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It is becoming an important social problem to make maintenance and rehabilitation of existing infrastructures such as bridges, buildings, etc. in the world. The kernel of such structure management is to develop a method of safety assessment on items which include remaining life and load carrying capacity. The purpose of this paper is to summarize the finding of up-to-date research articles concerning the application of knowledge-based systems to assessment and management of structures and to illustrate the potential of such systems in the structural engineering. In here, knowledge-based systems include knowledge-based expert systems incorporation with artificial neural networks, fuzzy reasoning and genetic or immune algorithms. Specifically, two modern bridge management systems (BMS’s) are presented in the paper. The first is a BMS to assess the performance and derive optimal strategies for inspection and maintenance of concrete bridge structures using reliability based and knowledge-based systems. The second is the concrete bridge rating expert system (J-BMS BREX) to evaluate the performance of existing bridges by incorporating with artificial neural networks and fuzzy reasoning.

The State Representation Methodology (SRM) combined with the Frequency Slice Wavelet Transform (FSWT), which is a new time–frequency analysis tool, is proposed for assessing the condition of bridges on the basis of bridge monitoring data. First, this paper presents an overall description of the SRM method via FSWT analysis. It then shows, through numerical simulations, some novel characteristics and advantages of FSWT analysis in contrast to the conventional wavelet approach and the feature extraction accuracy of SRM analysis for the detection of bridge damage on the basis of monitoring data. The principal results obtained through this study can be summarized as follows: (1) details of a newly proposed SRM and its application to bridge condition assessment based on bridge monitoring data are introduced. The proposed SRM combined with the FSWT is validated as a novel time–frequency analysis tool for assessing bridge condition on the basis of bridge monitoring data. (2) New properties of FSWT analysis are demonstrated, and advantages in contrast to the traditional wavelet method are highlighted. Feature extraction in SRM analysis is precise for damage detection in a bridge system on the basis of monitoring data and using numerical simulations.

It is becoming an important social problem to make maintenance and rehabilitation of existing short and medium span(10-20 m) bridges because there are a huge amount of short and medium span bridges in service in the world. The kernel of such bridge management is to develop a method of safety(condition) assessment on items which include remaining life and load carrying capacity. Bridge health monitoring using information technology and sensors is capable of providing more accurate knowledge of bridge performance than traditional strategies. The aim of this paper is to introduce a state-of-the-art on not only a rational bridge health monitoring system incorporating with the information and communication technologies for lifetime management of existing short and medium span bridges but also a continuous data collecting system designed for bridge health monitoring of mainly short and medium span bridges. In this paper, although there are some useful monitoring methods for short and medium span bridges based on the qualitative or quantitative information, mainly two advanced structural health monitoring systems are described to review and analyse the potential of utilizing the long term health monitoring in safety assessment and management issues for short and medium span bridge. The first is a special designed mobile in-situ loading device(vehicle) for short and medium span road bridges to assess the structural safety(performance) and derive optimal strategies for maintenance using reliability based method. The second is a long term health monitoring method by using the public buses as part of a public transit system (called bus monitoring system) to be applied mainly to short and medium span bridges, along with safety indices, namely, “characteristic deflection” which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface, and a structural anomaly parameter.

This paper introduces the details of a transient damping feature extracting method based on the bridge monitoring data with the aid of the frequency slice wavelet transform (FSWT) which is a time-frequency space analysis tool and its application to damage detection of the bridges. The proposed method via the state representation methodology (SRM) algorithm has been verified by the state probably density distribution using the vibration signal from a laboratory bridge monitoring system. As a result, the system state vector as a non-parametric state variable will be able to apply to assess the state change (damage) of the bridge structures by expression of the state probably density distribution.

