基于概率理论的桥梁承载能力评定方法研究

发布时间：2018-03-18 10:44

本文选题：安全性评估　切入点：承载力　出处：《沈阳建筑大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着桥梁服役时间的增长,由于环境腐蚀及交通量的不断增加,逐渐产生结构功能衰退的现象,其可靠度将降低。对既有桥梁结构进行承载力鉴定及可靠度评估是保证结构在未来服役期内安全使用的前提。由于结构的抗力随着时间而变异,将结构的抗力视为随机变量。另外,结构荷载效应也是因服役评估期不同而随时间变化。另一方面如果桥梁经历了某次荷载的验证作用,其数据结果能用于结构的参数修正,从而使结构的可靠度评估更加符合实际。针对这些情况,本文主要做了如下工作：(1)总结了结构可靠度的基本概念、原理及计算可靠性指标的常用方法。(2)基于恒载模型、车辆荷载模型,在国内外各种调查资料的基础上,研究了混凝土桥梁的荷载效应模型。(3)根据可靠性指标的计算方法,采用JC法对西苏堡特大桥上部结构的可靠度进行了计算分析。各主要截面可靠度指标均大于目标可靠度4.7,确定该工桥安全性高,即符合国家现行标准规范要求的。(4)根据时变可靠度理论预测了西苏堡特大桥在后续服役期的可靠度指标。达到了使用年限的要求,并且预留了一定的安全度,数据表明桥梁的可靠度随着结构服役时间的增长在不断降低。(5)介绍了验证荷载基本原理,通过桥梁荷载试验提供的数据资料对结构抗力直接进行推断,进而对结构的安全性做出合理评价的方法。在验证荷载和抗力衰减两个因素中,抗力衰减对结构可靠度的影响更显著；证明考虑抗力变化后结构可靠性有所降低,环境条件越恶劣,结构可靠性降低程度越大,并有可能不满足目标可靠度要求。(6)通过实例计算和理论分析,指出验证荷载能够更好的分析出结构实际的可靠度,主要是因为影响了抗力的尾部的有效截去,验证荷载法作为一种对结构抗力进行直接性推断的方法,具有理论上的优越性。研究结果表明：采用时变可靠度理论对既有桥梁结构的安全性评定,不仅可以使工程师对结构目前的状况有较好的了解,还可以使相关管理部门对结构未来的服役情况和近似预测,并且根据时变可靠度评定的结果开发桥梁的健康监测系统。我们还需根据结构的不同实际服役环境来选择合适的抗力衰减规律,对结构后继服役期内的可靠度进行正确评估,进而利用可靠指标的变化规律为结构制定合理的维修加固方案。另一方面,在考虑验证荷载下的可靠度分析中,由于结构可靠度分析的验证荷载法建立在非破坏性的验证荷载试验基础上,并可使结构可靠度在一定条件下得到提高,因此该法有着较好的应用前景。面对实际还存在诸如试验方法、试验结果评价等问题,还需进一步研究和实践。
[Abstract]:With the increase of the service time of the bridge, because of the environment corrosion and the increasing traffic volume, the structure and function decline gradually. Its reliability will be reduced. The evaluation of bearing capacity and reliability of existing bridge structures is the prerequisite to ensure the safe use of the structures during the future service period. Because the resistance of the structures varies with time, The resistance of the structure is regarded as a random variable. In addition, the structural load effect changes with time due to the different service evaluation period. On the other hand, if the bridge has undergone a certain load verification, the results of the data can be used to modify the structure parameters. In order to make the reliability evaluation of the structure more practical, the main work of this paper is as follows: 1) summarize the basic concept of structural reliability, principle and common method of calculating reliability index based on dead load model. Based on the investigation data at home and abroad, the load effect model of concrete bridge is studied. The reliability of the superstructure of Xisubu super bridge is calculated and analyzed by using JC method. The reliability index of each main section is greater than the target reliability of 4.7. It is determined that the safety of the bridge is high. According to the theory of time-varying reliability, the reliability index of the Xisubao super bridge in the subsequent service period is predicted, which meets the requirements of service life and reserves a certain degree of safety. The data show that the reliability of the bridge decreases with the increase of the service time of the structure. (5) the basic principle of the verification load is introduced, and the resistance of the structure is inferred directly from the data provided by the bridge load test. In the two factors of verifying the load and the resistance attenuation, the influence of the resistance attenuation on the structural reliability is more significant, and it is proved that the reliability of the structure decreases after considering the change of the resistance. The worse the environmental conditions, the greater the degree of structural reliability reduction, and it is possible to not meet the target reliability requirements. (6) through the example calculation and theoretical analysis, it is pointed out that the verification load can better analyze the actual reliability of the structure. The main reason is that the effective truncation of the tail of the resistance is affected, and the load method is verified as a direct method to infer the resistance of the structure. The research results show that using the time-varying reliability theory to evaluate the safety of existing bridge structures can not only make engineers have a better understanding of the current situation of the structures, It can also enable the relevant management to predict the future service situation of the structure and approximate forecast. According to the results of time-varying reliability evaluation, the bridge health monitoring system is developed. According to the different actual service environment of the structure, we should select the appropriate law of resistance attenuation, and evaluate the reliability of the bridge during the subsequent service period correctly. On the other hand, in the reliability analysis under the consideration of the verification load, the reliability analysis is used to make a reasonable maintenance and reinforcement scheme for the structure. Because the validation load method for structural reliability analysis is based on the non-destructive verification load test, the reliability of the structure can be improved under certain conditions. Therefore, this method has a good prospect of application, and it needs further study and practice in the face of problems such as test methods and evaluation of test results.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U446

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