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1 Lehigh Univesity Lehigh Peseve Fitz Laboatoy Repots Civil and Envionmental Engineeing 1987 Weigh-in-motion and esponse study of fou insevice bidges, U.S. Depatment of Tanspotation, Fedeal Highway Administation Publication No. FHWA/RD-86/045, Octobe 1987, 200p. (87-20) J. H. Daniels J. W. Wilson B. T. Yen L. Y. Lai Follow this and additional woks at: Recommended Citation Daniels, J. H.; Wilson, J. W.; Yen, B. T.; and Lai, L. Y., "Weigh-in-motion and esponse study of fou insevice bidges, U.S. Depatment of Tanspotation, Fedeal Highway Administation Publication No. FHWA/RD-86/045, Octobe 1987, 200p. (87-20)" (1987). Fitz Laboatoy Repots. Pape This Technical Repot is bought to you fo fee and open access by the Civil and Envionmental Engineeing at Lehigh Peseve. t has been accepted fo inclusion in Fitz Laboatoy Repots by an authoized administato of Lehigh Peseve. Fo moe infomation, please contact peseve@lehigh.edu.

2 FRTZ ENGNEERNG UBORATORY LBRARY Pepaed Fo u. s. Depatment of Tanspotation Fedeal Highway Administation Office of Reseach and Technology Washington, D. c., WM+RESPONSE STUDY OF FOUR N-SERVCE BRDGES By.J. Hatley Daniels John L. Wilson L. Y. Lai R. Abbaszadeh B. T. Yen Depatment of Civil Engineeing Fitz Engineeing Laboatoy, Bldg. No. 13 LEHGH UNVERSTY Bethlehem, PA., Mach 1986 Fitz Engineeing Laboatoy Repot No

3 ACKNOWLEDGMENTS This eseach was caied out by Fitz Engineeing Laboatoy, Depatment of Civil Engineeing, Lehigh Univesity, Bethlehem, PA. D. win Kugelman is Chaiman of the Depatment of Civil Engineeing. The eseach epoted heein is pat of an investigation entitled "Stuctual Evaluation of n-sevice Bidges Using WM Technology" sponsoed by the Fedeal Highway Administation. (FHWA) Washington, D. C. The poject supeviso and contacting office's administative epesentative (COTR) fo the FHWA is M. Haold Bosch. The authos gatefully acknowledge the extensive assistance eceived in the conduct of the field studies and in the pepaation of this epot. Helping in the field wee Messes. Jian Jin, Sun Hwang, Chia-Ming Lu, and mad A. Alwan who opeated the WM+RESPONSE data acquisition system duing the long aftenoon and night shifts. Messs. Hugh Sutheland, Russel Langenbach and Dan Pense wee esponsible fo the installation of the stain gage tansduces, stain gages and wiing at the bidge site and the coect connections to the WM+RESPONSE system. The field studies would not have been possible without the coopeation and expet assistance of pesonnel fom the Pennsylvania Depatment of Tanspotation (PADOT) Distict 5-0. The authos acknowledge the excellent coopeation and assistance eceived fom M. Robet Donovan, Bidge Enginee, and M. Ed McCann, Assistant Distict Enginee-Maintenance. Special thanks ae due M. Jim Hoegg, Maintenance nspcto, whose pesence and assistance in the field duing the field studies was absolutely necessay. He povided that vey vital liaison between Distict 5-0 and the Lehigh Univesity eseach team. Many thanks also to the Distict 5-0 pesonnel in Lehigh and Nothampton Counties who povided the sign cews and equipment needed at each bidge site, and without whose help the field wok would not have gone so well. The manuscipt was typed with cae by Magaet Swallop and Gealdine Key. The figues wee pepaed by John M. Gea and Shaon Balogh. i

4 Appoximate Convesions to Motic Me1sues METRC CONVERSON FACTORS Ul - C't N = Appoximate COlvenions hom Metic Measues Symbol When Vou Know Muhiply by To find Symbol - e Symbol When Vou Know Multiply by To Find Symbol LENGTH N Cll 2 = D LENGTH =-- N = - n... in inctln "2.5 centilnltes em =.... mm lftillimetes 0.04 lnchn ft Mt 30 cantimtea em -.. em centimetes 0.4 lnchn. n vel yads 0.9 metes m -;----!iil_ Cll m _. :u... t -... mi miles 1.6 kilo Ntes km ll met vel km kiiorm«es AREA Ul AREA = in 1 quae inches uaa centilnltea. em ll i5 P h' quae tnt 0.09 quae metes m -==--... cm 1 quae centimetes 0.16 MU'ainchn n' vel' MUia yads 0.8 quae mete m' m'. Mlua metes,1.2 Muaayada yd' mi' 1qua1a miles uaa kilometes km 1 ==... km 1 aquaa kilomete 0.4 aquaa miles ml hi == tkta m ' - =... -' MASS (weight) m MASS (weight) N =-... = 01 ou- 28 gama gama ou- 01 =-... lb pounds 0.45 kilogama kg kiiogama 2.2 pounda lb lhot tons 0.8 ton- D t = "' to-nooo ktl 1.1 lhot tons lbl --- s VOLUME VOLUME - -- = Tb..,i tablaspoona 15 millilites ml - = lites 1.06 quana qt m fl 01 fluidou- 30 millilites ml lites 0.26,.lona gal hec:laf - C't he w - ml millilites 0.03 fluid ounces 01 lip tuspoons 6 millilites ml L... litea 2.1 pints pt c cups 0.24 lites - = m cubic metes 36 cubic fmt lt 1 pt pints 0.47 lites N - qt quats 0.96 lites &; -=-- 1ft m cubic- 1.3 cubic yads yd' pi pllona 3.8 lites - TEMPERATURE Cexacd ft' cubiclnl 0.03 cubic metes m vel' cubic yads 0.76 cubicmet n m.. - = tempeatue add 321 f'l c Celsius 8/ilthen Fahenheit., TEMPERATURE (exac:t) ' S- tempeatue - N : == 5 tempeatue subtacting tempeatue -.,., OF Fahenheit 619 lah Celsius c 3iiil.- E... 1 in 2.54 leuclly). Fo othe euct conylions and moa detailed table1;- NBS t i.!».'..'-:a, lio 10 \00 Miac:. Publ. 286, Unit1 of Weighla and Mee111es, Pice $2.25, SO Catalog No. C13. \0:286. c 31 c

5 TABLE OF CONTENTS 1. NTRODUCTON 1.1 Backgound 1. 2 Objectives 1.3 Scope of Wok 2. LOAD AND RESPONSE NFORMATON NEEDS 2.1 Oveview of Load and Response Studies Bidge Loading Stop-and-Weigh Studies Weigh-in-Motion Studies Bidge Response Analytical Studies Field Studies 2.2 nfomation Needs Bidge Loading Bidge Response 2.3 nfomation Obtained in This Study 3. PROTOTYPE WM+RESPONSE SYSTEM 3.1 Oveview of FHWA WM System 3.2 WM+RESPONSE System Design Paametes 3.3 Modification of FHWA WM System 3.4 WM+RESPONSE System Documentation 4. FELD STUDY BRDGES 4.1 Bidge Selection Citeia 4.2 Desciption and nstumentation EB Route 22 Ove 19th St WB Route 22 Ove 19th St NB Route 33 Ove Van Buen Rd NB Route 33 Ove State Pak Rd. 5. RESULTS OF FELD STUDES 5.1 Data Pocessing 5.2 EB Route 22 Ove 19th St. iii Page

