基于证据理论的混凝土桥梁耐久性状况评定方法

A Method for Assessing Durability of Concrete Bridges Based on Evidence Theory

耐久性病害是混凝土桥梁最常见的一类病害,发展到一定程度将威胁结构安全,准确评定桥梁结构耐久性状况关系到桥梁养护的科学决策。针对目前耐久性状况评定方法多从环境角度区分,缺少从结构技术状况角度综合评定,提出了基于证据理论的耐久性状况综合评定方法。研究了混凝土桥梁耐久性病害劣化的5个阶段,并与桥梁技术状况的5类划分相对应,细化了每类状况的养护对策,使综合评定结果与现有桥梁养护管理体系相协调。针对综合评定时影响因素多、不确定信息多、层次划分多的问题,引入基于证据理论的合成算法和推理算法,通过逐层合成,降低了评定误差,科学地处理了不确定信息。评定方法以检测评定结果的5类等级划分为导向,将检测参数的评定标度结果作为底层函数,考虑各参数的相应权重,运用证据推理算法进行合成,即可得到某一构件的耐久性评定等级。根据构件、部件的权重依次合成,可得到其上一层级的评定结果。每一层评定结果均能给出隶属于相应等级的概率,对于未检测的参数或构件作为不确定信息处理,可以给出不隶属于任何一个等级的概率,如此可更好地得到宏观评定结果。基于证据理论的耐久性状况评定方法可以将更多检测参数引入到评定过程中,使得评定结果更全面、更精细,更科学。

Durability disease is the most common disease of concrete bridges,which will threaten the structural safety when it develops to a certain extent.Accurate assessment of the durability of bridge structures is related to the scientific decision-making of bridge maintenance.In view of the fact that the current durability assessment methods are mostly differentiated from the environmental perspective and lack of comprehensive assessment from the perspective of structural technology,a durability comprehensive assessment method based on evidence theory is proposed.The 5 stages of durability disease deterioration of concrete bridges corresponding to the 5 categories of bridge technical conditions are studied,and the maintenance countermeasure for each category are refined,so that the comprehensive assessment result is coordinated with the existing bridge maintenance management system.In view of the problems of multiple influencing factors,uncertain information and hierarchical division in comprehensive assessment,the synthesis algorithm and reasoning algorithm based on evidence theory are introduced.Through layer by layer synthesis,the assessment error is reduced and the uncertain information is processed scientifically.The assessment method is guided by the classification of 5 types of detection and evaluation results,taking the assessment scale result of test parameters as the underlying function,considering the corresponding weight of each parameter,the synthesis is performed by using the evidential reasoning algorithm,and the durability assessment grade of a component can be obtained.The synthesis is performed according to the corresponding weight of each component or each part,the assessment result of the upper level can be obtained.The assessment result of each level can give the probability belonging to the corresponding grade.The untested parameters or components can be treated as uncertain information,and the probability that does not belong to any grade can be given,in this way,the macro assessment result can be better obtained.The durability assessment method based on evidence theory can introduce more detection parameters into the assessment process,making the assessment result more comprehensive,more precise and more scientific.