后张预应力混凝土梁钢束锚固损失研究

Research on anchorage loss of tendon in post-tensioned prestressed concrete beams

从分析后张曲线预应力钢束微段的切向平衡条件出发,导出计算锚固损失的精确公式。通过比较在反摩阻影响长度范围内钢束应力相对于端部应力的增量与摩阻损失之间的大小,揭示摩阻作用与反摩阻作用之间的差别。结合数值算例,评价我国现行桥梁设计规范中锚固损失计算方法的近似程度。研究结果表明:反摩阻作用小于摩阻作用;我国现行铁路桥梁设计规范中的锚固损失计算方法具有较高的精度,求得的钢束端部锚固损失计算值大于精确值,但不超过10%;我国现行公路桥梁设计规范中的锚固损失计算方法会导致偏差过大,求得的反摩阻影响长度可超过精确值50%以上。

The rigorous formula for calculating the anchorage loss of post-tensioned curved prestressing tendon was derived by analyzing the tangential equilibrium condition of micro segment of tendon. The difference between friction effect and reverse-friction effect was revealed by comparing the magnitudes between the tendon stress increment and the friction loss in the length of reverse-friction effect. The approximation of the method for calculating anchorage loss in current bridge design codes in China was commented through numerical examples. The results show that the reverse-friction effect is smaller than the friction effect. The method for calculating anchorage loss in current railway bridge design code in China has higher precision, and the calculated value of the anchorage loss at ends of tendon is larger than the exact value. However, the calculated value does not exceed 10% of the exact value. The method for calculating anchorage loss in current highway bridge design code in China can cause excessive deviation and the calculated length of reverse-friction effect may exceed the exact value by more than 50%.