6 5.2.1 GVW Distibution Stess Range Distibution Stain Rate Distibution Maximum Stess vs GVW 5.3 WB Route 22 Ove 19th St GVW Distibution Stess Range Distibution Stain Rate Distibution Maximum Stess vs GVS 5.4 NB Route 33 Ove Van Buen Rd GVW Distibution Stess Range Distibution Stain Rate Distibution Maximum Stess vs GVW 5.5 NB Route 33 Ove State Pak Rd GVW Distibution Maximum Stess vs GVW 5.6 Discussion of Field Study Results GVW Distibution Stess Range Distibution Maximum Stess Range and Maximum Stess Stess Range vs GVW Stess Range vs Stain Rate 6. RESULTS OF ANALYTCAL STUDES 6.1 Desciption of Analytical Studies 6.2 EB Route 22 Ove 19th St. 6.3 WB Route 22 Ove 19th St. 6.4 NB Route 33 Ove Van Buen Rd. 6.5 NB Route 33 Ove State Pak Rd. 6.6 Discussion of Analytical Results Stess Range Ratios ( a Ratios) Compaison of Field Study and FE Stesses Compaison of Field Study and AASHTO Stesses 7. SUMMARY AND CONCLUSONS 8. REFERENCES iv Page

7 1. NTRODUCTON 1.1 Backgound Highway bidges sustain vehicula taffic which vaies in weight, oveall length, numbe of axles, axle spacing, speed and dynamic chaacteistics. The volume and conditions of taffic such as headway and multiple pesence, as well as the coelat.ion of taffic with bidge type, geomety, configuation and othe factos, such as maintenance, detemines the integity and life expectancy of highway bidges and thei components. Fo any paticula bidge the static and dynamic esponse to a vehicle can be accuately monitoed and evaluated if the geometical and loading chaacteistics of the vehicle ae known. Until ecently it has not been possible to detemine, to a easonable degee of accuacy, the chaacteistics of vehicles cossing a bidge unde actual highway conditions. Consequently, expected damages, if any, by vehicula taffic could not be accuately estimated. nspection of bidge supestuctues thoughout the U.S. eveals that some degee of damage does exist. A numbe of steel bidges have expeienced fatigue cacking, some of them even lage factues of steel components. ( )* Many othe bidges have expeienced coosion damage, buckling of plates and membes, connection distess, and undesiable cacking of einfoced and pestessed concete membes. These kinds of damages can be attibuted most fequently to high loads, excessive taffic volume, poo maintenance, faulty design, inadequate specifications, o a combination of these. While geat advances have been made, fo example, in the aeas of ( ) fatigue, factue and stength of steel bidge components, ' ' ' ' estimates of the fatigue stength and expected sevice life of in-sevice steel bidges have been caied out fo only a limited numbe of cases. (11,12,13,14,15) Even in these cases, confidence in the estimates is not high. This is because, although stesses in citical components can be accuately measued as vehicles tavese the bidges, the geometical and * Refeences ae listed in Chapte 8 of this epot. -1-

8 loading chaacteistics of vehicles cossing the bidges could not be accuately measued but only estimated at the time of the studies. n ecent yeas significant advances have been made in the develop-. (u ment of weigh-in-motion M) (16,17,18,19,20) h w systems. T e WM sys ten,_ developed fo the FHWA by Case Westen Reseve Univesity is potable and utilizes an existing bidge to seve as an equivalent static weigh scale to obtain not only goss vehicle weights (GVW) but also axle weights and spacings, as well as speeds of vehicles cossing the bidge at nomal highway speeds. ( ) Unde FHWA sponsoship thee WM systems wee built and used to weigh moe than 27,000 tucks in seven states. (l 9 ) Since the weighing opeation cannot easily be detected by tuck dives the esults ae not subject to the usual bias associated with taditional tuck weighing methods. Both loadomete suveys.and weight data fom weigh stations ae subject to bias because illegal tucks can easily avoid an opeating weigh tation with the aid of CB adios. The WM system data has begun to eveal the tue spectum of tuck loads, especially the extent of the high loads which ae causing significant bidge damage. The studies epoted in Ref. 19 also indicate that accuate tuck weights ae obtainable with the WM system. Cuent analysis and design of highway bidges in the U.S. is based on the AASHTO H (M) and HS (MS) tuck and lane loads. ( ) These "standad" AASHTO live loads have emained basically unchanged fo ove 40 yeas. The H (M) loadings wee intoduced in 1924 (See ASCE Tansactions, 1924, pp ) and"adopted by AASHO in thei fist edition, The HS (MS) loadings wee intoduced in the thid edition of AASHO, These live loads do not epesent the majoity of moden tucks using todays highway system. n the intevening yeas the weights of tucks and thei fequency. of occuence have inceased significantly. Many states have esponded by aising thei design loads, say fom HS 20 (MS 18) to HS 25 (MS 22.5). Some states also check thei designs by compaing with the heaviest pemit vehicles authoized in thei state. With the developmet of the FHWA WM system it is now possible to obtain elatively unbiased statistical data on tuck speed, configuation, loading and fequency of occuence and to update that data. This infomation can be used to develop moe ational "standad" design tucks fo use in bidge design and ating ( 23 ) pocedues. -2-

9 Much moe can be done, howeve, with the WM system. By coupling the WM system with a system fo measuing stains in bidge components, data on bidge esponse can be achieved at the same time that loading data is being obtained fom all the vehicles cossing the bidge within an abitay peiod of time. Fo n evaluation of bidge esponse the pimay infomation equied is the magnitude and vaiation.of stess in bidge components duing passage of vehicles ove the hidge. The coelation of goss vehicle weight (GVW), axle weights and fequency with stess ange and induced maximum.stess is the foundation of simple bidge design pocedues and specifications. based on stength and seviceability (such as fatigue) equiements. This epot pesents the esults of a 30 month eseach investigation conducted at Lehigh Univesity, Bethlehem, PA duing which one of the FHWA WM systems was edesigned and used to obtain simultaneous load and esponse data fom 19,402 tucks cossing fou in-sevice bidges. The edesigned system is designated the WM+RESPONSE system thoughout this epot. 1.2 Objectives The oveall contact objectives of this investigation ae "to detemine what bidge esponse infomation and tuck loading is necessay fo a detailed evaluation of stuctual pefomance" of bidges and to "develop methods fo using weigh-in-motion (WM) technology to obtain the equied data". Specific objectives included the following: 1. Review existing bidge loading and esponse infomation and detemine the specific needs which will enable an effective evaluation of stuctual pefomance and emaining sevice life. 2. Review weigh-in-motion technology, specifically the FHWA WM system hadwae and softwae. 3. Redesign the FHWA WM system hadwae and softwae to enable tuck loading and bidge esponse data to be obtained simultaneously fom insevice bidges. 4. Constuct a WM+RESPONSE system complete with the hadwae and softwae equied to acquie and stoe stain data fom in-sevice bidges and to pocess that data to obtain simultaneous load and esponse infomation. -3-