The two principal authors have been developing a Bridge Management System, viz. the J-BMS for individual bridges. The system when integrated with the Concrete Bridge Rating Expert System (BREX) can be used to evaluate the serviceability of existing concrete bridges. The integrated system is able to predict the deterioration process of the existing bridge superstructure components as well as assess a broad array of optional corrective strategies. The system has the capability to search and retrieve from a data bank, the necessary information, carry out suitable analyses to arrive at some recommendations that would help users to optimize their decisions based on engineering aspects, cost and economic issues and bridge management policies. A characteristic feature of the present system is the use of the Genetic Algorithm (GA) technique to search for an approximate optimal maintenance plan. The present study is part of an attempt to develop a comprehensive decision support system for maintenance strategies based on life cycle cost analysis of an entire bridge inventory, which form part of a highway network. Since formulation of an optimum bridge maintenance program for an entire stock of bridge structures is usually impeded by a lack of sufficient information on their existing conditions, the capability of the system was tried out, with a view to enhancing its capability, by applying it to a limited number of individual existing bridges, categorised as belonging to a typical bridge inventory. The results obtained are compared to those provided by experienced maintenance engineers by way of specially designed survey forms.

This paper describes an acquisitive method of rule‐type knowledge from the field inspection data on highway bridges. The proposed method is enhanced by introducing an improvement to a traditional data mining technique, i.e. applying the rough set theory to the traditional decision table reduction method. The new rough set theory approach helps in cases of exceptional and contradictory data, which in the traditional decision table reduction method are simply removed from analyses. Instead of automatically removing all apparently contradictory data cases, the proposed method determines whether the data really is contradictory and therefore must be removed or not. The method has been tested with real data on bridge members including girders and filled joints in bridges owned and managed by a highway corporation in Japan. There are, however, numerous inconsistent data in field data. A new method is therefore proposed to solve the problem of data loss. The new method reveals some generally unrecognized decision rules in addition to generally accepted knowledge. Finally, a computer program is developed to perform calculation routines, and some field inspection data on highway bridges is used to show the applicability of the proposed method.

This paper describes a method of the remaining life prediction of an aged RC-T girder bridge based on the concrete core test results. The remaining life prediction of the bridge can also be quantitatively estimated by applying the J-BMS with the field inspection data. It needs to be verified through the concrete core specimen tests extracted from some parts on main girders, deck slabs, and bridge piers, such as compressive strength, carbonation depth, chloride ion concentration, and so on. This study is focused on the performance and validation of the deterioration assessment used on concrete cores, which was collected from the target bridge. In this study, data obtained from collected concrete core specimens were examined by chloride ion and carbonation tests. As a result, carbonation is more dominant than the chloride ion on the deterioration process although the bridge is located within 1 km upstream from the mouth of the river pouring into the Seto Inland Sea. The carbonation rate coefficient and the apparent diffusion coefficient of chloride ions were determined, and the remaining life prediction where the main factor of deterioration is carbonation has been found from the concrete core test results. On the estimated cumulative amount steel corrosion (Q) of 75 mg/cm2, the remaining life of the bridge is predicted to be approximately 7 years. Also, the localized concrete core test results can be used for an entire span evaluation by visualized distribution results using an approximating function.

This paper describes health examination and remaining service life prediction procedures for an aged reinforced concrete (RC) T-girder bridge via visual inspection data. The Bridge Management System (J-BMS) that was previously developed by the authors, and which is capable of forecasting the deterioration process of existing bridge members, was applied to evaluate the safety indices (health score) and remaining service life of the subject bridge based on these test results. Using these procedures, the remaining service life of an aged RC-T girder bridge can quantitatively be estimated by applying the bridge rating expert (BREX) system, which is a subsystem of the J-BMS that incorporates field inspection data. In this study, visual inspection was carried out on an aged bridge by professional visual inspectors, during which all variations of the inspection results were evaluated using a five-step questionnaire. Additionally, it was found that health score (safety indices) and remaining service life predictions were influenced by the learning (supervised) data selection.

