部分包覆钢-混凝土钢筋桁架空腹组合梁受剪性能试验研究

Experimental study on shear behavior of partially-encased steel-concrete composite reinforcement truss open-web beams

为研究部分包覆钢-混凝土钢筋桁架空腹组合梁的受剪机理,设计了4根组合梁的缩尺模型,在组合梁腹部设置C形连杆和X形拉结筋,以剪跨比和腹板空腹率为变化参数,进行了受剪性能试验。试验结果表明:当组合梁剪跨比从1增大到3时,组合梁呈现出斜压破坏、约束剪压破坏和斜拉黏结破坏等三种破坏形态;腹板空腹率相同时,剪跨比的增大使梁的受剪承载力显著减小,变形能力提高,相比于剪跨比为1的组合梁,剪跨比为2和3的组合梁受剪承载力分别降低了23.94%和44.08%。C形连杆和X形拉结筋先于腹板达到屈服,腹板在加载后期承载能力得到充分发挥;剪跨比相同时,腹板空腹率的增大使组合梁的受剪承载力减小,腹板空腹率由51.1%增大至67.4%,组合梁的受剪承载力减小了8.82%。在试验基础上,参考JGJ 138—2016《组合结构设计规范》,基于叠加原理提出了钢筋桁架空腹组合梁受剪承载力计算方法,计算结果与试验结果较为接近。

To study the shear behavior of partially-encased steel-concrete composite reinforcement truss open-web beams,the scaled models of four composite beams were designed,the C-shaped connecting rod and the X-shaped bar were set on the abdomen and the shear performance was tested with shear span ratio and web opening ratio as parameters.The results show that the reinforcement truss open-web beams present three failure modes:diagonal compression failure,constrained shear compression failure and cable-stayed bond failure when the shear span ratio increases from 1 to 3.When the web opening ratio is the same,the shear capacity of beams decreases significantly and the deformation capacity increases with the increase of the shear span ratio.Compared with the composite beam with the shear span ratio of 1,the shear capacity of the composite beam with the shear span ratio of 2 and 3 is reduced by 23.94%and 44.08%,respectively.The C-shaped connecting rod and the X-shaped bar reach yielding before the web,and the bearing capacity of the web is fully exerted in the later stage of loading.When the shear span ratio is the same,the shear capacity of the composite beam decreases with the increase of the web opening ratio.When the web opening ratio increases from 51.1%to 67.4%,the shear capacity of the composite beam decreases by 8.82%.Combined with the experiment results and JGJ 138—2016‘Code for design of composite structures’,the calculation method of shear capacity of reinforcement truss open-web beam was proposed based on superposition principle,the calculated results are close to the experimental results.