10 5. Use the WM+RESPONSE system to acquie and pocess simultaneous load and esponse data fom seveal in-sevice bidges. 6. Evaluate the load-esponse infomation obtained,fom the in-sevice bidges by compaing actual field esults with analytically obtained esults and with esults of analyses based on the AASHTO specifications. 7. Documentation of the WM+RESPONSE system hadwae and softwae and tansfe of the technology to the FHWA. 1.3 Scope of Wok Within the poject objectives listed in At. 1.2 of this epot the following scope of wok was accomplished. 1. Existing bidge loading and esponse infomation was eviewed and needs wee detemined fo steel an.d concete bidge supestuctues. Those needs ae listed and discussed in Chapte 2 of this epot. 2. The existing FHWA WM system hadwae and softwae wee studied. The WM system povided to Lehigh by the FHWA on Octobe 17,.1983 was used in July 1984 to weigh tucks cossing the Tilghman Steet bidge on Rte. 309 West of Allentown, PA. ( 24 ) An oveview of the FHWA WM system is povided in Chapte WM+RESPONSE system.design paametes wee developed based on the needs discussed in Chapte 2, the capabilities of the existing WM system, the poject time constaints and the poject financial esouces. Valuable input was obtained fom the esults of a pelimin?y load-esponse study conducted duing Septembe and Octobe 1984 using the Batonsvill.e bidge located on -80 nea Batonsville, PA. (l 6, 24 ) n that study a peliminay WM+RESPONSE system design was used to.weigh 329 tucks and simultaneously obtain stain data fom thee inteio gides. The development of the WM+RESPONSE system final design paametes is pesented in Chapte Based on these final design paametes the WM system povided by the FHWA was modified and a pototype WM+RESPONSE system constucted, complete with hadwae and softwae. The modifications to the WM system ae descibed in Chapte The pototype WM+RESPONSE system was used to.obtain simultaneous load and esponse data fom thee in-sevice steel aid one in-sevice pestessed -4-

11 concete bidge.supestuctues duing the sunnne of Duing 4 weeks of continuous day and night field opeation, simultaneous tuck weight and bidge esponse data wee obtained fom 19,402 tucks cossing the fou bidges. Desciptions of the field study bidges ae povided in Chapte Chapte 5 povides the esults of the load plus esponse studies. Details of data pocessing and a discussion of the field study esults ae also pesented. 7. Maximum gide stesses obtained in the field study ae compaed with the esults of finite element analyses of the thee-dimensional steel supestuctues in Chapte 6. n addition the actual and analytical gide stesses ae compaed with stesses computed using the assumptions and pocedues of the AASHTO Specifications, Thiteenth Edition. The chapte concludes with a discussion of the analytical esults. 8. Conclusions and ecommendations ae povided in Chapte The WM+RESPONSE hadwae.and softwae systems ae fully documented in Refs. 25 though

12 2. LOAD. AND RESPONSE NFORMATON NEEDS 2.1 Oveview of Load and Response Studies 2.1.i Bidge Loading Cuent pocedues fo the analysis and design of highway bidges in th U.S. use the AASHTO H (M) and HS (MS) system of tuck and lane loads which epesent "standad" single tucks.o tacto-and-semi-.. (21 22) taile configuations ' These tucks do not epesent the majoity of vehicles tavelling ove highway bidges. Actual vehicles ange fom small passenge cas to two, thee and fou-axle tucks, to five-axle (eighteen wheel) semi-tailes and to semi-tailes and tailes in tandem with. moe than five axles. Vehicle factos affecting bidge esponse include goss vehicle weight (GVW), the numbe of axles and thei spacing the distibution of GVW among the axles, vehicle speed, oveall vehicle length, tansvese position of the vehicle (lane), and he dynamic (bounce) chaacteistics of the axles. Also influencing bidge esponse ae the distances between vehicles in a given lane (headway), the occuence of vehicles in moe than one lane (multiple pesence), and the dynamic chaacteistics of the bidge. A numbe of studies have been conducted by the FHWA and individual state tanspotation depatments to detemine the configuation and weights of vehicles cossing highway bidges. Refeences 16 to 20 and 31 to 34 povide a bief oveview of some of the studies conducted ove the past twenty yeas. Typically two appoaches have been followed in studies of bidge loading: Stop-and-Weigh Studies Vehicles (usually tucks) ae stopped and weighed at off-highway opeating weigh stations situated at fixed locations along the nation's highways. Altenatively, vehicles ae stopped and weighed at andom locations along highways using potable axle (wheel) scales. This appoach has not been successful in detemining the vehicle paametes most affecting bidge esponse fo seveal easons. The majo poblem is that, -6-

13 with the aid of CB adios, most of the vey heavy (usually illegal) tucks can easily avoid an opeating weigh station. Only a few vey heavy tucks ae weighed, typically within the fist half hou o so afte a weigh station opens. Thus the high end of the tuck weigh spectum is missing fom the data even though it is known that a significant amount of. the stuctual damage obseved in bidges is due to tucks fom this pat of the spectum.anothe poblem is that the dynamic chaacteistics of a vehicle at est cannot be measued. n addition the inceasing costs of conducting stop-and-weigp opeations.pohibits thei widespead use Weigh-n-Motion Studies n-motion weighng techniques have been developed in the past 10 o 15 yeas. Reasonably accuate estimates of tuck weights, speeds, dynamic chaacteistics and othe infomation ae possible. Basically, thee types of weigh-in motion systems ae used: 1) pavement scales embedded in highways and on o off amps; 2) pavement o platfom scales located at offhighway opeating weigh stations; and 3) use of existing highway bidges seving as equivalent static weigh scales. The fist two systems have not poved successful fo detemining most of the vehicle paametes affecting bidge esponse. The fist suffes fom a numbe of poblems, such as, inaccuacies associated with the "bounce" chaacteistics of the elatively light scale, change in the bounce chaacteistics of the scale with time, maintenance of the pavement scale, especially in colde climates, and the need to fequently esuface the pavement in the vicinity of the scale. n addition, analytic poblems ae encounteed in computing bidge esponse using the infomation obtained fom a pavement scale. The second system suffes fom some of the above poblems plus the majo poblem associated with stop-and-weigh stations, that is, the avoidance of the weigh station by the vey heavy tucks. The thid system, although not pefect, is poving to be the most effective means of diectly obtaining the vehicle paametes most affecting bidge esponse pimaily because the weighing opeation cannot easily be detected by tuck dives and data is obtained while vehicles coss the bidge at nomal highway speeds. The FHWA WM system, fo example, can -7-