This paper introduces a newly proposed “state representation methodology (SRM)” and its application to bridge condition assessment based on the bridge monitoring data. The SRM is a novel tool that can provide some ideas and algorithms for data mining in the bridge monitoring system. The state of a system such as bridge structure can be obtained by a state variable calculated from a state representation equation (SRE). A kernel function method which plays an important role in the support vector machines is applied to obtain solutions of the SRE. In the computation of the SRE, it needs to be changed into a large-scale linear constraint problem (LSLCP). A new compatible algorithm is therefore proposed for solving technique of the LSLCP. Before using the SRM, it is necessary that the system features need to extract from the complex responses observed data in the system. Consequently, a new time–frequency analysis tool, called frequency slice wavelet transform (FSWT), will be able to powerfully reveal a change of the characteristics in vibration signal. The FSWT produces five new properties in contrast with the traditional wavelet transform. Therefore, the paper will show the new method that can be used widely in signal processing. In this paper, a general theory for the nonparametric description of the infrastructure system’s state will also be introduced and will demonstrate how to apply the SRM to practical problems.

This paper describes a Remote Collaborative Visual Inspection System for integrated management by linking digital movie captured by a running vehicle and online road drawings. The newly developed road condition assessment system consists of commercially available on-board high-resolution video cameras during the visual inspection of road pavements and road appurtenances and a Web connection system. The system enables users to select a road section in a road register on an on-screen map and visually observe not only pavements but also road facilities, slopes, the state of vegetation, and road-occupying structures. The system, therefore, can be expected to help reduce visual detection failures compared with conventional visual observation from moving vehicles and make highly objective evaluation possible through observation by two or more persons. By using image data, the system also provides basic data that can be used for not only maintenance but also road planning.

Background: We sought to detect specimen mix-up by developing a new cumulative delta-check method applicable to a mixture of test items with heterogeneous units and distribution patterns. Methods: The distributions of all test results were successfully made Gaussian using power transformation. Values were then standardized into z-score (zx) based on reference interval (RI) so that limits of RI take zx=±1.96. To find a weight for summing absolute value of delta between current and previous zx (Dz), we evaluated the distribution of Dz. Its central portion was always regarded as Gaussian despite the presence of symmetrical long tails. Thus, an adjusted SD (aSD) representing the center was estimated with an iterative method. By setting 1/aSD2 as a weight factor, we computed a weighted mean of Dz as an index for specimen mix-up (wCDI). Results: The performance of wCDI was evaluated, using a model laboratory database consisting of 32 basic test items, by a simulation study generating artificial cases of mix-up. When wCDI was computed from three commonly ordered test sets consisting of 6–9 items each, its diagnostic efficiency in detecting the artificial cases was 0.937–0.967 expressed as area under ROC curves (AUC). When the performance of wCDI was evaluated simply by the number of test items (p) included in the computation, AUC gradually increased from 0.944 (p=5) to 0.976 (p=8). However, when p≥10, AUC stayed at approximately 0.98. Conclusions: wCDI was proven to be highly effective in uncovering cases of specimen mix-up. The diagnostic efficiency of wCDI depends only on the number of test items included in the computation.

This paper proposes a new method of assessing the condition of existing short- and medium-span bridges based on monitoring data obtained from public bus vibration. This paper not only describes details of a prototype monitoring system that uses information technology and sensors capable of providing more accurate knowledge of bridge performance than conventional ways but also shows a few specific examples of bridge condition assessment based on public bus vibration measured by using an in-service public bus instrumented for vibration measurement. This paper also describes a sensitivity analysis of deteriorating bridges based on city bus acceleration response conducted by the “substructure method” based on a finite element model to verify the above mentioned results regarding bridge performance. The main conclusions obtained in this study can be summarized as follows: (1) because the vibration responses of a passenger vehicle such as a city bus has a good linear relationship with the vibration responses of the target bridges, the proposed system can be used as a practical monitoring system for bridge condition assessment; (2) the results of sensitivity analysis performed by the substructure method show that public bus vibration responses are useful for the evaluation of target bridge performance; (3) the proposed method was applied to a network of real bridges in a local area to evaluate its effectiveness. The results indicate that the proposed method can be used to prioritize the repair/strengthening works of existing bridges based on various vibration information in order to help bridge administrators establish rational maintenance strategies.

