Knowledge-Based Fuzzy Expert System to the Condition Assessment of Historic Road Bridges

A systematic methodology for condition assessment of the historic road bridges was needed because of the poor and inadequate condition of bridges which cannot satisfy everyday-day dynamic loads and deteriorations due to the aging process. Thus in this study, a new expert system based on the knowledge approach has been proposed to develop a systematic procedure for condition assessment of these bridges using fuzzy logic and sets of α-cuts. Each bridge is divided into three components: superstructure, substructure, and equipment, and each component is divided into relevant elements. These elements are evaluated by an expert and their ratings are fuzzified according to defined fuzzy sets, their membership functions, and linguistic values. Furthermore, fuzzy structural importance is given to ratings of each element. Combinations of these two values are calculated to obtain a fuzzy rating of the component using the Fuzzy Weighted Geometric Mean (FWGM). Finally, for the defuzzification of the component rating, the centroid method is proposed. The Analytic Hierarchy Process (AHP) is used for comparison of the components. The bridge condition rating is achieved by summering all the components ratings multiplied by their relative importance, and it is presented as a value of the Historic Road Bridge Condition Assessment Index (HRBCAI). The validation is conducted on the bridges built until the end of the Austro-Hungarian Monarchy in Split-Dalmatia County, Croatia.

PENILAIAN KONDISI JEMBATAN MENGGUNAKAN BRIDGE MANAGEMENT SYSTEM (BMS) DAN BRIDGE CONDITION RATING (BCR)

The bridge assesment and checking is an effort to gain well performance and vouch the decline condition of the bridge to ensure the bridges could be restored back under it stability basedits performance. Nowadays, the bridge inspections were carried out independently by the Perencanaan dan Pengawasan Jalan Nasional (P2JN) by using the Bridge Management control System (BMS). Referring to the latest bridge indicators, the bridge checks are carried out by tender system and consultants. The aim of this study is to check the bridge damage by isnpecting the condition value and damage code in the field by using BMS and Bridge Condition Rating (BCR) in order to obtain the accuracy in bridge maintenance. This research was conducted on 4 Bridges on the road Kr. Raya-BTS. Banda Aceh and Lambaro-BTS. Pidie, those are Kr. Angan bridge (STA. 013 + 400), Kr. Inong bridge (STA. 040 + 600), Kr. Geunapet A bridge (STA. 063 + 700), and Kr. Geunapet B bridge (STA. 063 + 700). Based on the BMS method, the writer found that Kr. Angan bridge was in 0 condition value, the condition value for Kr. Inong bridge was 2, the condition value for Kr. Geunapet A bridge was 0 and Kr. Geunapet B bridge was 0. Based on the results by using BCR method, it can be seen that the condition value for Kr. Angan bridge was 5.36, 5,52 for Kr. Inong bridge, 5,28 for the Kr. Geunapet A and 5,28 for Kr. Geunapet B. In the method of BMS the assessment of the condition of the bridge from good to bad starts from a small to large values namely from 0 to 5, while in the method of crack the assessment of conditions starting from bad to good is 7 to 1. Furthermore, referring to the BMS and BCR comparison, it could be concluded that both BMS and BCR needed the same proposed treatment in form of regular and periodic maintenance. For some components of the bridge handling is needed in the form of repairs such as repairing cracks in the concrete, as well as repairs to the expansion joint. While in the BCR method there was no assessment to handle floor drainage systems, backrests and safety building.

Sustav za podršku odlučivanju u planiranju obnove povijesnih cestovnih mostova

In this dissertation a study of a decision support system (DSS) establishment in the rehabilitation planning of historic road bridges is given. The theoretical background of DSS, historic road bridges explanation, their characteristics and importance and potential rehabilitation methods are presented at a beginning of dissertation. Furthermore, the newly formed DSS has been designed and described as well as its basic elements: database, knowledge base, model base and dialogue. The research focus was in designing the model base, within which four new models are developed. The structure of the database has been presented and adequate data are collected as well as required knowledge to form a knowledge base. The collected data and knowledge influenced the modeling process in the model base. Through three levels of decision-making, an interaction between the mentioned basic elements of the DSS was established and its functionality was introduced. At the operational level, data were collected for databases such as: name and location of bridges, bridge characteristics, rehabilitation methods, spatial-functional and financial constraints and expert visual bridge condition estimation. At the tactical level, the way of forming goal three and relevant criteria for an individual bridge rehabilitation method selection are defined. A new model has been developed to assist in making tactical decisions in the selection of rehabilitation methods, based on defined criteria and a multicriterial approach using the AHP and PROMETHEE methods. After design of the model on tactical level, the model for rehabilitation priority ranking of all historical bridges on strategic level is developed. Thus, the methodology for criteria establishing, necessary for the realization of the newly developed model, is presented. These are the strategic criteria and as a result of the multicriteria methods (AHP, PROMETHEE and GAIA) application, the overall ranking of the analyzed bridges was obtained. Among the above mentioned criteria, is the criterion that presents historic road bridge condition evalutaion. Therefore, a new indicator called the Index of Historical Road Bridge Condition Rating (IHRBCR) was developed. The value of IHRBCR is the result of a newly established model of historic road bridges condition estimating. This model is based on combining a defined way of implementing expert visual bridge condition rating, modified fuzzy logic and multicriteria method (AHP). The overall rank of bridges, obtained as a result of the model for rehabilitation priority ranking of historic road bridges, with the definition of the necessary spatial-functional and financial constraints and their combination, was used for the realization of the newly developed model for manager's approach selection. As a result of the analyzed model, using the multicriteria method PROMETHEE V, a set of bridges for rehabilitation was obtained on an annual basis. The main goal of the dissertation is to develop a DSS that will assist the final decision-maker to carry out the rehabilitation planning of historic road bridges in the systematic and organized manner. The model was validated on the case of historic road bridges in the area of Split-Dalmatia County, built during or before the Austro-Hungarian Monarchy.