14 obtain faily accuate estimates of GVW, axle. weight, axle spacing and speed fo individual tucks cossing a bidge in any lane. (l 9 ) Ongoing impovements to the system should enable sepaate tuck infomation to be obtained when multiple vehicles coss the bidge in the same o paallel lanes Bidge Response Numeous bidge esponse studies have been undetaken, pimaily duing the past twenty yeas. This span of time coincides with the continuing developments in compute hadwae and softwae which ae making it inceasingly ossible to acquie and pocess the vey lage amounts of infomation associated with ealistic bidge esponse studies. Refeences 1 to 5, and efeences 11, 13, 14 and 35 to 39 povide a bief oveview of some of this wok. Typically two appoaches have been followed in studies of bidge esponse Analytical Studies The esponses of any bidge supestuctue to vehicula loads involves the complex inteaction of all elements compising the supestuctue. n a multiple gide bidge, fo example, these elements typically include the gides, diaphagms, and deck. n a two-gide bidge they include the gides, floo beams, stinges, diaphagms and/o coss bacing, lateal bacing and deck. The AASHTO Bidge Design Specificati-ons and typical office design pocedues ae outgowths of the pe-compute ea whee complex stuctual systems of necessity had'to be dastically simplified fo outine manual analysis and design. Manual analysis of the simplest supestuctue unde assumed static loading conditions is extemely difficult. Manual analysis consideing the eal dynamic loading conditions is vitually impossible to pefom. Actual supestuctue stesses and defomations ae usually quite diffeent fom those calculated in design. n addition, stesses ae not calculated fo many of the elements compising the supestuctue. Conside, fo example, the design of a steel multiple gide bidge. Live load and impact ae distibuted to a gi,de in popotion to the assumed -8-

15 design load intensity ("standad" H (M) o HS (MS) loading) and gide spacing. The esulting design stesses ae typically somewhat lage than the measued stesses unde the eal vehicula. loads. On the othe hand stess calculations ae not nomally pefomed fo diaphagms o thei connections to the gides. Measued displacement induced stesses in the vicnity of connections fequently exceed the specified allowable static and/o fatigue stesses. This situation is often much wose fo two-gide bidges. ( 5, 35 ) Fom a static stength point of view such design pocedues have poduced athe good esults based on the limited numbe of stength elated failues expeienced to. date. Howeve, fom a fatigue stength point of view, the level of.pefomance is not so good. Refeence 39 points out that appoximately half of the failues epoted in a ecent suvey ae attibuted 'to fatigue with most of the failues elated to the connections. Recent analytical studies of bidge esponse ecognize the need to pefom moe sophisticated compute analyses (usually finite element analyses) of the supestuctue in ode to obtain a bette estimate of stesses and displacements. Field measuements unde contolled loading conditions (usually test tucks of known axle weights and spacings tavelling at cawl speeds o in fixed locations on the deck) have confimed (5 '14) the validity of such analyses. Although useful in bidge esponse eseach this appoach is not pactical o even possible in the outine evaluation (ating) of existing bidges o the design of new bidges. Although compute capabilities have inceased enomously ove the past decade it is unlikely that the eal spectum of dynamic loading conditions can be consideed in the nea futue. Even if this wee possible it is not pactical to collect taffic data and undetake complicated analyses on a bidge-by-bidge basis to assess existng bidges fo damage by maximum stess o fatigue. Fo new bidge design simplified but easonably accuate analytical techniques ae needed, coupled with statistical infomation on cuent and pojected taffic type and volume. n addition new and impoved specification povisions ae needed which ae compatible with these techniques. -9-

16 ' Field Studies An altenate and moe diect method of obtaining bidge esponse infomation is by measuements of actual stains and displacements of in-sevice bidges. Bidge esponse to vehicula loading is a diect esult of those loads. The effects of all influencing factos ae aleady included in the esponse measuements. These factos include all paametes associated with the.loading such as vehicle type and volume, lane position and speed. All paametes associated with the supestuctue ae also included. These include span length, configuation of gides, floo beams, stinges, diaphagms and coss bacing, lateal bacing, and deck, as well as alignment (tangent o hoizontally cuved) supeelevation, gade and deck oughness. A lage numbe of bidge espnse studies of in-sevice bidges have been made especially duing the past twenty yeas. (ll) Most of these have been stess histoy studies which geneate statistical infomation on actual maximum stesses and stess anges at citical details. Although accuate stess histoy data has been poduced in these studies, it was not possible to also obtain simultaneous statistical infomation on the vehicula loading chaacteistics which poduced the stess histoy data. All studies, of necessity, wee foced to ely on estimates of taffic chaacteistics fom othe souces, maiily loadomete suveys conducted on the same o simila taffic outes. This is because, until now, a compute system capable of acquiing, stoing and pocessing simultaneous load and esponse infomation has not been available. This epot pesents the esults of an investigation in which a WM+ RESPONSE compute system was designed, built and used in field studies of fou in-sevice bidges to obtain simultaneous load and esponse data which was used to study and evaluate the behavio of these bidges unde the nomal taffic conditions. 2.2 nfomation Needs Bidge Loading mpoved designs of new bidges and impoved evaluations of in-sevice bidges (opeating and inventoy atings), whethe fo stength o seviceability, ae diectly dependent upon accuate infomation on bidge -10-

17 loadings. Some specific needs ae pesented as follows: 1. Accuate statistical infomation on, bidge loading specta is needed as the foundation fo pobabilistic based design pocedues. (l 9 ) 2. A complete bidge loading model fo stength design o ating equies statistical infomation on individual tuck weights, axle weights, axle spacings, impact levels,.tuck headway and multiple pesence. (l 9 ) 3. Seviceability design o ating models. equie statistical infomation on individual tuck weights, impact levels and fequency of occuence fo long spans (main gides) and axle weights, impact levels and fequency of occuence fo shot spans (floo beams, stinges and dec). (ll, 35 ) 4. mpoved specification povisions applicable to edundant vesus nonedundant bidges o design pocedues to ensue edundancy ae dependent upon non-linea collapse studies of bidges. These studies ae dependent upon impoved infomation on bidge loading and dead load to total load aios. ( 39 ) 5. mpovements to the "Bidge Fomula" equie accuate infomation on the bidge loading spectum and an impoved bidge loading model. ( 4 0) Bidge Response mpoved designs of new bidges and evaluations (atings) of insevice bidges, whethe fo stength o seviceability, ae diectly dependent on the ability to accuately pedict the esponse (stains, displacements) of a bidge to the vehicula ioads (loading models o loading spectum). Some specific needs ae discussed as follows: 1. Stess Range Stess ange histogams have been developed using seveal diffeent counting techniques such as ascending, descending, esevoi, ainflow and peak-to-peak. (ll) The need fo this infomation is evident fom a eview of the efeences aleady cited, especially Refs. 5,6,9,11,21 and 35. Although it is ecognized that diffeent tuck positions geneate diffeent magnitudes of stesses at a given point and design pocedues do equie that "design tucks" be placed at maximum esponse positions, it is not widely ecognized that the stess ange histogam fo a point on a bidge is not diectly popotional to the GVW histogam fo the bidge. A eview of Chapte 5 of this epot will indicate the consideable diffeences -11-

