连续梁中无粘结预应力筋极限应力增量

无粘结筋极限应力增量的合理计算,是较准确计算无粘结预应力混凝土梁正截面承载力和极限荷载的基础。采用弯矩-曲率非线性分析法编制了可考察预应力混凝土梁中无粘结筋极限应力增量的计算程序,通过与16根两跨预应力混凝土连续梁中无粘结筋极限应力实测值的比较,验证了该方法的精确性。最后基于仿真分析结果,得到了预应力筋配筋指标、非预应力筋配筋指标、跨高比、加载形式等参数对承载能力极限状态下连续梁中无粘结筋应力增长的影响规律;建立了无粘结部分预应力混凝土连续梁中无粘结筋极限应力增量的计算公式。

METHOD FOR CALCULATING THE ULTIMATE STRESS INCREMENT IN UNBONDED TENDONS IN BEAMS

Reasonable calculation of ultimate stress increment in unbonded tendons is basis of calculating the resistance and ultimate load in unbonded prestressed continuous beams.Moment-curvature nonlinear analysis method was applied to compile the calculation programs of the ultimate stress increment in unbonded tendons in prestressed beams.Accuracy of the method was verified by compared with the tested results of ultimate stress in unbonded tendons in 16 two-span concrete continuous beams.Based on results of model examinations,law of some basic factors such as non-prestressed reinforcement index,prestressed reinforcement index,ratio of span to depth and loading type affecting stress increment of tendons in continuous beam are presented,and then calculation formulus of ultimate stress increment of tendons in unbonded prestressed concrete continuous beam are proposed.