开裂RC桥梁动态可靠度分析及研究
发布时间：2018-09-08 17:46
【摘要】：近几年来,我国交通事业快速发展,国家高速公路网逐渐完善,RC桥梁的建设所占比重也越来越大。但随着RC桥梁服役时间的增长,人们在RC桥梁上发现了许多不同类型的裂缝,RC桥梁的开裂大大降低了桥梁的承载能力及耐久性;同时由于近几年桥梁事故时有发生,桥梁开裂被认为是桥梁破坏前兆,人们对其产生强烈的恐惧感。对开裂RC桥梁的动态可靠度进行研究及对其剩余寿命进行预测,为开裂RC桥梁的维修加固提供理论依据,具有重要的理论价值和现实意义。本文依托福建省交通厅重点科技发展项目——“福建混凝土桥梁防裂对策及预防性建养关键技术研究”,以某一开裂简支T梁桥为研究对象,对开裂RC桥的荷载效应、抗力衰减模型进行了研究,并基于验算点法(JR法)计算RC桥梁动态可靠度,然后根据动态可靠度的计算结果对该桥的剩余寿命进行了讨论。主要工作内容如下:1、根据由福建省交通厅组织的对在役混凝土桥梁开裂情况的调查结果,分析了各类混凝土桥梁裂缝的分布规律:(1)钢筋混凝土T梁桥的开裂情况主要是支座、1/4及1/5跨径附近翼缘板斜向开裂和翼缘板与腹板交接处的纵向开裂两种;(2)RC小箱梁桥主要是在在1/5L~1/3L处的底板纵向开裂及横向开裂、箱梁间湿接缝处的横向开裂、梁间现浇段段处的竖向开裂三种开裂形式。2、根据可靠度的基本原理,介绍动态可靠度的基本概念。并针对工程实例,基于动态可靠度理论的混凝土碳化深度及钢筋锈蚀随时间变化的动态模型,建立了考虑开裂影响的RC简支T梁桥荷载效应及抗力衰减随时间变化的动态模型,讨论了结构可靠度随时间变化的规律。3、利用MATLAB 2014a数学计算软件编写验算点法(JC法)计算动态可靠指标程序,并对某一开裂简支T梁桥动态可靠度进行求解,根据计算出的动态可靠指标,对其剩余寿命进行了预测与分析,重点分析了超载运行及裂缝进一步扩展时对桥梁结构动态可靠度及剩余寿命的影响。相同时间内,超载运营比正常荷载运营时的可靠度要小,且超载运营时的可靠度下降速率要快,并使RC桥梁结构的使用寿命大大缩减;在相同服役时间段内及相同运营状态下,桥梁开裂程度越严重,RC桥梁结构的可靠度越小,则表面RC桥梁的正常使用寿命就越短,这样将严重影响桥梁建设及交通网线规划。4、处理好裂缝问题的关键所在就是正确认识混凝土结构的裂缝。只有能够正确判断裂缝产生的各种原因以及影响程度,才有可能对裂缝的性质及其对结构安全及使用功能的影响做出科学的判断,才能采取针对性的措施进行更有把握地、更有效地处理。本文最后根据前面对开裂RC桥梁动态可靠度的分析研究,提出了一些预防混凝土桥梁开裂的措施及开裂后的修复方法。
[Abstract]:In recent years, with the rapid development of transportation in China, the construction of RC bridges in the national highway network is becoming more and more important. However, with the increase of service time of RC bridge, many kinds of cracks and cracks of RC bridge have been found in RC bridge, which greatly reduce the bearing capacity and durability of the bridge, at the same time, because of bridge accidents in recent years, Bridge cracking is regarded as a precursor of bridge damage, and people have a strong fear of it. This paper studies the dynamic reliability of cracked RC bridge and predicts its residual life, which provides the theoretical basis for the maintenance and reinforcement of cracked RC bridge, and has important theoretical value and practical significance. In this paper, based on the key scientific and technological development project of Fujian Provincial Communications Department, "study on crack Prevention Countermeasures and key techniques of Preventive Construction and maintenance of concrete Bridges in Fujian Province", a cracked simply supported T-beam bridge is taken as the research object, and the load effect of cracked RC bridge is studied. The resistance attenuation model is studied and the dynamic reliability of RC bridge is calculated based on JR method. Then the residual life of the bridge is discussed according to the calculation results of dynamic reliability. The main contents of the work are as follows: 1. According to the results of an investigation on the cracking of existing concrete bridges organized by the Fujian Provincial Communications Department, The distribution of cracks in various concrete bridges is analyzed as follows: (1) the cracking of reinforced concrete T-beam bridges is mainly divided into two types: (1) the slanting cracking of flange slabs near the support 1 / 4 and 1 / 5 span and the longitudinal cracking at the junction of flange slabs and web plates; (2) the RC box. Girder bridge is mainly at the bottom of the 1/5L~1/3L longitudinal cracking and transverse cracking, According to the basic principle of reliability, the basic concept of dynamic reliability is introduced. Based on the dynamic reliability theory, the dynamic model of concrete carbonation depth and steel corrosion changing with time is established, and the dynamic model of load effect and resistance attenuation of RC simply supported T-beam bridge with the influence of cracking is established. This paper discusses the rule of structural reliability varying with time .3.Using MATLAB 2014a mathematical calculation software, the program of calculating dynamic reliability index by checking point method (JC method) is compiled, and the dynamic reliability of a cracked simply supported T-beam bridge is solved. According to the calculated dynamic reliability index, the residual life of the bridge is predicted and analyzed, and the influence of overload operation and crack expansion on the dynamic reliability and residual life of bridge structure is analyzed. In the same period of time, the reliability of overloading operation is smaller than that of normal load operation, and the reliability decline rate of overload operation is faster, and the service life of RC bridge structure is greatly reduced; in the same period of service and under the same operating condition, The more serious the cracking degree of the bridge is, the less reliable the RC bridge structure is, the shorter the normal service life of the surface RC bridge is. This will seriously affect the bridge construction and traffic network planning. 4. The key to deal with the crack problem is to correctly understand the cracks of concrete structure. Only if we can correctly judge the causes and the degree of influence of cracks, can we make a scientific judgment on the nature of cracks and their influence on structural safety and use function, and then we can take targeted measures to carry out more sure measures. Deal with it more effectively. Finally, according to the analysis and study of the dynamic reliability of cracked RC bridges, some measures to prevent the cracking of concrete bridges and the repair methods after cracking are put forward in this paper.