18 between stess ange and GVW histogams. due to seveal factos such as: This non-popotionality is a) Not all tucks tavel in the positions which poduce maximum stess at a point. b) Vitually evey tuck is consideably diffeent fom the "design tuck" in axle spacing, numbe of axles, axle weights and GVW. c) Actual impact is diffeent fom the design impact. A eview of the vey limited field data available indicates that a simple analytical pocedue to coelate the stess ange and GVW histogams fo all points of inteest on a bidge is not likely to exist. This coelation can best be obtained though field studies of in-sevice bidges. 2. Stain Rate Chapte 14 of Ref. 10 discusses the ole of stain ate (stess ate o loading ate) in the development of the cuent AASHTO Bidge Specifica-. f 1.. (l4 ' 21).. d, 1'. t1on actue conta c1te1a. t 1s po1nte out tnat app 1cat1on of the loading ate (tempeatue) shift allows c athe than Kid to be the contolling paamete poviding fo the slqw to intemediate loading ates that ae expeienced in bidges. Coelation of bidge loading with esponse data will povide definitive infomation on the coelation. between type of bidge (simple span, continuous, numbe of gides, etc.) bidge loading and expected stain ates in main membes and details. Refeence 35 discusses the significance of loading ate and cack extension behavio.. with GVW A simple analytical pocedue to coelate stain o loading ates histogams fo all points of inteest on a bidge is not likely to exist. This coelation can best be obtained though field studies of in-sevice bidges. 3. Maximum Stess The coelation between maximum stess and bidge loading is needed fo seveal easons: a) To obtain the coelation between maximum design stesses in pimay membes and the actual maximum stesses unde actual taffic conditions. b) To obtain the coelation between actual vehicula loading and maximum stesses at details and in membes and details fo which analytical -12-

19 stesses ae not nomally available, o vey difficult to obtain. Most bidges, although constucted in thee-dimensional space,. ae analyzed and designed as two-dimensional plana stuctues. The actual stesses induced by consideing the actual supestuctue configuation which may consist of gides, floo beams, stinges, diaphagms, coss-bacing, lateal bacing and deck as well as details, such as floo beam to cantileve backet tieplates, and all othe details and connections actually pesent in the thee-dimensional stuctue, ae not known and not nomally calculated.c 5 ) c) Cuent studies of bidge edundancy as used in the fatigue povisions of the cuent AASHTO Specification would benefit geatly with data on the coelation of bidge loading and stesses poduced as a means of defining load paths. ( ) This coelation is also 1\eeded in the studies to effectively model a thee-dimensional bidge fo compute aided engineeing (CAE) analyses. ( ) d) Coelation between maximum stess and bidge loading is needed fo a (10,21,35) bette un d estan d ing o f f actue conto Load Distibution AASHTO citeia on the distibution of live loads have been continuously evised since the fist edition in Many of these citeia ae not based on ealistic infomation. A eview of the distibution citeia in the 13th Edition. Gl) indicate that they ae not unifom among bidge type. Refeences 38, 41 and 42 epot on load distibution studies in the past twenty yeas fo composite box gides and pesstessed concete bidges which wee based on moe ational and ealistic infomation. Since the late 1960's the NCHRP has made an effot to educe some of the inequities in load distibution citeia. Refeence 43 develops a synthesis of infomation on the distibution of wheel loads on highway bidges. This efeence indicates that a need exists fo field studies which will acquie eliable load-esponse infomation fo the pupose of calibating the vaious load distibution theoies. 5. Dynamic Effects Fom the ealiest days, the development of bidge design pocedues and specifications have been based on the assumption that a bidge which, in eality, esponds dynamically to the dynamic vehicula loads, can be designed fo static stength as though the bidge is a static system -13-

20 subjected to static loads but with the live load amplified by an impact facto to account fo the influence of the dynamic effects on stength. (Adjustments to allowable stess have also been made to account fo fequency of occuence and long span vesus shot span effects). Consideing only the static stength of a bidge this assumption has seved quite well in view of the vey low incidence of stength failues of bidges. Howeve, fom a seviceability point of view the design of bidges against fatigue, factue, concete cacking and deck deteioation, to name a few, which ae influenced by the long tem effects of dynamic loading and esponse, this assumption has not seved well, as evidenced by the inceasing numbe of in-sevice bidges both steel and concete which ae suffeing damage and failues attibuted to cyclic stess and dynamic effects. Refeence 44 states that' pehaps the single most impotant cause of lage dynamic esponse is the pesence of oadway uneveness on the bidge deck and appoach pavements as well as abupt discontinuities in level, as at joints and pot holes. Stess ange and stain ate infomation obtained fom load-esponse studies of in-sevice bidges includes the effects of dynamic loading and dynamic esponse. Howeve, thee is a need to pefom a lage numbe of field studies in ode to statistically evaluate the effects of vehicula loading, bidge type and deck oughness on stess ange and stain ate. Additional field studies ae needed to access the influence of dynamic effects on othe bidge design paametes. 2.3 nfomation Obtained in this Study t was not the intent of this study to exh.austively acquie and evaluate load and esponse data fo the pupose of poviding definitive solutions to all of the needs discussed in this chapte. Rathe the objective was to detemine what load and esponse infomation is needed fo a detailed evaluation of stuctual pefomance and to develop methods fo using weigh-in-motion technology to obtain the equied data. The pototype WM+RESPONSE system developed in this investigation and descibed in Cnapte 3 of this epot was designed to be able to acquie data elated to all of the needs addessed in this chapte. Of necessity, howeve, the pototype system was designed.to acquie esponse data fom -14-

21 a limited numbe of points on a bidge supestuctue. Futue impovements to the system would enable it to acquie data fom a lage numbe of points. Load and esponse data wee obtained fom fou in-sevice bidges and evaluated with.espect to GVW, stess ange, stain ate and maximum stess needs. Because of the limited capabilities of the pototype WM+RESPONSE system, evaluation of load distibution and dynamic effects, beyond the dynamic effects included in the s-tess ange and stain ate infomation, was. not possible. Consideation of load distibution equies a system capable of acquiing sufficient stain data to define the bending moment distibution fo all the gides in a coss section of a bidge. ( ) Fo example, a five gide bidge with a minimum of fou stain gages pe gide(to obtain a easonable estimate of the stain distibution in the gide) would equie a total of 20 channels of stain esponse input, exceeding the 16 channels available in the pototype system. Data fom all channels would have to be acquied simultaneously fo each load event in ode to define the load distibution. This equiement is not needed in studying stess ange, fo example, whee the numbe of stain gages can exceed the numbe of available input channels of the esponse system, since it is not necessay to acquie simultaneous data fom all stain gages fo each loading event. The WM+RESPQNSE system could be used in a futue load distibution study of fou gide bidges. f somewhat educed accuacy is acceptable, such as fo a pilot study, moe gides could be accommodated by using only two o thee gages pe gide. Dynamic effects wee consideed in this investigation in evaluating stess ange and stain ate data. Howeve, othe. dynamic effects, such as impact ae not consideed. Conflicting equiements encounteed in the design of the pototype WM+RESPONSE system endeed a study of impact in this investigation somewhat difficult. To.obtain accuate tuck weight infomation it is necessay to instument a bidge that has a elatively smooth deck.and smooth tansitions at expansion joints and appoaches. On the othe hand it is desiable to investigate impact fo bidges having elatively ough decks and abupt changes in level at expansion joints and appoaches.. f lod and esponse infomation is obtained by instumenting the same bidge (in the case of continuous spans) o the same span, both -15-