The diagnosis of bridge serviceability is carried out by a combination of in-situ visual inspection, static and dynamic loading tests and analyses. Structural health monitoring (SHM) using information technology and sensors is increasingly being used for providing a better estimate of structural performance characteristics rather than above traditional methods. Because the mechanical behavior of bridges with various kinds of damage can not be made clear, it is very difficult to estimate both the damage mode and degree of damage of existing bridges. In this paper, the sensitivity of both static and dynamic behaviors of bridges are studied as a measure of damage assessment through experiments on model bridges induced with some specified artificial damages. And, a method of damage assessment of bridges based on those behaviors is discussed in detail. Finally, based on the results, a possible application for structural health monitoring systems for existing bridges is also discussed.

This paper describes the physical check method and remaining life prediction method for an aged RC (reinforced concrete)-T girder bridge and the verification of the remaining life prediction results based on either close visual inspection data or concrete core test results obtained from field tests. A bridge management system (J-BMS) was applied to evaluate the safety indices and remaining life of the bridge based on these test results. The remaining life of the bridge was quantitatively estimated by applying the J-BMS with field inspection data, and the remaining life prediction results were verified by using the strength, elastic modulus, carbonation depth, chloride ion concentration, and other results obtained from the collected concrete cores.本論文では，昭和初期に輸送の大動脈を担うために架設され，大量の交通荷重を60数年間にわたって支え続けて無事その役割を終えた，国土交通省山口河川国道事務所管轄の「KT橋(旧橋)」に対する各種現地調査に基づく撤去時健康診断と余寿命推定結果およびその検証法について具体的に述べる。すなわち，(1)４回にわたる現地調査を通じて得られた点検データを利用した「橋梁維持管理支援システム(J-BMS)」による撤去時の健康診断および余寿命推定，(2)目視点検に必然的に付随する�ばらつき�の低減手法として，バーチャルリアリティ(VR)を適用した�損傷体験支援システム�の利用効果，(3)コンクリートコアによる材料試験データに基づいた客観的な検証法を，それぞれ系統的に述べるものである。

This paper focuses on modal signal separation and damping parameter identification by a new time-frequency analysis method. With the aid of the random decrement technique (RDT), an accurate estimation method is firstly introduced both in time and frequency domains for single modal damping identification. Next, the background of a new concept of frequency slice wavelet transform (FSWT) is revealed clearly. Then, some new properties of the FSWT are briefly discussed in contrast with the wavelet transform (WT). Based on the analysis of RDT and FSWT, a frequency slice algorithm (FSA) is designed for modal separation and parameter identification. The merits of FSWT and FSA with numerical simulations and experiments are demonstrated in this paper. We finally apply the proposed methods to analyze the free-decay responses (FDR) collected from a small laboratory bridge monitoring system (LBMS). Some conclusions are drawn that the RDT being used directly in FSWT domain can bring a good damping estimator. The FSA is not limited to FDR, and also can be used to random impacting response directly. FSWT itself is a new kind of good filter, and has high performance against noise. It is significant to get damping parameter with higher accuracy through modal separation by FSWT, and FSWT can be controlled adaptively in modal separation by dynamic scale method.

本研究は道路施設の維持管理において，現況把握の重要な要素となる目視巡回に着目し，車両走行映像と路線位置，道路台帳を一元的に管理する協同点検作業環境の開発を行った．システムは車載の民生用ハイビジョンビデオカメラとWebシステムにより構成される．これにより，ユーザが地図画面から路線を選択し，道路台帳ごとのセクションにおいて舗装だけでなく，道路付帯施設，法面，植物の繁茂状況，道路占有物なども視覚的にとらえることが可能となる．そのため，通常の車上目視に比べて見落としの減少や複数人での確認による客観的な評価が可能となる．また，映像を整理しデジタルアーカイブ化することで経年変化の比較や道路計画策定時に類似する道路線形の視覚的な走行イメージの疑似体験も可能となる．

