薛伟辰  王  骅　（同济大学建筑工程系  上海　200092）

[提要]  对国内外有关钢－混凝土组合梁体外预应力筋极限应力的研究成果进行了较为系统的综述。根据近期完成的4根体外预应力钢－混凝土组合梁单调全过程试验，提出了体外预应力筋预应力损失的设计建议。基于虚功原理和变形协调条件分别推导了体外预应力筋弹性增量和极限应力的计算公式，在此基础上建立了体外预应力钢－混凝土组合梁抗弯承载力的计算公式，并编制了计算程序，程序计算值与试验结果吻合良好。
[关键词]  体外预应力  钢－混凝土组合梁  预应力损失  极限应力  抗弯承载力

The existing research achievements, at home and abroad, on ultimate stress of external tendons in the prestressed　steel-concrete composite beams are systematically summarized. On the basis of experiments of four prestressed steel-concrete composite beams under monotonous loads, prestressing loss of external tendons is studied and the corresponding design suggestions are put forward. Based on the principle of virtual principle and compatibility between the deformations of the composite beam and the tendons,a formula is developed for calculating elastic increment and ultimate
increment of external tendons. Design equations, capable of calculating flexural capacity of　prestressed steel-concrete composite beams, are derived after taking into account the prestressed stress increments, and the corresponding program is developed. The calculations by the program are in good agreement with test results.
Keywords:  external prestressing; steel-concrete composite beams; prestressing loss; ultimate stress; flexural capacity

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