Comprehensive Bridge Health Evaluation Method Based on Information Fusion

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1 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ Comprehesive Bridge Health Evaluatio Method Based o Iformatio Fusio Li-pig Li 1,a, We-xia Dig 2 ad Xiao-li Lu 3 1 Faculty of Egieerig, Chia Uiversity of Geosciece, Wuha, Chia 2 Hubei Commuicatios Techical College, Wuha, Chia 3 Wuha Uiversity of Egieerig Sciece, Wuha, Chia Abstract. I the bridge maiteace maagemet decisio, the health evaluatio o bridge structure is far more tha determiatio of abormal idex exceed fixed threshold, or evaluatio o damage status ad carryig capacity, the o-site huma ispectio should also be paid attetio. I order to achieve more accurate ad reliable health status evaluatio result, it eeds to take full advatage of various iformatio ad parameter. The D-S evidece iformatio fusio was used i the paper to preset comprehesive bridge health evaluatio method. It fuses bridge operatio status usig abormal status idetificatio, bridge durability with residual life estimatio, as well as huma ispectio ratig, to arrive at health evaluatio. The actual applicatio examples to verify the method is also provided. 1 Itroductio The safety evaluatio i bridge structural health moitorig is always oe of the research focuses. Due to professioal differece, the work of two mai parts as iformatio acquisitio ad safety assessmet i structural health moitorig is completed by persoel of iformatio sciece ad mechaics sciece respectively. As a result, the existig structural safety assessmet theory is limited to the mechaics field. Most methods deped o accurate structural model ad kow excitatio system heavily. The safety assessmet is achieved with reductio degree of structural stiffess [1, 2]. The health safety assessmet of bridge always regards structural damage idetificatio as premise, amely firstly determie existece of damage ad locate it, the evaluate safety status of structure with stiffess reductio. I the existig bridge structure safety assessmet methods, most deped o sigle parameter as the evaluatig idex, such as bridge damage or durability. As to complexity of bridge structure ad eviromet, as well as radomess of measuremet result, the evaluatio evidece is always iadequate. It is impossible to accurately describe overall status of bridge structure, or eve arrive at wrog evaluatio result, so it has ot high cofidece for evaluatig with sigle parameter [3, 4]. Some researchers proposed multi-parameter evaluatio method ad achieved satisfactory effect. Therefore, it is a valuable focus to perform overall evaluatio o bridge status i accordace with acquired data from sesors as well as various parameter usig iformatio fusio method [5]. a Correspodig author: llpok795@163.com. The Authors, published by EDP Scieces. This is a ope access article distributed uder the terms of the Creative Commos Attributio Licese 4.0 (

2 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ The paper combies various parameter of bridge health status with iformatio fusio method to arrive at overall assessmet o bridge. The rest of the paper is orgaized as follows: Sectio 2 itroduces D-S evidece theory of iformatio fusio; Sectio 3 gives comprehesive health evaluatio method based o multiple iformatio fusio; Sectio 4 ad 5 preset the computatio example ad the coclusio. 2 D-S Evidece Theory Suppose as idetificatio framework. If the set fuctio m :2 [0,1] meet m( ) 0 ad ) 1, m is called the basic cofidece distributio o framework. As to A, m(a) is A the basic cofidece distributio value. I order to obtai total cofidece of A, it eeds to add the basic cofidece distributio value of all subsets B i A, ad the represet it with cofidece fuctio. Assume as a idetificatio framework, the set fuctio B : 2 el [0,1] is cofidece fuctio if ad oly if it meets coditios as followig: (a) Bel ( ) 0; (b) Bel ( ) 1; (c) To A1, A2,, A, there is 1 el i el i el i j ( el i i 1 i1 i1 ij B Y A B ( A) B ( A A ) ( B ( A) ( Set B el1 ad B el 2 as two cofidece fuctios o same idetificatio framework, m 1 ad m 2 as correspodig basic cofidece distributio. Set m1( Ai) m2( Bj) 1. AiBj The, the fuctio defied by followig is the basic cofidece distributio of fuctio m :2 [0,1], 0, A ) m1( Ai) m2( Bj) AiBj, A 1 m1( Ai) m2( Bj) AiBj Bel,, Bel As to sythesis of multiple cofidece fuctios, set 1 B as cofidece fuctio o the uified framework, m, 1, m as correspodig basic cofidece distributio, if Bel1 B el exists ad the basic cofidece distributio is m, as to A, A, there is: ) k m1( A m ( A ), (3) 1 A1,, A A1 A = A where, k m1( A m ( A ). A1,, A A1 A A It ca be see from ( ad (3) that the combiatio of multiple evideces has othig to do with order. The computatio of multiple evidece combiatio ca be obtaied by recursive computatio of two evideces [6]. ( 2

MATEC Web of Cofereces 82, 03003 (2016) DOI: 10.1051/ mateccof/20168203003 3 Comprehesive Safety Assessmet Based o Multiple Iformatio Fusio 3.

