[提要]  后张法预应力混凝土折线形屋架翻身扶直时，下弦产生较大平面外弯曲。从理论和实践两方面分析了屋架下弦产生侧向大变形的各种原因和决定性因素，并提出侧向挠度的计算方法、解决问题的途径和措施。
[关键词]  预应力  折线形屋架  平面外刚度  施工措施

The lower member of post-tensioning prestressed concrete roof truss has very large out-of-plane bending deformation when the folded roof truss stands up with supports. Pased on rational analysis of various main factors and experience, the calculating method of out-of-plane bending displacement and solving measures on construction are presented.
Keywords: folded roof truss; out-of-plane deformation; construction measures