预应力混凝土连续箱梁不同布索方式对比分析

Analysis of Different Tendon Layout Types for PC Continuous Box Girder

从理论上对比分析了不同布索方式的优缺点,以某预应力混凝土连续箱梁桥为原型,通过数值计算对比分析了预应力损失对不同布索方式箱梁腹板主拉应力的影响。结果表明,在理论上取消下弯索,通过适当调整顶、底板索和竖向预应力筋来实现对腹板主拉应力控制是可行的;适当调整竖向预应力的大小,竖向+纵向布索方式混凝土强度提高系数优于下弯索布索方式;竖向预应力损失对竖向+纵向布索方式预应力混凝土箱梁腹板主拉应力的影响非常敏感,在实际工程中,竖向预应力损失50%后,竖向+纵向布索方式预应力混凝土箱梁腹板主应力的分布将劣于下弯索布索方式。

The merits and faults of different types of tendon layout was discussed from theory point of view. Took a PC continuous box girder bridge as an example, the influence of the prestress loss on web principal tensile stress of different tendon layout types for PC box girder was analyzed by FEM methods. The result shows that （1） it is feasible to control web principal tensile stress without down-curved tendon by adjusting the top tendon, bottom tendon and vertical prestress tendon in theory; （2） the concrete strength improving coefficient with vertical prestress and longitudinal tendon is better than that with down-curved tendon by adjusting the vertical prestress properly; （3） web principal tensile is influenced by the vertical prestress loss sensitively, the concrete web principal stress with vertical prestress and longitudinal tendon is inferior to that with down-curved tendon in the condition that 50% vertical prestress loss.