Development of an Expert System for Servicesbility Rating of Concrete Bridges

指出了开发计算机辅助桥梁等级系统对既有桥梁的维护、诊断、维修和修复的必要性。在役既有桥梁存在多种损伤因素，存在多种损伤过程。桥梁等级评定的主体部分是桥梁养护体系的核心，是在相关领域专家主观判断的基础上构建的。考虑到日益增长的桥梁维修领域缺乏专家，为了准确诊断桥梁状况，包括桥梁工程师专业经验、桥梁等级知识等主观信息在内的桥梁等级的系统化已成为一个重要问题。本文开发了一个混凝土桥梁使用性能评定专家系统（桥梁评定专家系统），该系统由包括评定主观信息在内的知识库、推理引擎、数据参考模块、计算模块、说明模块、知识获取模块和I/O模块等几个部分组成。专家系统使用的计算机系统和主要语言是日本NEC公司的PC-9801VX41个人计算机，分别使用PROLOG和C语言。对于包含与评级相关的主观信息的知识库的构建，主观信息不能被分配为真或假等二进制代码，在处理这些信息时是一个不可避免的问题。为了解决这一问题，在本系统中引入了基于Dempster & Shafer理论的基本概率概念。在Dempster & Shafer的理论中，将经验和知识引入知识库的上概率是通过向桥牌专家发放问卷来获得的。该系统产生的最后阶段的评级结果被认为是由“安全”、“略安全”、“中等”、“略危险”、“危险”等语言表达的五个要素来表示的，模糊值是主观不确定性的程度。通过对几座混凝土桥梁现场数据的分析，验证了该专家系统的适用性。通过对钢筋混凝土桥梁老化梁板的应用，利用专家系统进行推理，得到了合理的结果。少

The necessity of developing a computer-aided bridge rating system gas been pointed out for maintenance, diagnosis, repair and rehabilitation of existing bridges. There are multiple processes of damage with a number of damage factors in existing bridges in service. The major part of bridge rating which is the kernal of bridge maintenance system has been constructed based on the subjective judgment of experts in the related fields. By considering that there is a lack of experts in the increasing filed of bridge maintenance and for the exact diagnosis of bridge conditions, the systematization of bridge rating including the subjective information of bridge engineers such as professional experience, knowledge on bridge rating, etc. has become an important problem.In this paper, an expert system for serviceability rating of concrete bridges (Bridge Rating Expert System) is developed based on a combination of several components which are the knowledge base including the subjective information … More related to the rating, the inference engint, the data reference module, the calculation module, the explanation module, the knowledge acquisition module and the I/O module. The computer system and main language which is used in the expert system are the PC-9801VX41 personal computer made by NEC corporation, Japan and PROLOG and C languages, respectively.For the construction of the knowledge base including the subjective information related to the rating, it is an unavoidable problem in dealing with subjective informations which cannot be allotted binary codes such as true or false. As a remedy to this problem, a concept of the basic probability according to the Dempster ＆ Shafer s theory is introduced in the present system. The upper probabilities in the Dempster ＆ Shafer's theory to introduce experiences and knowledge accumulated into the knowledge base are obtained through questionnaires sent out to bridge experts.The results of the rating at the final stage produced by this system are considered to be represented by five elements expressed by the linguistic expressions "safe" "slightly safe" "moderate" "slightly danger" "danger" with the fuzziness value which is the degree of subjective uncertainty.A few concrete bridges on which field data have been collected are analyzed to demonstrate the applicability of this expert system. Through the application to the deteriorated reiforced concrete bridge girders and slabs, reasonable results are obtained by inference with the expert system. Less