钢-混凝土组合梁的受扭试验与分析

为了研究钢-混凝土组合梁的抗扭性能,完成了4根不同配箍率的组合梁纯扭试验,借助结构分析软件,采用三维8结点实体单元的有限元模型,对组合梁纯扭试件在弹性阶段的变形、截面应力分布情况进行了分析。试验和分析结果表明:受扭承载力主要由混凝土翼板提供,翼板的截面尺寸是影响极限承载力的主要因素,其中翼板厚度对组合梁受扭承载力的影响更为显著;而配箍率对组合梁受扭承载力的影响并不大。其它条件相同时,当配箍率为0.54%左右时,组合梁受扭承载力将达到最大。提出了组合梁弹性抗扭刚度计算公式和开裂扭矩计算公式;本文采用变角空间桁架模型,并结合已有的试验成果,提出了可供设计参考的极限承载力计算公式。公式计算结果与试验值吻合良好。

Torsional experiment and analysis on composite steel-concrete beams

In order to study the torsional behavior of composite steelconcrete beams,experiments were conducted on four specimens with varied stirrup ratios subjected to pure torsion.Then,the torsional deformation and stress distribution of composite beams in elastic range are analyzed using structure analysis software with spatial finite elements of 8 joints.Test and analysis results showed that the torsional carrying capacity of composite steel-concrete beams are undertaken mainly by concrete flange,and the section dimensions of flange are the main effect factors.Moreover,the flange thickness is the most important one.The ultimate torque for composite beams will arrive at maximum under otherwise equal conditions when the stirrup ratio is about 0.54 percent.The formulae about elastic torsion stiffness and cracking torque are presented.Finally,by using spatial truss model with variable angle,a formula for ultimate torsional strength is proposed in which test results are taken into account.The predicted results are in good agreement with the measured ones.