【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】：U441
本文编号：2231238
[Abstract]:In recent years, with the rapid development of transportation in China, the construction of RC bridges in the national highway network is becoming more and more important. However, with the increase of service time of RC bridge, many kinds of cracks and cracks of RC bridge have been found in RC bridge, which greatly reduce the bearing capacity and durability of the bridge, at the same time, because of bridge accidents in recent years, Bridge cracking is regarded as a precursor of bridge damage, and people have a strong fear of it. This paper studies the dynamic reliability of cracked RC bridge and predicts its residual life, which provides the theoretical basis for the maintenance and reinforcement of cracked RC bridge, and has important theoretical value and practical significance. In this paper, based on the key scientific and technological development project of Fujian Provincial Communications Department, "study on crack Prevention Countermeasures and key techniques of Preventive Construction and maintenance of concrete Bridges in Fujian Province", a cracked simply supported T-beam bridge is taken as the research object, and the load effect of cracked RC bridge is studied. The resistance attenuation model is studied and the dynamic reliability of RC bridge is calculated based on JR method. Then the residual life of the bridge is discussed according to the calculation results of dynamic reliability. The main contents of the work are as follows: 1. According to the results of an investigation on the cracking of existing concrete bridges organized by the Fujian Provincial Communications Department, The distribution of cracks in various concrete bridges is analyzed as follows: (1) the cracking of reinforced concrete T-beam bridges is mainly divided into two types: (1) the slanting cracking of flange slabs near the support 1 / 4 and 1 / 5 span and the longitudinal cracking at the junction of flange slabs and web plates; (2) the RC box. Girder bridge is mainly at the bottom of the 1/5L~1/3L longitudinal cracking and transverse cracking, According to the basic principle of reliability, the basic concept of dynamic reliability is introduced. Based on the dynamic reliability theory, the dynamic model of concrete carbonation depth and steel corrosion changing with time is established, and the dynamic model of load effect and resistance attenuation of RC simply supported T-beam bridge with the influence of cracking is established. This paper discusses the rule of structural reliability varying with time .3.Using MATLAB 2014a mathematical calculation software, the program of calculating dynamic reliability index by checking point method (JC method) is compiled, and the dynamic reliability of a cracked simply supported T-beam bridge is solved. According to the calculated dynamic reliability index, the residual life of the bridge is predicted and analyzed, and the influence of overload operation and crack expansion on the dynamic reliability and residual life of bridge structure is analyzed. In the same period of time, the reliability of overloading operation is smaller than that of normal load operation, and the reliability decline rate of overload operation is faster, and the service life of RC bridge structure is greatly reduced; in the same period of service and under the same operating condition, The more serious the cracking degree of the bridge is, the less reliable the RC bridge structure is, the shorter the normal service life of the surface RC bridge is. This will seriously affect the bridge construction and traffic network planning. 4. The key to deal with the crack problem is to correctly understand the cracks of concrete structure. Only if we can correctly judge the causes and the degree of influence of cracks, can we make a scientific judgment on the nature of cracks and their influence on structural safety and use function, and then we can take targeted measures to carry out more sure measures. Deal with it more effectively. Finally, according to the analysis and study of the dynamic reliability of cracked RC bridges, some measures to prevent the cracking of concrete bridges and the repair methods after cracking are put forward in this paper.
【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】：U441
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