（中国建筑科学研究院工程抗震研究所，北京 100013）
［摘要］在超大跨度预应力梁设计时，为增加跨中区段预应力筋主弯矩的作用，通常将预应力筋布置为直线和抛物线的组合线形。研究表明，这种组合线形不能按等效荷载法来计算预应力的作用，而应采用约束次弯矩法来计算。推导了该种组合线形产生的约束次弯矩的计算公式，可方便运用到工程设计中，从而提高预应力的计算精度。
［关键词］直线和抛物线组合线形；约束次弯矩法；等效荷载法；次弯矩
Analysis of prestressing action caused by the combination form of line and parabola
Rong Weisheng(Institute of Earthquake Engineering, China Academy of Building Research, Beijing 100013, China)
Abstract:In order to increase primary moments in the middle sections of the span, the combination form of line and parabola is usually laid in the design of prestressed beams with great spans. Researches show that the equivalent load method couldn′t be used to calculate the prestressing action in the combination form, but the method of restraining secondary moments should be used. Formulae of restraining secondary moments caused by the combination form are presented for engineering design, and they can improve precision of prestressed structure design.
Keywords:combination form of line and parabola; method of restraining secondary moments; equivalent load method; secondary moment
作者简介：荣维生，工学博士，高工，Email:rongweisheng@sina.com。
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