基于桁架模型的RC膜单元在剪力作用下反应的计算方法

COMPUTATIONAL METHOD FOR THE RESPONSE OF RC MEMBRANE ELEMENT UNDER SHEAR UPON THE TRUSS MODEL

  • 摘要: 软化桁架模型采用修改后的材料本构关系计算钢筋混凝土构件在剪力作用下的反应,本质上是一种等效单元法。这种方法不能直观反映内部真实应力且计算过程较复杂。该研究基于考虑粘结应力影响的桁架模型,采用未经修改的钢筋和混凝土的本构关系,提出了一种直接计算钢筋混凝土(RC)膜单元在剪力作用下反应的方法。基于考虑粘结应力的桁架模型计算出混凝土和钢筋中的最大应力;基于混凝土的本构关系计算出单元的主压应变;建立起钢筋的最大拉应力和单元的主拉应变之间的联系。和实验数据的对比显示,该方法可以较好的预测RC膜单元在剪力作用下的应变,并直接通过钢筋和混凝土的最大应力判断单元的破坏。此外,不同破坏形式的变形特点也可以从预测的应力-应变曲线上清晰反映出来。该方法物理意义明确、计算过程简单,可以应用于RC膜单元在剪力作用下反应的计算,使单元的破坏过程更容易理解。

     

    Abstract: The softened truss model is essentially an equivalent element method, in which the response of reinforced concrete (RC) members under shear is calculated with the modified constitutive laws of materials. This method cannot directly calculate the real internal stress and the calculation is complicated. Based on the truss model considering the effect of bond stress, another method was proposed to directly calculate the response of RC membrane elements under shear without using modified constitutive relations of steel and concrete. The maximum stress in the concrete and steel bars was first calculated upon the truss model considering the bond stress. The principal compressive strain of the element was calculated upon the constitutive relationship of plain concrete. The relationship between the maximum tensile stress in the steel and the principal tensile strain of the member was established. The comparison between the analytical and the experimental results shows that the method proposed can well predict the strain of RC membrane elements under shear, and directly judges the failure of the element through the maximum stress in the steel bar and concrete. In addition, the deformation characteristics of different failure modes can be clearly reflected from the predicted stress-strain curves. This method has clear physical meaning and simple calculation process. It can be applied to the calculation of the response of RC membrane elements under shear, making the failure process of the element easily understood.

     

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