对用名义拉应力控制预应力混凝土受弯构件裂缝宽度方法的2点改进

在名义拉应力裂缝宽度控制方法中,分别引入预应力度λ的影响和预应力筋第2工作阶段对裂缝宽度控制的有利影响,分别推导了考虑预应力度影响的预应力筋用量计算公式和考虑预应力筋第2阶段有利影响的预应力筋用量计算公式。对某工程实例进行计算分析,结果表明,使用名义拉应力控制裂缝方法计算预应力筋用量时考虑预应力度λ的影响,可以使预应力混凝土结构的设计更加经济、合理。对简支梁的试算分析结果表明,用2种名义拉应力控制裂缝方法算得的预应力筋用量均比用规范方法计算所得的大,而考虑Ap第2阶段贡献后,计算结果与用规范方法计算所得结果接近。

Two pieces of improvement on the crack width control method using nominal tensile stress for prestressed concrete flexural member

Influence of prestress degree and prestressing tendon of the second working state were taken into account in the crack width control method using nominal tensile stress.Computing formula for prestressing tendon considering prestress degree and the formula considering prestressing tendon in second working state were both presented.Using these formulas,one example was calculated.The result shows that it can make the prestressed concrete structure designed more economical.The influences of prestress degree are considered when the prestressing tendon is calculated by the crack width control method using nominal tensile stress. Calculation of the simply supported beam shows that the prestressing reinforcement calculated by both improved crack width control method are more than that calculated by the code.While considering the influences of prestressing reinforcement in second working stats accounted,the prestressing reinforcement calculated is nearer to that calculated by the code.