新旧混凝土组合梁收缩徐变影响下的内力计算的组合梁单元法

The Method of Composite Beam Element for Internal Force Computation of New-Old Concrete Composite Beams with Shrinkage and Creep

新旧混凝土组合梁中混凝土自身的收缩徐变会产生应力重分布,为了有效地计算截面内力,提高计算精度,首先推导了考虑混凝土收缩徐变影响的新旧混凝土组合梁结构的以挠度表达的平衡微分方程,以该方程的齐次解作为组合梁的位移函数,给出了组合梁单元刚度矩阵和等效节点荷载,建立了考虑界面滑移的的组合粱单元法,为较好地分析由组合梁组成的复杂结构提供了有力的工具。该法计算简便,仅需在现有有限元程序的基础上,增添文中推导的组合梁单元刚度矩阵和等效节点荷载,同时,计算精度高,且精度不会因单元划分的多少而改变,从理论上讲是一个精确解法。

Shrinkage and creep of concrete may cause stress redistribution in new-old concrete composite beams. In order to effectively calculate internal forces of the cross-section and improve the calculation accuracy for composite beams considered the effect of shrinkage and creep, balance differential equation for composite beams expressed in deflection was derived. Taking the homogeneous solution to this differential equation as the displacement function of new-old concrete composite beams, the element stiffness matrix and equivalent node loads were given. Composite beams element method for interface slip of new-old concrete composite beams, an effective and powerful tool ,was offered for better analyzing the complicated structure made up of the composite beams. This method can be very conveniently used, only by adding the composite beam element and equivalent node load that were derived in the paper to the exist FEM program,while it has very high precision and the calculation precision will not change at all with different division nodes,which makes it theoretically a precise solution.