混凝土箱形结构温度梯度模式研究
发布时间：2018-10-09 18:54
【摘要】：混凝土开裂严重影响桥梁结构耐久性的和安全性,温差拉应力是造成混凝土箱形结构开裂的主要因素之一,而合理的温差分布模式是准确计算温差应力的基础,但目前有关箱形墩及鱼腹形箱梁温度作用的研究较少,因此对混凝土桥梁结构温差效应进行深入的探讨和研究是必要的。本文依托实际工程项目,基于现场温度作用实测结果及参数分析,对混凝土箱形结构温度作用进行了研究,主要内容如下:(1)根据混凝土箱形墩日照作用连续观测结果,总结了其日照温度场及温度效应的变化规律;基于参数分析结果,讨论了壁面方位角对日照正温差分布的影响,并计算了不同温差分布模式下的温差效应,据此确定了不同朝向箱形墩日照正温差分布模式。分析结果表明:墩壁朝向不同,最大温差出现时刻有差别,墩壁达到的最大温差值也不同,壁面方位角与温差最大值的关系近似为正弦函数分布。(2)基于混凝土箱形墩寒流降温作用下的连续观测结果及温度场和温致效应的参数分析,研究了降温速率、降温幅度和壁厚变化对温差分布的影响,确定了不同壁厚箱形墩负温差分布模式。结果表明:寒流降温作用下,混凝土箱形墩各侧温差分布基本一致;壁厚不同的箱形墩,其温差分布模式不同;在相同降温幅度下,降温时刻的初始温度分布对箱形墩降温过程中的结构反应增量影响较小;对壁厚0.6m的箱形墩,大气降温20℃所导致负温差产生的横向拉应力可达3.6MPa,应引起足够的重视。(3)基于鱼腹形箱梁瞬态温度场的分析结果提出了其日照温差计算模式,并对三跨连续箱梁桥的空间温度效应进行了分析,与采用现行公路桥规温差模式的计算结果进行了对比。结果表明:横向温差对鱼腹形箱梁最大横向拉应力的影响很小,可忽略横向温差的影响;现行公路桥规采用的折线形竖向温差梯度模式与实际箱梁温度分布有较大差别,导致对温度效应的考虑不足,建议在设计中采用指数函数形式的竖向温差梯度模式。
[Abstract]:Concrete cracking seriously affects the durability and safety of bridge structure. Temperature differential tensile stress is one of the main factors that cause concrete box structure cracking, and reasonable temperature difference distribution model is the basis of accurate calculation of temperature differential stress. However, there are few researches on the temperature effects of box piers and fish-bellied box girders, so it is necessary to study the effect of temperature difference of concrete bridges. Based on the actual project, the temperature effect of concrete box structure is studied based on the measured results of field temperature and parameter analysis. The main contents are as follows: (1) according to the continuous observation results of sunshine action of concrete box pier, Based on the results of parameter analysis, the effect of wall azimuth on the distribution of positive temperature difference of sunlight is discussed, and the effect of temperature difference under different temperature distribution modes is calculated. According to this, the distribution model of normal temperature difference of sunshine in different directions of box pier is determined. The results show that the maximum temperature difference is different with the direction of the pier wall, and the maximum temperature difference value of the pier wall is also different. The relationship between the wall azimuth and the maximum temperature difference is approximately a sinusoidal function distribution. (2) based on the continuous observation results of the cold current of concrete box pier and the parameter analysis of temperature field and temperature effect, the cooling rate is studied. The negative temperature difference distribution mode of box pier with different wall thickness is determined by the influence of temperature drop range and wall thickness on the temperature difference distribution. The results show that the temperature difference distribution of concrete box pier is basically the same, the temperature difference distribution mode of box pier with different wall thickness is different, and under the same cooling range, the temperature difference distribution of concrete box pier is basically the same. The initial temperature distribution at the cooling time has little effect on the increment of structural response in the cooling process of the box pier, and on the box pier with a wall thickness of 0.6 m. The transverse tensile stress caused by negative temperature difference due to 20 鈩，
本文编号：2260410
[Abstract]:Concrete cracking seriously affects the durability and safety of bridge structure. Temperature differential tensile stress is one of the main factors that cause concrete box structure cracking, and reasonable temperature difference distribution model is the basis of accurate calculation of temperature differential stress. However, there are few researches on the temperature effects of box piers and fish-bellied box girders, so it is necessary to study the effect of temperature difference of concrete bridges. Based on the actual project, the temperature effect of concrete box structure is studied based on the measured results of field temperature and parameter analysis. The main contents are as follows: (1) according to the continuous observation results of sunshine action of concrete box pier, Based on the results of parameter analysis, the effect of wall azimuth on the distribution of positive temperature difference of sunlight is discussed, and the effect of temperature difference under different temperature distribution modes is calculated. According to this, the distribution model of normal temperature difference of sunshine in different directions of box pier is determined. The results show that the maximum temperature difference is different with the direction of the pier wall, and the maximum temperature difference value of the pier wall is also different. The relationship between the wall azimuth and the maximum temperature difference is approximately a sinusoidal function distribution. (2) based on the continuous observation results of the cold current of concrete box pier and the parameter analysis of temperature field and temperature effect, the cooling rate is studied. The negative temperature difference distribution mode of box pier with different wall thickness is determined by the influence of temperature drop range and wall thickness on the temperature difference distribution. The results show that the temperature difference distribution of concrete box pier is basically the same, the temperature difference distribution mode of box pier with different wall thickness is different, and under the same cooling range, the temperature difference distribution of concrete box pier is basically the same. The initial temperature distribution at the cooling time has little effect on the increment of structural response in the cooling process of the box pier, and on the box pier with a wall thickness of 0.6 m. The transverse tensile stress caused by negative temperature difference due to 20 鈩，
本文编号：2260410
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