrinkage,creep and concrete cracking,and a parametric study was then carried out to evaluate the effects of various parameters on the shrinkage deflections of composite slabs. Following the way to calculate the effective stiffness of composite slabs,design procedures to calculate the deflections induced by non-uniform shrinkage profiles were proposed for composite slabs. The results indicate that the deflections due to the shrinkage distributions account for 58%-86% of the total deflections of composite slabs. Concrete compressive strength and span-to-depth ratio are the key parameters that influence the shrinkage deflections of composite slabs. The results obtained by proposed design procedures are in good agreement with FE results,with the ratio of 0. 971-0. 997 and the correlation coefficient R^2 of 0. 803-0. 815.