22 conditions can not be met at the same time. t would be possible to weigh tucks using one simple span and obtain esponse fom anothe simple span of the same bidge. Howeve, a combination of the two equied conditions is not likely to exist in the same bidge unless the ough conditions ae atificially ceated fo the esponse span. This investigation did not exploe these possibilities. -16-

23 3.1 Oveview of FHWA WM System 3. PROTOTYPE WM+RESPONSE SYSTEM Recognizing the limited success in weighing vehicles using pavement systems, the FHWA launched a seies of feasibility studies to ecommend altenative weigh-in-motion systems. < ) The appoach descibed in Ref. 46 which poposed using stain gages on main longitudinal bidge gides to weigh vehicles in motion was adopted by FHWA fo implementation. A complete desciption of the design of the esulting FHWA weigh-in-motion (WM) system and its use to weigh moe than 27,000 tucks in seven states ae contained in Refs. 19 and 20. povided in Ref. 48; opeation. The system softwae use's manual is Figue 1 shows the field equipment set-up fo a typical weighing The FHWA WM system consists of the following components. 1. Two tape switches ae placed in the ight lane (lane 1) of the appoach to the weighing span as shown in the figue. ae taped down to the pavement. passing lane (lane 2) of a two lane bidge. two metallic stips embedded in a ubbe casing. of contact in the nomal condition. The tape switches themselves Tape switches can also be placed in the The tape switch consists of The stips ae held out When a vehicle tie passes ove the tape switch the two stips ae foced into contact, effectively closing a switch. The tape switch must be held in place by taping it to the pavement. Tape switches cn be obtained in a vaiety of lengths. n this study 5 ft. (1.52 m) long Contaflex 171-lS tape switches wee obtained fom Tapeswitch Copoation of Ameica, Famingdale, N.Y., Odinay 2 in. (5.08 em) wie duct tape can be used to secue the tape switches to the deck and was used duing the Tilghman St. and Batonsville peliminay bidge studies (Aticle 3.2). Howeve, fo the main field studies (Chapte 4), 6 in. (15.24 em) wide, Type No. 672, Olive Dab tape, poduced by Pemacel, New Bunswick, N. J. was used. supplied to Lehigh by FHWA. Chapte 4. This tape was Tape switch installations ae discussed in 2. An optional keypad which can be used to tigge the system and to input data such as the lane in which the tuck is tavelling and the type of tuck. The keypad is not used when the system is in automatic mode and -17-

24 , ; -.. -, Ji:pe---- SWTCHES STRAN TRANSDUCERS -- \ _) (_, '-:-t:::::x:::--.. :-c::: The nstallation ncludes ( 1 ) tape switch axle detectos, (2) an optional key-pad to ecod tuck body type and othe visible hauling infonnation, (3) specially designed stain tansduces clamped to bidge gides, and (4) a mini compute complemented with dedicated electonic appaatus located in a mobile instumentation van, paked unde a bidge..;:-. ' \ ' 1/-' -.f) \... : \' '.. "'... }.'"\ "'....,\. \.) \'!fj!/.1 \ ,...,.. - '\.,. C o4> l t l. ft, - Figue 1. Field Equipment Setup fo a Typical WM Tuck Weighing Opeation

25 . l eceiving data only fom lane 1 o lane 2. data fom bo.th lanes 1 and 2. t must be used to collect 3. Stain gage tansduces clamped to the bottom flanges of the gides of the weigh span. The stain gage tansduces used thoughout this investigation wee povided by FHWA (Aticle 3.2) and ae clamp-on devi.ces developed by Case Westen Reseve Univesity duing a pile eseach poject. (l 7 ) Small electical esistance stain gages ae attached at fou stess concentation points of the doughnut shaped aluminum tansduce. The gages ae connected in a full bidge. Each tansduce is identified and its calibation value ecoded. The tansduce is easily clamped to the bottom flange of a. steel gide o a pestessed concete gide. Tansduce installations ae shown in' Chapte 4. The gage length is 3 in. (7.62 em.). 4. An instumentation van located beneath the weigh span which houses the weigh-in-motion system consisting of: 1) MNC 11/03 system with minicompute (PDP 11) manufactued by Digital Equipment Copoation (DEC); 2) MNC laboatoy modules equied fo this application which include two hadwae clocks, an analog to digital convete and a digital input device; 3) Dual floppy disk dive fo softwae and data stoage; 4) a signal conditioning cente to collect, condition and amplify the stain signals and to condition the keypad and tapeswitch signals though a debounce cicuit,.and 5) a monito (CRT) to display axle weights, axle spacing, goss vehicle weight and vehicle speed as the data is pocessed in the field. Data is acquied by the MNC system fom thee souces: 1) analog signals fom the stain tansduces; 2) "digital" data fom the tape switches and 3) "digital" signals fom the optional keypad. As a vehicle appoaches the weigh span the appopiate vehicle categoy (box, flat, auto caie, etc.) may be input via the keypad if the keypad option is desied. The system then opeates automatically without futhe input fom the keypad opeato. Wnen the steeing axle aives at the fist tape switch, which is located appoximately 7 feet (2.13 m) befoe the beginning of the weigh span, the compute begins acquiing stain data fom the stain tansduces. The stain data is acquied at the ate of 40 to 80 samples pe second as selected byhe opeato duing the input of the site -19-

26 paametes when loading the data acqisition pogam. The second tape switch is set pecisely 6 feet (1. 83 m) fom the fist tape switch (appoximately 1 foot (0.305 m) befoe the beginning of the weigh span). The MNC system checks the tape switches seveal thousand times pe second fo axle pulses. Wheneve a pulse is detected fom eithe tape switch the clock is ead and the time (timestamp) is stoed. The pecise distance between tape switches can be changed at the beginning of the data acquisition pogam. All axles of the vehicle have been eceived when one of the following two constaits have been met: 1) a limitation of 37 feet (11.28 m) between any two consecutive axles, and/o, 2) a limitation of 65 feet ( m) between the fist and the last axle. These distances ae changed to equivalent time constaints by dividing by the vehicle velocity. The velocity is obtained fom the aival times of the fist axle on each tape switch and the distance between tape switches Axle spacing is obtained in a simila manne. These constaints can be easily changed at the stat of the data acquisition pogam. Once the last axle of the vehicle has been timestamped, the pogam classifies the vehicle as a ca o a tuck based on the numbe of axles and the peak stain value duing the cossing of the weigh span. A ca is abitaily defined as any.two axle vehicle with an axle spacing less than 12.1 feet (3.69 m) o any vehicle causing a peak gide stain less than a peset value. The peset stain level is site dependent and on the ode of 10 micostain. The pupose of this constaint is to pevent a ca pulling a taile to be classified as a tuck. These constaints ae also easily changed at the stat of the data acquisition pogam. f a vehicle is classified as a ca, stain sampling is discontinued. Howeve, the ca velocity is stoed in a sepaate file which can be used fo velocity statistics if desied. f the vehicle is classified as a tuck, stain acquisition is continued fo a pedetemined length of time. At the end of this time velocity and axle spacing ae then displayed on the CRT and.the stain data, tape switch activation times, and site infomation ae ecoded on a floppy disk. The ecoding pocess is pogammed to allow the compute to pefom -20-

