体外预应力混凝土梁承载全过程分析新模型

为了探讨体外预应力混凝土梁在承载能力极限状态下的性能,建立了其基于有限单元法的考虑材料和几何非线性的数值分析模型.引入分块截面模型确定钢筋混凝土梁单元截面的切线刚度和分析其退化过程,采用三节点摩擦滑移预应力筋单元分析体外预应力筋在转向块或滑块处的摩擦滑移效应.该模型考虑了影响结构力学性能的主要因素,并考虑了轴力二次矩和二次效应.对试验梁的特征参数、体外预应力增量、摩擦滑移效应和二次效应等进行的分析表明,计算结果和试验值吻合.研究表明,体外预应力筋在转向块或滑块处的摩擦滑移效应是影响体外预应力混凝土梁力学性能的重要因素.

New Model for Full Process Analysis of Bearing Behavior of Externally Prestressed Concrete Beams

Based on FEM(finite element method),a numerical model for an externally prestressed concrete beam was proposed by considering the material and geometrical nonlinearities of this structure in order to investigate its behavior at the ultimate state of bearing capacity.In this model,a grid-section model is introduced to determine the sectional tangent stiffness of reinforced concrete beam element and analyze its degeneration process,and three-node friction-sliding tendon elements are employed to analyze the friction and sliding of external tendons at deviators or sliding blocks.Furthermore,major factors affecting the structural behavior,altogether with the axial second-order moment and the second-order effect,are taken into account in this model.The capability and efficiency of the proposed model were verified by comparing the numerical and experimental results of the characteristic parameters,the external prestress increment,the friction-sliding effect and the second-order effect of experimental beams.The research results show that the friction and sliding of external tendons at deviators or sliding blocks are important factors affecting the structural behavior.