预应力混凝土箱梁桥裂缝数值分析及控制研究

发布时间：2018-05-01 12:42

本文选题：预应力混凝土箱梁 + 裂缝　；参考：《重庆交通大学》2015年硕士论文

【摘要】：近年来,随着交通事业的迅猛发展,我国桥梁建设水平已迈上新台阶。预应力混凝土箱梁桥因截面抗弯、抗扭刚度大,施工方便,造价低廉等优势而颇具竞争力,该桥型近些年无论在规模还是跨径方面都取得了较大突破,但随之而产生的问题也越来越多,其中开裂问题在已建或在建工程中均较为普遍。在建工程中出现开裂问题会影响后续施工的质量与安全,使结构存在缺陷并埋下隐患,而已建成桥梁出现裂缝不仅影响结构美观,同时对结构的安全性及耐久性均构成较大的威胁,因此有必要对混凝土箱梁开裂问题进行系统深入的研究,探索产生这一病害的根本缘由。本文以广元市江口嘉陵江大桥为研究背景并结合现场实际情况,对预应力混凝土箱梁桥裂缝的影响因素展开研究,具体工作内容归纳如下:①通过查阅大量关于预应力混凝土箱梁桥开裂的书籍和相关文献,对此类问题有了一定的认知,并通过总结分析,得到了裂缝的成因、分布特点及力学特征,以指导后续工作更好地开展。②通过有限元分析,结合我国现行规范得到了竖向温度梯度对桥梁受力的影响规律,并对比分析了最不利温度梯度效应与活载效应关系,说明了温度梯度对桥梁受力影响很大;同时选取另外两种外国规范,计算分析后发现:三种规范下的温度梯度效应相差较大,因此在气候环境或工程背景特殊的情况下,应对现场温度观测,得到更为准确的温度效应。③通过计算分析顶、底板纵向预应力损失对全桥纵向应力的影响规律,得出其最不利影响区间,为以后工程设计提供有益参考。④运用ANSYS大型通用有限元分析模拟箱梁裂缝实际分布位置,并通过计算分析发现:在纵向预应力筋正常工作的情况下,竖向预应力损失过大和腹板尺寸设计不合理是引起箱梁腹板产生裂缝的主要原因。⑤通过对裂缝的成因、分布位置、影响因素等方面分析研究,从纵、竖向预应力的改进、合理配筋、箱梁尺寸、温度效应、施工工艺等方面提出了箱梁裂缝控制措施,并针对不同裂缝提出了对应的修补措施。
[Abstract]:In recent years, with the rapid development of transportation, the level of bridge construction in China has reached a new level. The prestressed concrete box girder bridge is competitive because of the advantages of flexural section, large torsional stiffness, convenient construction and low cost. In recent years, the bridge type has made a great breakthrough in both scale and span. However, there are more and more problems, of which cracking is common in both existing and ongoing construction projects. The cracking problem in construction will affect the quality and safety of the subsequent construction, make the structure have defects and bury hidden dangers, but the cracks in the completed bridge will not only affect the beauty of the structure. At the same time, the safety and durability of the structure pose a great threat, so it is necessary to study the cracking of concrete box girder systematically and deeply, to explore the root cause of the disease. In this paper, based on the background of Jiangkou Jialing River Bridge in Guangyuan City and the actual situation on the spot, the factors affecting the cracks of prestressed concrete box girder bridge are studied. The specific work contents are summarized as follows: 1. Through consulting a large number of books and related documents on cracking of prestressed concrete box girder bridges, we have a certain understanding of this kind of problems, and through summing up and analyzing, we get the causes of the cracks. Distribution characteristics and Mechanical characteristics, in order to guide the follow-up work, the influence of vertical temperature gradient on the stress of bridges is obtained through finite element analysis and combining with the current code of our country. The relationship between the most unfavorable temperature gradient effect and the live load effect is compared and analyzed, which shows that the temperature gradient has a great influence on the bridge force, and two other foreign codes are selected at the same time. After calculation and analysis, it is found that the temperature gradient effect under the three specifications is quite different. Therefore, in the case of special climatic environment or engineering background, a more accurate temperature effect of .3 can be obtained by calculating and analyzing the temperature observation in the field. The influence law of the longitudinal prestressing loss on the longitudinal stress of the whole bridge is obtained, and the most unfavorable section is obtained, which provides a useful reference for the future engineering design. 4. The actual distribution of box girder cracks is simulated by using ANSYS large and universal finite element analysis. Through calculation and analysis, it is found that under the condition of normal working of longitudinal prestressed tendons, excessive loss of vertical prestress and unreasonable design of web size are the main causes of cracks in box girder webs. Based on the analysis of the influencing factors, the paper puts forward the crack control measures of box girder from the aspects of the improvement of longitudinal and vertical prestress, reasonable reinforcement, box girder size, temperature effect and construction technology, and puts forward corresponding repair measures for different cracks.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.57

【参考文献】