3 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ Comprehesive Safety Assessmet Based o Multiple Iformatio Fusio 3.1 Evaluatio Flow The evaluatio flow of the proposed method is show i Fig. 1. Figure 1. Multiple iformatio fusio evaluatio flow. 3.2 Evidece Trasformatio of Evaluatio Iformatio As to comprehesive bridge health evaluatio, its health status is a problem of data fusio, icludig statuses of health, uhealthy ad ucertai. The paper costructs idetificatio framework { A1, A2}. The shows the structure is i safe state ad i usafety status, so the ucertai status is m( ). It is also a importat i the iformatio fusio to represet above evaluatio results i the probability form ad complete cofidece distributio of differet evaluatio iformatio Evidece Trasformatio of Abormal Status Evaluatio The abormal status evaluatio o bridge usually determies whether some idicator exceed a fixed threshold. The abormality degree of structure ca also be obtaied by computig idicator deviatio from ormal value. Due to complexity of structure itself ad surroudig eviromet, it is quite difficult to determie a fixed evaluatio threshold. If the ispectio idicator is exactly equal to or close to the threshold, it is difficult to determie abormal structure. The Expoetially Weighted Movig Average (EWMA) cotrol chart was selected for bridge structure safety evaluatio usig moitorig iformatio statistical aalysis [7], Double cotrol threshold alarmig method was preseted, amely prelimiary alarm ad safety alarm. Referrig to the EWMA cotrol chart theory, the paper proposes double threshold abormal status evaluatio method, amely prelimiary threshold mi ad alarm threshold max. To address the bridge structure abormal determiatio, the system uses threshold as: 4. (4) I order to improve accuracy of structural abormal determiatio, as well as reduce the difficulty whe the detectio idicator is close to, the experieces ca be used to set prelimiary threshold mi 4, alarm threshold max 6. I accordace with the double threshold evaluatio method ad bridge maagemet experieces, if the idicator obtaied from abormal diagosis system is withi the rage of prelimiary threshold, it may be cosidered 0.8, 0.0 ad m( ) 0.2. Whe the detectio idicator is beyod the alarm threshold, it ca be cosidered 0.0, 0.8 ad m( ) 0.2. If the 3

4 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ idicator is betwee above thresholds, it ca be cosidered 0.33, 0.33 ad m( ) Evidece trasformatio of bridge durability The bridge durability aalysis ca be obtaied from durability of mai structure. Boom is the key compoet to coect arch ad road i the middle or low arch bridges. Its remaiig life ca be estimated from daily fatigue damage ad cumulative damage degree. I order to evaluate fatigue durability of boom, the cumulative damage as well as relatioship betwee remaiig life ad theoretical life should be used. The computatio method cosiders ot oly cumulative damage of boom, but also effect of recet vehicle load o fatigue life. As the boom is force key of log spa arch bridge, it directly affects the safety of arch bridge. The boom with the poorest durability ca be used as basis to determie durability of bridge booms. Represet the theoretical life is N ad remaiig life obtaied from fatigue estimatio as. The proportio relatioship betwee estimated remaiig life ad theoretical remaiig life as show i (5) ca be used to evaluate durability referrig to classificatio boudaries i the bridge level maiteace specificatios. The correspodig cofidece distributio ca also be determied. (5) N I accordace with bridge level classificatio boudaries, the cofidece distributio based o is show i Table 1. Table 1. Boom durability cofidece distributio. m( ) Evidece trasformatio of huma ispectio ratig The traditioal bridge health moitorig system is overly depedet o data acquisitio system, but despise huma ispectio. As the health moitorig system oly deploys sesors o some key compoets, so the sesor etwork caot cover whole bridge. The ucovered sites are usually blid area for safe operatio of bridge, while regularly ecessary ispectio may supplemet above corers of health moitorig system. Therefore, it is very importat of huma ispectio to health evaluatio. As to bridge health moitorig i the paper, huma ispectio is also desiged, such as regular testig o liear betwee rib ad deck, settlemet of piers, as well as corrosio crackig of compoets. The cofidece distributio of huma ispectio is always based o experieces. After each time of huma ispectio, the techical coditio ratig ca be obtaied from maagemet departmet. The correspodig cofidece distributio based o bridge ratig is show i Table 2. Table 2. Cofidece distributio of huma ispectio status evaluatio. Bridge Level m( ) First Secod Third Fourth ad fifth