本研究では，メタ戦略の一つである従来型の粒子群最適化のアルゴリズムに対して，［1］解空間の効率的な絞り込みと，［2］粒子の移動速度に減速機能を設けるといったシンプルな改良を図ることで，これら2つの機能の相乗効果によって最適解の探索効率が向上した．また新たな試みとして，求解困難な問題と考えられていたコンクリート製下水管路の腐食劣化現象の将来予測に，この改良型粒子群最適化を適用して，腐食深度予測式を新たに構築したことを特徴とする．その際，［1］硫化水素ガスの発生量，［2］下水管内の気温の1年分の計測データ，［3］下水管路の供用年数，［4］管壁材料の種類の情報を説明変数として採用した．本論文では，この改良型粒子群最適化の有用性と，腐食深度予測手法および予測式の有効性を検証した．

本研究では，道路陥没や腐食劣化による下水管路の破損危険位置などを予測し，広域下水管網の予防保全のための計画策定に対して合理的な意思決定が一貫して行える，維持管理支援システムの構築を試みた． 筆者らが開発したシステムは，下水道台帳をはじめとする様々な管理データや下水道分野で入手可能な現場情報，過去の道路陥没履歴や調査点検記録といった蓄積情報などをデータベース化し，そして下水管内の環境情報を計測または推定することによって道路陥没が予想される箇所や微生物腐食による劣化箇所を定量的に予測して，診断箇所や診断方法の選定といった意思決定を合理的に支援することを可能にした． 本稿は，この一連の支援システムを構築したプロセスと新たに考案した様々なメタ戦略理論を概説する．

This paper introduces a new kind of time–frequency signal analysis method, called frequency slice wavelet transform (FSWT), by means of extension of short-time Fourier transform (STFT) defined directly in frequency domain. The original signal can be decomposed by frequency slice function (FSF), which is similar with the wavelet base but can be designed very freely. At the same time, the original signal can be reconstructed by a FSWT representation in an easy way without the strict limitation of wavelet theory. Some new characteristics of its time–frequency window will be shown. Due to these features, FSWT is more flexible to fit ever-changing signals, and convenient to analyze and control in application. Next, the frequency resolution ratio of signal and Dirac function, etc., are employed to study FSWT, and to select a new scale parameter. The new scale is a good balance factor between time and frequency resolution. Moreover a fast discrete algorithm of FSWT is completed. Its application is focused on transient vibration signal analysis in this paper. FSWT can not only individually represent each modal signal in frequency domain, but also correctly show its details in time domain. FSWT helps to discover some new features of the experimental signal obtained from a small laboratory bridge monitoring system. By using FSWT, the filtering under high noise, and the segmenting of signal with high damping and close modes of frequency, will be discussed. Finally, the summary shows that this paper will be able to provide a more available tool for signal analyzing simultaneously in time–frequency domain, and further to refine the wavelet theory.

アスベストによる健康被害が大きな社会問題となっている中，その飛散防止対策の徹底が喫緊の課題となっている．吹付けアスベストの処理では，表面に薬液（固化剤）を吹き付けたり，内部に薬液を浸透させる「封じ込め」と呼ばれる処理が行われることが多い．封じ込めでは，薬液が隅々まで吹き付けられ，しかも確実に浸透していることが非常に重要であるが，薬液の吹付け・注入を確認する方法は確立されていない．そこで，本研究では，コンクリート内部の探知などでも実績のある広帯域超音波を用いて，薬液が吹付けアスベストの母材（下地材）まで到達しているかを非破壊で確認する方法を提案する．さらに，現場での実験結果から，この方法の効果について述べる．