27 .. ' othe on-site tasks (at the opeato's option) such as detemining axle weights and goss vehicle weights and simultaneously displaying this infomation on the CRT. The length of time that stains ae acquied is pedetemined at the beginning of the pogam by designating a "span length". This length is not necessaily the length of the weigh span o the bidge length. designated "span length" is conveted to time by dividing by tuck speed. Stain acquisition time will be longe fo slowe moving tucks and shote fo fast moving tucks. The The "span length" selected is a function of the sampling ate and the disk space (buffe length) pe tuck weighing event. The FHWA WM system is designed to stoe 400 tuck weighing events (all stain ecods obtained duing the weighing of one tuck) pe floppy disk. Each floppy disk has a capacity of about 0.5 megabytes. Fo each tuck weighing event 'the buffe length will accommodate up to 480 stain data ecods. a floppy disk fo stoing pocessed data. Additional file space is povided on The weigh-in-motion concept is an "invese" type poblem in that the bending moment is measued (input fom the stain tansduces), but the live loads causing this moment must be calculated. Since data ae ecoded continuously duing tuck passage, the axles ae "weighed" many times. axle weights ae found by minimizing the least squaes diffeence between the measued stains and the values calculated by the data acquisition pogam fom the vehicle dimensions and the influence line fo the weigh span (simple span) o bidge (continuous spans). The influence line can be calculated using a suitable stuctual analysis pogam o detemined in the field using a calibation tuck with known axle weights and spacing. The calibation tuck can tavel ove the bidge at nomal highway speed a sufficient numbe of times to ensue a easonably accuate estimate of the influence line. Futhe details on the design, desciption and opeation of the FHWA WM system ae.contained in Refs. 17, 19, 20, 46 and WM+RESPONSE System Design Paametes On Octobe 17, 1983 M. Haold Bosch, FHWA Contacting Office's Technical Repesentative (COTR) deliveed one FHWA WM system to Fitz -21- The

28 ' Engineeing Laboatoy, Lehigh Univesity. n the appoximately nine months that followed the Lehigh eseach team became familia with the system hadwae and softwae limitations and with the system opeation. n July 1984 the WM system was used to weigh 247 tucks cossing the Tilghman St. bidge on Route 309 west of Allentown, PA. n Septembe and Octobe of 1984 a peliminay WM+RESPONSE system design was tested by weighing 329 tucks cossing the Batonsville bidge on ntestate 80 nea Batonsville, PA., and simultaneously acquiing and stoing data fom thee stain gages located on the thee inteio gides of one of the bidge spans. (! 6, 24 ) Based on this expeience plus a backgound of ove 15 yeas eseach by Lehigh into the stess histoy esponse of ove 70 bidges in the U.S. and elsewhee, ( 6,ll, 35 ' 49 ) Lehigh poposed (SO) and FHWA ageed to, (Sl) the following system design paametes on.which the.fhwa WM system is to be modified and the pototype WM+RESPONSE system designed, built and used to acquie and evaluate load and esponse data fom fou in-sevice bidges (thee steel and one pestessed concete) in Pennsylvania: 1. A pototype WM+RESPONSE system, not a poduction system, is to be designed and built. Pototype is to mean a system that is complete and capable of obtaining simultaneous load and esponse data consistent with the infomation needs discussed in Chapte 2, but of limited capacity and efficiency (poof of concept idea). Poduction is to mean a system with lage capacity and inceased efficiency which evolves fom the use and testing of the pototype system by othes. 2. The pototype WM+RESPONSE system is to be based on a modification and enhancement of the FHWA WM system deliveed to Lehigh in Octobe, The MNC 11/03 is to be upgaded to a MNC 11/23 since DEC no longe suppots the 11/03. This entails, in pat, binging softwae to the latest vesion of the opeating system and FORTRAN fo the 11/ An integated WM plus RESPONSE system is to be designed so that load and esponse data ae stoed simultaneously on the same mass stoage device (floppy disk) since it is impotant when intepeting both types of data that thee ae no questions egading thei elationship in time.(simultaneous). -22-

29 _. ' 5. Softwae developed fo data eduction and load-esponse evaluation (GVW histogams, stess ange histogams, etc;.) is tobe witten fo pocessing by the WM+RESPONSE system and compatible systems. 6. The WM+RESPONSE system is to be capable of acquiing and stoing up to 16 channls of the simultaneous load and esponse data. Up to 6 of these channels ae dedicated to WM data coming fom the stain tansduces clamped to the main gides of.the weigh span. These channels will employ the existing 6 channel WM stain conditioning cente which is pat of the FHWA WM system. These same 6 channels can povide RESPONSE data fom the stain tansduces used fo the weighing opeation plus additional stain tansduces mounted elsewhee on the bidge, if less than 6 ae used in the weighing opeation. A new 10 channel stain conditioning cente will be povided to simultaneously obtain additional channels of RESPONSE data fom up to 10 stain gages mounted anywhee on the bidge. The stain conditioning centes fo both the WM and RESPONSE data equie continuous manual balancing duing field studies to ensue close to zeo stain at all gages pio to a tuck cossing the bidge. Automatic balancing conditiones ae available but ae not used in this system. Consideation should be given to automatic balancing when designing impovements to the WM+ RESPONSE system. 7. The dual floppy disk dives which.ae pat of the FHWA WM system will be incopoated into the WM+RESPONSE system fo stoing load and esponse data. Although a new highe capacity data stoage device such as magnetic tape o had disk is desiable, neithe of these wee consideed efficient no pactical fo use with the pototype system. Pevious expeience in using magnetic tape stoage duing the Lehigh stess histoy stoies indicated that it could not be efficiently used with the WM+RESPONSE system. Use of had disks in field opeations whee the disk dives would be handled oughly and subjected to dusty conditions is not consideed pactical. Howeve, both of these options should be e-evaluated based on the state-of-the-at when designingimpovements to the WM+RESPONSE system. 8. The FHWA WM system is designed to stoe 400 tuck weighing events pe floppy disk, each event consisting of 480 stain data ecods as explained in At Also explained was the fact that to obtain easonably accuate axle weights data acquisition may teminate befoe o afte the -23-

30 .,... tuck cosses the weigh span. The design paametes fo the WM+RESPONSE system, howeve' ae somewhat diffeent. The buffe length must be inceased to accommodate an incease in the numbe of data channels fom 6 to 16. n addition, to obtain a complete ecod of esponse fo a point on the bidge the tuck must not only coss the weigh span but also the esponse spans (if diffeent fom the weigh span) and sampling should continue fo a sufficient time to allow esidual vibations of the weigh. and esponse spans to dissipate afte the tuck has passed. The WM+ RESPONSE system was theefoe designed to achieve a compomise between stoing as many tuck weight plus esponse events pe floppy disk and accommodating as long a span o bidge as possible. The system was finally designed to stoe 110 tuck weight plus esponse events pe floppy disk. A buffe length of 2,000 stain data ecods was also selected. At a sampling ate of 40 samples pe second pe channel, a tuck speed of 55 mph (88 kph) and allowing one second fo esidual vibations to dissipate, a maximum bidge length of about 170 feet (51.8m) can be accommodated. Fo example, one simple span up to 170 feet (51.8m) can be used to obtain both weight and esponse data. Two consecutive simple spans with a total length up to 170 feet (51.8m) can be used with one span poviding weight data and both spans poviding esponse data. A seies of continuous spans o a combination of simple and continuous spans with a total length up to 170 feet (51.8m) can also be used. n this case, one span will be used fo weight data, while esponse data can be obtained fom all spans. 9. The WM+RESPONSE system is capable of obtaining simultaneous load plus esponse data fom moe than 16 gages. While tuck weight data is being obtained fom the weigh span the emaitl.ing esponse channels can be changed peiodically to othe goups of gages. n this way simultaneous tuck weight plus bidge esponse infomation can be obtained fom a lage numbe of locations on the bidge. -24-

