单索面宽斜拉桥主梁早期裂缝成因分析
发布时间：2018-12-06 22:10
【摘要】：近年来，随着经济的发展和城市建设的不断扩展，桥梁的跨径在不断的增大，桥梁形式也变得多种多样，普通的桥型已经无法满足人们的省美以及使用要求，各种大跨径新型桥梁不断的被应用于城市桥梁的建设，单索面宽箱梁斜拉桥作为一种新型桥梁，既满足了城市建设美观上的需要，又满足了城市交通量不断增大需要，同时还满足了跨越能力的需要。然而设计理论的不完美以及施工质量的缺陷等各方面的因素，使得单索面宽箱梁斜拉桥很容易在施工过程中产生裂缝，而裂缝的出现对于桥梁结构的受力以及使用是相当不利的，所以，对单索面宽箱梁斜拉桥早期裂缝成因的分析，对于设计以及施工都是十分有必要的。 本文以重庆双碑嘉陵江大桥（主跨330米，，箱梁宽32.5米，单索面宽箱梁斜拉桥）为工程背景，该桥在零号块二次浇筑时，在箱梁的底板、翼缘板及横隔板上产生了大量的裂缝，不仅影响桥梁的美观，同时影响桥梁的施工及后期的运营使用，因此本文针对该桥在施工零号块时底板、翼缘板、横隔板出现裂缝的现象展开研究分析。 本文首先对单索面宽箱梁斜拉桥的特点进行了一个阐述，对国内外关于桥梁裂缝的分析研究现状做了一个介绍；然后对重庆双碑嘉陵江大桥零号块的裂缝分布情况进行了一个描述，并对桥梁裂缝的产生原因进行了浅要分析；最后分别对自重及索力作用下的效应、预应力及挂篮作用下的效应、混凝土横向收缩效应对主梁的影响、温度效应对主梁的影响进行计算。在自重及索力作用的计算中， 通过对各种影响因素的计算结果进行研究分析，对比桥梁裂缝分布的实际情况，总结出裂缝集中部位的裂缝比率，从而得知各部位裂缝的成因以及引起开裂的主要因素。从各个因素的分析结果来看，温度效应是引起主梁混凝土开裂的主要因素，温度在水化热过程产生了热量从而使混凝土温度升高，混凝土温度升高到一定程度后水化热的产热与混凝土的散热达到平衡，之后便开始降温，降温引起混凝土的收缩，因此在混凝土初凝的早期便产生了裂缝。其次收缩是引起主梁混凝土开裂的又一重要因素，新老混凝土的浇筑时间相距过长，使得新浇筑混凝土与老混凝土的收缩速度差距过大，从而约束了新混凝土的变形而产生了裂缝，并且随着时间的推移，裂缝仍然在发展。
[Abstract]:In recent years, with the development of economy and the continuous expansion of urban construction, the span of bridges has been increasing, and the forms of bridges have become various. All kinds of long-span new bridges are used in the construction of urban bridges. As a new type of bridge, the cable-stayed bridge with single cable plane and wide box girder meets not only the aesthetic needs of urban construction, but also the increasing demand of urban traffic volume. At the same time, it also meets the need of leapfrogging ability. However, because of the imperfection of design theory and the defects of construction quality, it is easy to produce cracks in the construction process of cable-stayed bridge with wide box girder with single cable plane. However, the occurrence of cracks is quite unfavorable to the force and use of bridge structure. Therefore, it is necessary for design and construction to analyze the causes of cracks in the early stage of cable-stayed bridge with wide box girder with single cable plane. This paper takes the Chongqing Shuangbei Jialing River Bridge (main span 330 meters, box girder 32.5 meters wide, single cable plane wide box girder cable-stayed bridge) as the engineering background. There are a lot of cracks on the flange plate and the transverse spacer, which not only affect the beauty of the bridge, but also affect the construction of the bridge and the operation of the bridge later. Therefore, this paper aims at the bottom plate and flange plate of the bridge in the construction of zero block. The phenomenon of cracks in the transverse diaphragm is studied and analyzed. In this paper, the characteristics of cable-stayed bridge with wide box girder with single cable plane are described, and the analysis and research status of bridge cracks at home and abroad is introduced. Then it describes the distribution of cracks in block zero of Shuangbei Jialing River Bridge in Chongqing, and analyzes the causes of the cracks in the bridge. Finally, the effects of deadweight and cable force, the effect of prestress and hanging basket, the effect of transverse shrinkage of concrete on the main beam and the effect of temperature on the main beam are calculated respectively. In the calculation of deadweight and cable force, by studying and analyzing the calculation results of various influencing factors, comparing the actual situation of bridge crack distribution, the crack ratio of the concentrated part of crack is summarized. Thus, the causes of the cracks and the main factors causing the cracks are known. From the analysis results of various factors, the temperature effect is the main factor that causes the cracking of the main beam concrete, and the temperature produces heat in the hydration heat process, which makes the concrete temperature rise. When the temperature of concrete rises to a certain extent, the heat production of hydration heat reaches equilibrium with the heat dissipation of concrete, and then it begins to cool down, which causes the shrinkage of concrete, so cracks occur in the early stage of concrete initial setting. Secondly, shrinkage is another important factor that causes cracking of main beam concrete. The pouring time of new and old concrete is too long, which makes the gap of shrinkage speed between new and old concrete too large. Therefore, the new concrete deformation is restrained and cracks are produced, and the cracks are still developing over time.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.27