5 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ Comprehesive Evaluatio Example Before safety assessmet, it should firstly acquire eeded data from correspodig database i accordace with evaluatio eeds. The evaluatio amout ca be obtaied after iformatio preprocessig. The prelimiary result of bridge abormal status, boom durability ad huma ispectio will be trasformed ito correspodig evidece. The comprehesive assessmet result ca be achieved after D-S evidece fusio. As the abormal status diagosis system is a ear real-time system, the bridge is performed 6 time of abormal diagosis per miute. The boom lifetime computatio updates oce per day. Limited by factors, the update frequecy of huma ispectio is ucertai. The maximum value of bridge status ovelty idicator i each miute is used as basis for status scorig. The boom fatigue status ratig ad huma ispectio scorig are based o latest assessmet. Takig moitorig data of some bridge as example, the detectio idicator data i early oe hour is show i Fig. 2. Figure 2. Overall status detectio idicator. As show i Fig. 2, most detectio idicators i the oe hour are ormal except for 5 poits betwee prelimiary threshold ad alarm threshold, 1 poit larger tha the alarm threshold. It idicates that the bridge is ormal i most of time. The sesor error or overload vehicles may temporarily impact o bridge structure. The moitorig idicator returs to ormal after abormal time poits, which idicates the overall bridge structure is i good coditio. I accordace with computatio result of daily damage, cumulative damage ad remaiig life of boom, the shortest remaiig life of booms is 26.5 years. It ca be regarded as the basis for boom durability determiatio. As the theoretical fatigue life of boom is 30 years ad it has worked 1.25 years, the theoretical remaiig life is years. Based o (5), N It idicates the bridge boom durability is ormal ad the cofidece distributio is 0.8, 0.0 ad m( ) 0.2. Based o latest bridge maiteace report ad scorig result of maagemet departmet, the bridge is i the secod-class, so the cofidece distributio is 0.7, 0.2 ad m( ) 0.1. Coduct D-S evidece fusio o abormal status evaluatio combiig with boom durability ad huma ispectio result, the overall safety assessmet ca be arrived as show i Table 3, Table 4 ad Table 5. Table 3. Overall bridge evaluatio whe the detectio idicator is less tha prelimiary threshold. Evidece m( ) Abormal status evidece Durability evidece Huma ispectio evidece

6 MATEC Web of Cofereces 82, (2016) DOI: / mateccof/ D-S fusio evidece m Table 4. Overall bridge evaluatio whe the detectio idicator is betwee prelimiary threshold ad alarm threshold. Evidece m( ) Abormal status evidece Durability evidece Huma ispectio evidece D-S fusio evidece m Table 5. Overall bridge evaluatio whe the detectio idicator is larger tha alarm threshold. Evidece m( ) Abormal status evidece Durability evidece Huma ispectio evidece D-S fusio evidece m Accordig to actual sitig ispectio, the bridge is i good operatio, which is cosistet with evaluatio result obtaied from comprehesive bridge safety evaluatio based o D-S evidece fusio method. 5 Coclusio Usig D-S evidece fusio method, the paper achieves comprehesive bridge safety assessmet fusig operatio status, durability ad huma ispectio result. The accuracy of health safety assessmet ca be improved. However, the paper does ot cosider weight i the proposed method. I the later research, the D-S evidece theory should be thoroughly studied ad weight of each evidece be studied, so as to further improve accuracy of safety assessmet. Refereces 1. Abdelfateh Kerrouche, J. Leighto, W. J. O. Boyle, Y. M. Gebremichael, Strai Measuremet o a Rail Bridge Loaded to Failure Usig a Fiber Bragg Gratig-Based Distributed Sesor System, IEEE Sesors Joural, vol. 8, o. 12, (2008) 2. Victoria J. Hodge, Simo O'Keefe, Michael Weeks, Athoy Moulds, Wireless Sesor Networks for Coditio Moitorig i the Railway Idustry: A Survey, IEEE Trasactios o Itelliget Trasportatio Systems, vol. 16, o. 3, (2015) 3. Zhou Jiatig, Huag Hami, Huag Shaglia, Che Weimig, Remote Real-time Health Moitorig ad Evaluatio System for Log Bridge Structure, Proceedigs of IMACS Multicoferece o Computatioal Egieerig i Systems Applicatios, vol. 2, (2006) 4. Yu Chogchog, Zhag Jia, Ta Li, Wag Jiya, Distortio data research of bridge structure health moitorig based o LS-SVM classificatio, Proceedigs of 3rd Iteratioal Coferece o Iformatio Scieces ad Iteractio Scieces (ICIS), (2010) 5. F. Bruschetta, D. Zota, C. Cappello, R. Zadoii, Fusio of moitorig data from cable-stayed bridge, Proceedigs of IEEE Workshop o Evirometal Eergy ad Structural Moitorig Systems (EESMS), 1-6 (2013) 6. La ji-hui, Ma Bao-hua, D-S evidece reasoig ad its data fusio applicatio i target recogitio, Joural of Tsighua Uiversity, vol. 41, o. 2, ( Qi Pig, Coditio assessmet based o coitegratio ad multivariate cotrol chart for largespa bridges, Chogqig Uiversity, (2015) 6

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