预应力混凝土简支梁板中无粘结筋应力增长规律

Law of stress increment in unbonded tendons for concrete simple beams and slabs

针对无粘结预应力混凝土梁板在受荷过程中的无粘结筋不符合变形平截面假定的特点,应用等刚度法及弯矩-曲率非线性分析法,编制了可用于分别考察正常使用极限状态和承载能力极限状态无粘结筋应力增长规律的计算程序。基于模型试验结果和大量仿真分析结果,得到了非预应力筋配筋指标、预应力筋配筋指标、跨高比、加载形式、预应力筋布筋型式、跨中预应力筋合力点至受压区边缘的距离等参数对正常使用阶段及正截面承载能力极限状态下简支梁板中无粘结筋应力增长的影响规律;建立了无粘结预应力混凝土简支梁板中无粘结筋在正常使用阶段和正截面承载能力极限状态下应力增量的计算公式。

Because the plane-section assumption is not applicable to tendon in unbonded prestressed concrete beams and slabs under loading, the constant stiffness method and moment-curvature nonlinear analysis method were used to compile the calculation programs of the law with serviceability and ultimate carrying capacity. Based on results of the model experiment and a large number of simulations analysis, the law of some basic factors such as non-prestressed reinforcement index fl,, prestressing reinforcement index βp, ratio of span to depth l/h, loading type, distribution of prestressed reinforcements and depth from concrete extreme fiber to centroid of the prestressing steels hp affecting stress increment of tendons in simple beams and slabs were presented, and then calculation formulus of stress increment of tendons at serviceability and ultimate carrying capacity state in unbonded prestressed concrete beams and slabs were proposed.