本文编号：2366735
[Abstract]:In recent years, with the development of economy and the continuous expansion of urban construction, the span of bridges has been increasing, and the forms of bridges have become various. All kinds of long-span new bridges are used in the construction of urban bridges. As a new type of bridge, the cable-stayed bridge with single cable plane and wide box girder meets not only the aesthetic needs of urban construction, but also the increasing demand of urban traffic volume. At the same time, it also meets the need of leapfrogging ability. However, because of the imperfection of design theory and the defects of construction quality, it is easy to produce cracks in the construction process of cable-stayed bridge with wide box girder with single cable plane. However, the occurrence of cracks is quite unfavorable to the force and use of bridge structure. Therefore, it is necessary for design and construction to analyze the causes of cracks in the early stage of cable-stayed bridge with wide box girder with single cable plane. This paper takes the Chongqing Shuangbei Jialing River Bridge (main span 330 meters, box girder 32.5 meters wide, single cable plane wide box girder cable-stayed bridge) as the engineering background. There are a lot of cracks on the flange plate and the transverse spacer, which not only affect the beauty of the bridge, but also affect the construction of the bridge and the operation of the bridge later. Therefore, this paper aims at the bottom plate and flange plate of the bridge in the construction of zero block. The phenomenon of cracks in the transverse diaphragm is studied and analyzed. In this paper, the characteristics of cable-stayed bridge with wide box girder with single cable plane are described, and the analysis and research status of bridge cracks at home and abroad is introduced. Then it describes the distribution of cracks in block zero of Shuangbei Jialing River Bridge in Chongqing, and analyzes the causes of the cracks in the bridge. Finally, the effects of deadweight and cable force, the effect of prestress and hanging basket, the effect of transverse shrinkage of concrete on the main beam and the effect of temperature on the main beam are calculated respectively. In the calculation of deadweight and cable force, by studying and analyzing the calculation results of various influencing factors, comparing the actual situation of bridge crack distribution, the crack ratio of the concentrated part of crack is summarized. Thus, the causes of the cracks and the main factors causing the cracks are known. From the analysis results of various factors, the temperature effect is the main factor that causes the cracking of the main beam concrete, and the temperature produces heat in the hydration heat process, which makes the concrete temperature rise. When the temperature of concrete rises to a certain extent, the heat production of hydration heat reaches equilibrium with the heat dissipation of concrete, and then it begins to cool down, which causes the shrinkage of concrete, so cracks occur in the early stage of concrete initial setting. Secondly, shrinkage is another important factor that causes cracking of main beam concrete. The pouring time of new and old concrete is too long, which makes the gap of shrinkage speed between new and old concrete too large. Therefore, the new concrete deformation is restrained and cracks are produced, and the cracks are still developing over time.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.27
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