高铁连续梁收缩徐变及长期挠度变化研究

Research on the Shrinkage and Creep and Changes of Long- term Deflection of High- speed Rail Continuous Beam

研究目的:高铁连续梁成桥后,随着时间的推移,由于收缩徐变的影响,连续梁的挠度会不断变化,影响收缩徐变的年相对湿度、加载龄期、收缩徐变系数等都会不同程度的影响桥梁的长期挠度。为研究混凝土的徐变与收缩对大跨度桥梁的变形和内力影响程度,选择逼近实际的徐变和收缩分析模式,合理地进行徐变、收缩效应分析从而正确地考虑徐变与收缩的影响非常必要。研究结论:(1)相对湿度减小,长期挠度增加,对保证成桥线形是不利的,因此增加相对湿度,如采用蒸汽养护等措施对桥梁的长度挠度有减小的作用,有利于保持桥梁的成桥线形;(2)桥梁的加载龄期较短,长期挠度也将有所增加,因此在施工过程中,限制施工荷载过早的加载于新浇筑梁段可以减低长期挠度;(3)徐变系数对桥梁的长期挠度产生很大影响,徐变系数增大,桥梁的长期挠度增加,选取适当的徐变系数对预测桥梁的长度挠度有着十分重要的作用,因此在重要性桥梁设计中,采取试验等措施确定徐变系数是必要的;(4)本研究结论对高铁连续梁的施工和预拱度的计算具有指导意义。

Research purposes： When continuous beam of high - speed railway is completed, with the passage of time, because of the influence of shrinkage and creep, continuous beam deflection will keep changing. The long - term deflection of the bridge will be affected in different degrees by relative humidity, loading age, shrinkage and creep coefficient. In order to study the influence of the creep and shrinkage of concrete on deformation and internal force of long span bridges, this paper chooses approach practical analysis pattern of creep and shrinkage, reasonably conducts analysis of creep and shrinkage effect, it is very necessary to properly think over the influence of shrinkage and creep. Research conclusions：（ 1 ） The relative humidity reducing, the long -term deflection increasing, are disadvantageous to ensure the bridge line, so increasing the relative humidity, such as the use of steam curing measures has a decreasing effect for the length of deflection of the bridge, is beneficial to keep the bridge line of the bridge. （2） The short loading age of the bridge will also increase long - term deflection, so in the construction process, limiting construction load early in the new pouring of beam section, can reduce the long- term deflection. （3） Creep coefficient has a great effect on the long- term deflection of the bridge, creep coefficient increases, the long- term deflection of the bridge increases, selecting the appropriate creep coefficient is pretty important for predicting the length of the deflection of the bridge, so it is necessary to determine the creep coefficient by taking the test measures in the design of important bridge. （4） This research conclusion has a guiding significance for the construction and pre - camber calculation for the high - speed railway continuous beam.