全预应力混凝土梁的长期变形计算

Calculation of Long-term Deformations of Full PC Beams

关于全预应力混凝土梁长期变形的设计计算问题,现行TB10002.3—99《铁路桥涵钢筋混凝土和预应力混凝土结构设计规范》中尚无明确条款。对此,基于大型商用软件SOFISTIK的计算结果,重点研究了预应力度、混凝土强度等级以及综合配筋指标等设计参数对全预应力混凝土梁长期变形的影响,指出按《公路钢筋混凝土及预应力混凝土桥涵设计规范(2002送审稿)》和现行GB50010-2002《混凝土结构设计规范》的计算结果偏于不安全。提出了全预应力混凝土梁的长期变形增长系数需按混凝土龄期分时段取值的设计建议。

In the calculation of long-term deformation of full PC beams, there are no corresponding guidelines in the current Chinese ＂Code for Design on Reinforced and Prestressed Concrete Structures of Railway Bridges and Culverts＂ （TB 10002.3-- 99）. To solve this problem, by using a commercial FEM program （SOFISTIK）, the effects of several design parameters on the long-term deformations of full PC beams are calculated, including PPR, concrete strength and comprehensive index β0 of reinforcements. The results show that the long-term deformations are unsafely evaluated in the current Chinese Codes： ＂Specifications for Design of Reinforced Concrete and Prestressed Concrete Highway Bridge and Highway （submitted for checking, 2002 ）＂ and ＂Code for Design of Concrete Structures （GB50010- 2002）＂. This paper argues that the long-term de formation factors shall be acquired according to the age of con- crete, and some corresponding design suggestions be accepted.