アスベストによる健康被害が大きな社会問題となっている中，その飛散防止対策が喫緊の課題となっている．特に，これからピークを迎える建築物の改修·解体に伴い発生するアスベスト含有廃棄物の適正処理の確保が極めて重要である．本研究は，アスベスト含有廃棄物の処理に関して，吹付けアスベストの除去および封じ込め工事に用いる薬液を添加，加熱することでアスベストの無害化（非繊維化，非石綿化）を試みた．アスベストは，カルシウム化合物を主成分とする薬液と混合し，700°Cの低温で加熱することで，結晶構造が崩壊して非繊維化，非石綿化が可能であることがわかった．また，現場の吹付けアスベストやアスベスト成形板に対しても，同様の効果を確認することができた．

本研究では，下水管網診断のための予防保全計画策定に対してAHP理論を援用することで，ユーザーが比較したい複数の診断候補箇所と評価基準の重要度を評定するだけで，診断方法と診断位置の順位付けが合理的かつ自動的に行える意思決定支援システムのプロトタイプを構築し，その検証を行った． 筆者らが提案する支援システムは，既存アナログデータをデータベース化し有効活用することで，代替案における一対比較の作業工程の全自動化を可能とし，一対比較行列構築やウェイト算定ならびに代替案の順位付けが整然と行えることを特徴とする．また，AHPではユーザーに大きな負担を強いる一対比較作業の問題点を大幅に改善することで，意思決定に対するユーザーの負担軽減と合理化を実現した．

アスベストによる健康被害が大きな社会問題となっている中，その飛散防止対策の徹底が喫緊の課題となっている．吹付けアスベストの処理では，アスベストを除去することが望ましいが，様々な状況のため，表面に薬液（固化剤）を吹き付けたり，内部に薬液を浸透させる「封じ込め」と呼ばれる処理が行われることが多い．封じ込めでは，薬液が隅々まで確実に吹き付けられているかどうかが非常に重要であるが，薬液の吹付け状況を簡易に確認する方法は確立されていない．そこで，本研究では，薬液に蛍光剤を混ぜ，それに紫外線（励起光）を照射することによって発光する蛍光を目視観測することにより，薬液の吹付け状況を確認する方法を提案する．さらに，現場での実験結果から，この方法の効果について述べる．

In this study, as one solution to the problem for condition assessment of existing short and medium span reinforced/prestressed concrete bridges, a new monitoring method using a public bus as part of a public transit system (bus monitoring system) is proposed, along with safety indices, namely, characteristic deflection, which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface, and a structural anomaly parameter. A basic study was conducted by using the results of technical verification experiments and numerical analysis simulation. This paper describes the details of not only how to assess the bridge condition by public bus vibration measured in operating on Ube City bus network as a specific example for verify the system but also what kind of consideration we need to apply the system to existing bridges in overseas country. publishersversion published

This paper introduces an approach to the realization of an ICT-based bridge remote monitoring system which enables real-time monitoring and control for unexpected heavy loads such as big earthquake and strong typhoon. In this paper, the integrated bridge remote monitoring system called the “Intelligent Bridge” consists of a stand-alone monitoring system (SMS) and a web-based internet monitoring system (IMS) for bridge maintenance but also its application to intelligent bridge system as an intelligent structure. For the purpose of verifying its validity to actual bridge structure, an attempt is made to study the possibility of controlling the actual structural performance by adjusting the cable forces on a 2-span continuous cable-stayed bridge model. The experimental results demonstrate that the implemented monitoring system supplies detailed and accurate information about bridge behavior for further evaluation and diagnosis, and it also opens up prospects for future application of web-based remote system to actual in-service bridges under field conditions.

In the present study a comprehensive decision support system is developed for the formation of maintenance strategies with/without annual budget limitations. This system is based on life-cycle cost analysis of an entire bridge inventory, which comprises part of a highway network. The formulation of an optimum bridge maintenance program for an entire stock of bridge structures has been impeded historically by insufficient information concerning the existing structural conditions. The capability of this optimization system was enhanced by employing Genetic Algorithms in the formation of semi-optimal solutions. This system was tested by employing to formulate a set of semi-optimal bridge management programs for a set of selected existing bridges representing a typical al bridge inventory.