预应力混凝土受弯构件长期反拱和挠度的合理估算方法  

Rational method for estimating long-term camber and deflection of prestressed concrete flexure members

作　　者：徐金声[1] 薛立红[1] 

机构地区：[1]中国建筑科学研究院,北京100013

出　　处：《建筑结构》2011年第1期95-102,110,共9页Building Structure

摘　　要：回顾了对预应力混凝土构件长期反拱变化规律的研究及认识过程;提出了一个经验公式,大大简化了预应力混凝土构件长期反拱的精确计算工作。该经验公式既能适用于"全"预应力,也能适用于"部分"预应力混凝土构件长期反拱值的计算。同时,对预应力混凝土构件长期挠度的估算也提出了一个经验公式。长期反拱和挠度的两个经验公式都考虑了四个主要影响因素作为自变量(即钢筋的配筋率及其位置与混凝土的徐变和收缩)。用试验数据全面地进行了对比,给出长期反拱系数θp(t→∞)的终极值的可变范围为-3～+3.5,其通常变动范围是-0.5～+2.8,而不是固定的值+2.0。长期挠度也不能简单地简化为短期挠度的2倍。给出了实际工程的检测结果和计算例题并提出了对现行《混凝土结构设计规范》第8.2.5条和第8.2.6条的修改建议。The historical understanding of long-term camber and deflection of prestressed concrete members was described.An empirical formula,which greatly simplifies the calculation for long-term camber of prestressed concrete members was presented.It not only applies to the calculation of long-term camber in prestressed concrete members,but also in partial-prestressed concrete members.An empirical formula for estimating long-term deflection was presented.The two empirical formulas of long-term camber and deflection had considered four important independent variables（steel ratio and its position,creep and shrinkage of concrete）.A comprehensive comparison of experimental data of long-term camber and results predicted by the formula was also carried out.The range of variation of long-term camber coefficient θp（t→∞） is-3 to ＋ 3.5,its normal range is-0.5 to ＋ 2.8 and not a constant value ＋ 2.0.Even long-term deflection cannot be simplified with a multiplication factor of 2 over short-term deflection.Suggestions were presented for revisions of section 8.2.5 and 8.2.6 of Code for design of concrete structures.

关 键 词：预应力混凝土 长期反拱系数 长期挠度系数 试验数据 经验公式 非预应力筋 配筋率 钢筋位置 

分 类 号：TU378[建筑科学—结构工程]