无粘结预应力筋的极限应力

在我国现行《无粘结预应力混凝土结构技术规程》（ＪＧＪ／Ｔ９２－９３）的建议公式基础上，结合国内外已有试验数据，提出了无粘结预应力筋极限应力计算公式，并结合概率和数理统计知识，对所提公式进行分析研究，证明了该公式具有一定保证率，可用于工程设计计算中；同时，还推荐了美国学者Ａ．Ｅ．Ｎａａｍａｎ等提出的无粘结预应力筋极限应力公式，该公式计算虽较为复杂，但有较高的计算精度。

Ultimate stress of unbounded prestressed tendons

The unbounded partial presstressed concrete members are easy to construct and have less prestress loss, so they have been extensively used at home and abroad. In the design of unbounded partial presstressed concrete members, the ultimate stress in the tendons has to be used. This article proposed an empirical expression for ultimate stress in tendons on the base of the exist test result, and verify this expression can be used in practice with the knowledge of reliability and statistics. A complex but accurate formulae for ultimate stress in tendons is recommended.