随机变温作用下徐变对预应力混凝土梁桥结构行为的影响

发布时间：2018-05-27 05:28

  本文选题：桥梁工程 + 徐变效应分析　； 参考：《公路交通科技》2017年12期

【摘要】：结合在自然环境条件下开展徐变试验和既有研究成果,对现有可考虑温度影响的徐变模型包括Fahmi提出的基于时间-温度等效原理的徐变模型、CEB-FIP(1990)模型、BP模型、B3模型和组合徐变模型进行比选,并将比选出的组合徐变模型应用于预应力混凝土梁桥的徐变效应分析中。假定徐变符合弹性徐变理论,基于初应变法解决了应用组合徐变模型进行桥梁结构徐变效应分析的问题。通过将基于组合徐变模型和依据我国公路04桥规分析得到的桥梁结构变形、应力和预应力损失结果进行比较,探究忽略实际变温对徐变影响可能导致的桥梁结构行为估算偏差。研究结果表明:考虑实际环境变温影响的徐变系数预测值与试验值更为贴近,现行徐变模型因未计入环境变温影响,可能低估了冬季和春季浇注混凝土的徐变,高估了夏季和秋季浇注混凝土的徐变;在考虑自然环境温度影响的徐变作用下,梁体下挠度可较规范值大约15.5 mm,截面应力与规范值的最大相对偏差约为10%,预应力损失可较规范值大约40%以上。随机变温作用下混凝土徐变,加剧了桥梁梁体持续下挠、混凝土开裂和预应力损失等问题。因此,在桥梁结构设计中推荐采用组合徐变模型计入实际环境变温对结构混凝土徐变行为的影响,从而为预应力束的合理布置与张拉控制、梁体预拱度的准确设置等方面提供参考。
[Abstract]:Combined with the research results of creep test under natural environment, The existing creep models which can take into account the influence of temperature, including the creep model based on the time-temperature equivalence principle proposed by Fahmi (CEB-FIP / 1990), are compared with the BP model / B3 model and the combined creep model. The combined creep model selected by comparison is applied to the analysis of creep effect of prestressed concrete beam bridge. Assuming that creep is in accordance with elastic creep theory, the problem of applying combined creep model to analyze creep effect of bridge structure is solved based on initial strain method. By comparing the results of deformation, stress and prestress loss of bridge structure based on combined creep model and the analysis of highway 04 bridge gauge in China, this paper explores the estimated deviation of bridge structure behavior caused by neglecting the influence of actual temperature on creep. The results show that the predicted value of creep coefficient considering the effect of actual environmental temperature change is closer to the experimental value, and the current creep model may underestimate the creep of pouring concrete in winter and spring because it does not take into account the influence of environmental temperature change. The creep of cast concrete in summer and autumn is overestimated. The deflection under the beam can be about 15.5 mm higher than the standard value, the maximum relative deviation between the cross section stress and the normal value is about 10 mm, and the loss of prestress can be more than 40% than the normal value. Under the action of random temperature, the creep of concrete intensifies the problems of continuous deflection, cracking of concrete and loss of prestress. Therefore, in the design of bridge structure, it is recommended that the combined creep model be used to take into account the influence of temperature change in the actual environment on the creep behavior of the structure concrete, so that the reasonable arrangement and tension control of the prestressing beam can be achieved. The accurate setting of beam pre-arch is provided as a reference.
【作者单位】： 西南交通大学土木工程学院;
【基金】：国家自然科学基金项目(51508474) 铁道部科技研究开发计划重大课题项目(2008G031-K)
【分类号】：U441;U448.35
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本文编号：1940646