截面收缩徐变非一致性分布与T梁桥腹板竖向开裂的时变相关性

发布时间：2018-10-15 09:32

【摘要】：在钢筋混凝土或预应力混凝土T梁桥的腹板竖向裂缝中,有一些并非在施工时出现,而是在长达1-2 a后才逐渐出现。为解释这些T梁桥腹板竖向裂缝形成过程中具有时间依赖性的现象,研究了截面收缩、徐变不一致分布与T梁竖向开裂的相关性。根据T梁截面的特点,考虑结构截面不同部位实际的配筋与理论厚度对收缩、徐变的不同影响。根据轴力等效转换及截面钢筋和混凝土变形协调的原则,推导了钢筋对收缩、徐变应变影响的理论系数,采用截面分层的方法考虑截面理论厚度沿梁高的变化,最后依据截面应变的平截面假定,推导了T梁截面收缩、徐变非一致分布效应导致的截面收缩、徐变自应力及其随时间变化的分层计算方法。实桥参数计算结果表明,T梁梁体纤薄,其顶板、腹板和马蹄的配筋和理论厚度存在较大差异,收缩、徐变在截面上容易形成不同步或差异较大的不一致分布情况。T梁截面收缩、徐变非一致分布是导致腹板竖向裂缝具有时间依赖性的重要因素,利用本文方法得到的竖向裂缝在时间轴上的形成过程与实际桥梁的裂缝出现的时间和位置情况基本吻合,验证了本文方法的有效性,为结构设计中考虑此因素提供了理论工具。
[Abstract]:In the vertical cracks in the web of reinforced concrete or prestressed concrete T-beam bridge, some of them do not appear during construction, but only gradually appear after 1-2 years. In order to explain the time-dependent phenomena in the formation of vertical cracks in the webs of T-beam bridges, the correlation between cross-section shrinkage, creep and vertical cracking of T-beams is studied. According to the characteristics of T-beam section, different effects of actual reinforcement and theoretical thickness on shrinkage and creep of different parts of structure section are considered. According to the principle of equivalent transformation of axial force and coordination of section reinforcement and concrete deformation, the theoretical coefficients of the effect of reinforcement on shrinkage and creep strain are derived, and the variation of theoretical thickness of section along the height of beam is considered by the method of section stratification. Finally, according to the assumption of cross-section strain, the paper deduces the method of calculating the cross-section shrinkage, creep self-stress and its variation with time caused by cross-section shrinkage, non-uniform distribution effect of creep, and the delamination calculation method of T-beam. The calculation results of the real bridge parameters show that the T-beam is thin, and the reinforcement and theoretical thickness of its roof, web plate and horseshoe are different. The non-uniform distribution of creep is an important factor leading to the time-dependent vertical cracks in web plates. The formation process of vertical cracks on the time axis obtained by the method in this paper is basically consistent with the time and position of the cracks in the actual bridges. The validity of this method is verified and a theoretical tool is provided for the consideration of this factor in structural design.
【作者单位】：交通运输部公路科学研究院;
【基金】：云南省交通运输厅科技计划(云交科教20161632)
【分类号】：U441.5

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