考虑开裂非协调变形的PC梁承载力

Load Bearing Capacity for PC Girders with Consideration of Crack-induced Incompatible Deformation

为了解裂缝扩展对PC梁体承载能力影响,基于理论分析提出了考虑开裂非协调变形的PC梁体承载能力分析方法,同时开展了该方法与传统应变协调法和模型梁试验结果的对比研究,并进一步研究了开裂非协调变形对预应力筋应力增量和梁体混凝土受压区高度的影响规律。结果表明:与传统应变协调法相比,开裂非协调变形对预应力筋应力增量的影响在屈服阶段达10.2%,在极限阶段达7.6%,非协调变形对极限承载能力和受压区混凝土高度的影响均超过5%,对极限挠度的影响为10%,进行PC结构承载能力分析时有必要考虑开裂非协调变形的影响。

In order to learn the influence of crack propagation on load bearing capacity （LBC） for prestressed concrete （PC） girders, an analytical method of LBC for PC girders with consideration of crack-induced incompatible deformation （CID） was proposed based on theoretical analysis. Meanwhile comparative study was carried out among the results produced by traditional strain compatibility method, model beam tests and the proposed method. The effect laws of CID on both stress increments of prestressed tendons and the depths of the compressive region were further investigated. The results show that comparing to the traditional method, the effect of CID on stress increments of prestressed tendons reaches 10. 2% and 7. 6% for yielding and ultimate states, respectively. Its effects on ultimate LBC and depth of the concrete compressive region excel 5% with its effect on ultimate deflection of about 10%. These indicate that it is necessary to take CID influence into account in LBC analysis for PC girders.