任意截面无粘结预应力混凝土梁的极限非线性分析

在材料非线性应力-应变关系基础上,提出了确定任意截面无粘结预应力混凝土梁抗弯强度以及计算无粘结预应力筋极限应力的通用方法。利用修正的RODRIGUEZ截面模型进行截面强度分析,按截面顶点把截面划分为若干个梯形单元,通过对梯形单元积分求出混凝土内力。将极限状态下无粘结预应力梁等效塑性区长度与破坏截面中性轴高度之比看作一常数,通过对引自7个不同文献的140片无粘结预应力试验梁的非线性回归分析,认为这个常数取为9.78较为合理。计算结果与试验值吻合较好。

Nonlinear analysis of unbonded prestressed beams with arbitrary section at ultimate

Based on nonlinear stress-strain relationships of materials, a general method for determining the flexural strength of unbonded prestressed concrete beams with arbitrary section and for calculating the ultimate stress of unbonded tendons is presented. Sectional model suggested by RODRIGUEZ is revised and utilized to perform sectional strength analysis. Section is partitioned into several trapezoids according to sectional vertices. Internal force of section contributed by concrete is obtained through integrating trapezoids one by one. The ratio of equivalent plastic region length developed in unbonded prestressed beam at ultimate state to neutral axis depth of failure section is considered as a constant. The constant value of 9. 78 is considered to be rational through nonlinear regression analysis of 140 unbonded prestressed test beams from seven different literatures. Computational results agree well with test data.