基于裂缝特征统计参数的箱梁桥安全性能评估

发布时间：2018-04-19 08:50

本文选题：预应力混凝土箱梁 + 裂缝特征统计参数　；参考：《长安大学》2015年硕士论文

【摘要】：在现役桥梁类型中最常见的就是预应力混凝土箱梁桥,其随着运营时间的增加,在外荷载的反复作用以及主梁钢束预应力损失等因素的影响下,主梁便会出现不同程度上的裂缝以及变形等病害。所以定期对桥梁做外观检测也成为对其加固和养护的必要前提。对主梁裂缝特征参数进行统计也是其中的一项重要指标。怎样通过桥梁的外观检查得出的裂缝特征参数统计值来评估该桥梁在运营阶段的安全性能具有十分重要的现实意义,同时也是本文主要的研究方向。本文主要把纵向钢束预应力损失当作主梁底板开裂的主要原因,并以受弯混凝土梁段开裂后截面受压区高度的计算方法作为理论基础,通过对开裂箱梁底板横向裂缝特征参数的统计,推导出开裂的箱梁截面特征值的计算公式。再考虑钢束和混凝土之间由于相互作用而产生的应变差,进而计算出开裂截面同一水平面上钢束应力均值,并将其近似的作为这一层钢束中每根钢筋的有效预应力值。通过纵向钢束预应力实际分布值预测方法,并对其中的预测方法加以简化,将其应用在开裂后的箱梁桥中,并通过实例对比分析证明此方法的正确性。通过对运营中某实桥的外观检查,对检查得出的裂缝特征参数进行了统计,运用上述的模拟预测方法,调整预应力钢束的参数值来模拟和预测桥梁的运营状况,通过对其不同运营时间里主梁应力和挠度值的分析对比情况来评估该桥的安全性能,并相应的提出一些加固和养护措施。
[Abstract]:The most common type of bridge in active service is prestressed concrete box girder bridge. With the increase of operation time, the repeated action of external load and the loss of prestressing force of main girder, etc.The main beam will appear in varying degrees of cracks and deformation and other diseases.Therefore, regular inspection of the bridge appearance has become a necessary prerequisite for its reinforcement and maintenance.Statistical analysis of crack characteristic parameters is also an important index.How to evaluate the safety performance of the bridge through the statistical value of crack characteristic parameters obtained from the exterior inspection of the bridge is of great practical significance and is also the main research direction of this paper.In this paper, the prestress loss of longitudinal steel bundle is regarded as the main reason for the cracking of the main beam bottom slab, and the calculation method of the height of the section compression zone after cracking of the flexural concrete beam is taken as the theoretical basis.Based on the statistics of transverse crack characteristic parameters of cracked box girder bottom plate, the formula for calculating the cross section characteristic value of cracked box girder is derived.Considering the strain difference between the steel beam and concrete due to the interaction, the stress mean value of the steel beam on the same horizontal plane of the cracking section is calculated, which is approximately regarded as the effective prestress value of each steel bar in this layer of steel bundle.The prediction method of the actual distribution value of longitudinal steel prestress is simplified and applied to the cracked box girder bridge, and the correctness of the method is proved by the comparison and analysis of an example.By checking the appearance of a real bridge in operation, the crack characteristic parameters obtained from the inspection are statistically analyzed, and the parameters of prestressed steel bundle are adjusted to simulate and predict the operation condition of the bridge by using the above-mentioned simulation and prediction method.The safety performance of the bridge is evaluated by analyzing and comparing the stress and deflection of the main girder in different operation time, and some reinforcement and maintenance measures are put forward accordingly.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.213;U447

【参考文献】