钢-混凝土组合梁中混凝土翼板的收缩应力

忽略钢-混凝土组合梁界面滑移,认为混凝土收缩引起的横截面变形符合平截面假定,由此建立混凝土收缩内力平衡方程和收缩应力计算公式。提出考虑混凝土收缩影响的组合梁混凝土开裂弯矩计算公式,以及混凝土收缩引起的组合梁挠度计算公式。算例表明,在进行组合梁混凝土的抗裂分析时,混凝土的收缩应力不容忽视。混凝土收缩引起的组合梁挠曲变形随组合梁跨高比的增大而迅速增加,大跨度组合梁的收缩挠度可以得到跨度的1/1000以上。对于混凝土翼板恒定的变截面组合梁,混凝土的收缩应力基本不随截面变化。组合梁混凝土收缩应力随混凝土翼板配筋率的提高而增加,但总的变化幅度不大。

Shrinkage Stress of Concrete Flange Slab in Steel-concrete Composite Beam

Based on the assumption that the cross section strain keep flat when concrete shrink,and ignore the slip between the steel and concrete interface,the mathematic model for analysing the steel-concrete composite beam due to the concrete shrinkage is established.Equations of internal force and shrinkage stress are deduced as per strain distribution in cross section.The moment and deflection calculation methods are proposed in consideration of the concrete shrinkage.Numerical test results show that the shrinkage stress of concrete is not negligible on the crack-resistance analysis in composite beams.Also,the deflection due to concrete shrinkage increased rapidly with the increase of the span-height ratio.The portion of deflection due to the concrete shrinkage may exceed 1/1000 of span for long span composite beams.For fixed flange composite beams with variable cross-sections,the concrete shrinkage stress doesn't change with the cross section,it increased with the increase of the flange reinforcement ratio,but the amount is not significant.