31 3.3 Modification of FHWA WM System To achieve the pototype WM+RESPONSE system capabilities descibed in At. 3.2 the FHWA WM hadwae system deliveed to Lehigh in Octobe 1983 was modified extensively. The components needed to make this modification ae listed in Table 1. Also shown in the table ae the additional capabilities achieved with each component and the easons fo selecting each component. Additional softwae is descibed in the Softwae Refeence Manual, Ref WM+RESPONSE System DocUmentation 1. WM+RESPONSE System Oveview (Refeence 25) This document is intended fo administative pesonnel and plannes fom FHWA and State Depatments of Tanspotation. t contains a bief synopsis of what the WM+RESPONSE System is and what it can be used fo. 2. WM+RESPONSE Taining Guide (Refeence 26) This document is intended fo those technicians who need an intoductoy guide on how to opeate the WM+REPONSE System. t contains detailed desciptions, including numeous pictues, on the vaious phase of opeation of the WM+RESPONSE System. 3. WM+RESPONSE System Use's Guide (Refeence 27) This document is intended fo technical pesonnel who need infomation on how to opeate the WM+RESPONSE System. 4. WM+RESPONSE Hadwae Refeence Manual (Refeence 28) This document is intended to povide technical pesonnel with the chaacteistics and basic infomation on the use of all equipment (hadwae) associated with the WM+RESPONSE System. 5. WM+RESPONSE Softwae Refeence Manual (Refeence 29) This document is intended to povide technical pesonnel with the details on how to execute, opeate, and modify the softwae which was developed at Lehigh Univesity fo the WM+RESPONSE System. 6. WM+RESPONSE Appendices (Refeence 30) This document is intended to povide infomation on field tips and notes fom the expeiences of the Lehigh Univesity and FHWA eseaches. -25-

32 B. c. Component A. CPU 1. Memoy Boad-DEC (MSV-11-LK) 2. 11/23 CPU and Memoy Management- DEC (KDF-11-AA) 3. Opeating System, Vesion 5.1-DEC (QJ018-HX) MASS STORAGE 1. Two new floppy disc dives-dec 2. New Cicuit Boads-DEC HARDCOPY DEVCE 1. Potable Gaphics Pinte-DEC (LA-50) D. TERMNAL/CRT E. 1. Gaphics CRT-DEC (VT-125} SGNAL CONDTONERS 1. Vishay Ten Channels (No. 2120) Table 1 - Modifications to FHWA WM System Addit.ional Capabilities 256 kbytes Upgade to MNC - 11/23 System Cuent OS fo 11/23 Retun to functional opeating state Needed eplacement Local hadcopy of tabula o gaphical data fom CRT Gaphics capabilities not available on VT additional channels fo data acquisition -26- Reasons nceased memoy fo data pocessing nceased efficiency and thoughput Pesent vesions of OS fo WM no longe suppoted by DEC WM system failue in Mach, Had disc technology not suitable fo field conditions WM System failue in May, 1984 Compatible with DEC, VT-125 CRT Upgades VT-100 to VT-125. Pemits gaphical displays on CRT Compatible with pesent system. ncludes powe supply and cabinet

33 4. FELD STUDY BRDGES 4.1 Bidge Selection Citeia Pio to Mach 1985, the Pennsylvania Depatment of Tanspotation (PADOT) Distict 5-0 was askedbylehigh to povide a listing of steel and concete bidges having potential fo the field study togethe with maps showing thei locations. This quest poduced a listing of ove 100 bidges, all within Distict 5-0. This list was educed to less than 50 steel and concete bidges located on outes having a significant ADTT (Aveage Daily Tuck Taffic). The objective was to obtain data fom a minimum of about 3,000 to 4,000 tucks cossing each field study bidge within a..5 day (24 hous pe day) data acquisition peiod (600 to 800 ADTT). Between Mach and July 1985 site inspections wee made at about 30 bidges. All ae within 100 miles (160 km) of Lehigh Univesity; 26 ae within 50 miles (80 km). Of these, 4 bidges (3 steel and one pestessed concete) wee selected fo the field study and included in the wok plan pesented to and vebally appoved by M. Haold Boch, COTR, FHWA < 52 ). The following citeia wee used to select the fou bidges which ae descibed in Aticle 4.2: 1. The fou bidges ae to be located within PADOT Distict 5-0. Most of the ove 70 bidges on which stess histoy studies wee conducted by Lehigh ove the past 15 yeas wee located in Distict 5-0. Duing this time a high degee of coopeation was developed between Lehigh and Distict 5-0 enginees. This coopeation was consideed a desiable asset in conducting the field studies. 2. Of all the bidges inspected, the fou most suitable bidges neaest to Lehigh Univesity ae to be selected. Not only ae financial esouces conseved, but pevious stess histoy study expeience has shown that field studies ae moe efficiently oganized and executed if tavel time to and fom the bidges is kept to a minimum. Within the Univesity envionment much of the field study wok is pefomed by gaduate students and these students have class schedules to meet as well as othe eseach obligations thoughout the yea. -27-

34 3. The field studies ae to be conducted between May and Octobe, pefeably duing June, July and August. The ai tempeatues should be highe than 40 to 50 degees Fahenheit (4.4 to 10 degees Celcius) and the elative humidity faily low so that stain gaging of the bidges can be accomplishedwithout difficulty. Also gaduate student help is moe eadily available outside of the egula academic semeste (late August though mid-may). 4. Right o skewed bidges ae acceptable. Although ight bidges esu 1 t 1n. moe accuate ax. 1 e we1g. "h ts,.. (l9) i t 1s. d es i a bl e to 1nc. 1 u d e bo'th ight and skewed bidges in the esponse data About to 1 mile (0.8 to 1.6 km) of easonably level appoach is equied fo nealy constant. taffic speed ove the weigh span so that accuate axle weight and spacing can be obtained. 6. About mile (0.8 km) site distance is equied fo taffic contol and pesonnel safety duing installation of the tape switches on the bidge appoach at the stat of the opeation as well as eplacement of tape switches duing the opeation and emoval of tape switches at completion. 7. Smooth oadway suface in the vicinity of the tape switches is equied to avoid wheels bouncing and skipping ove the tape switches. 8. Relatively smooth deck on the weigh span is needed to avoid significant impact loading which would affect the WM data. (This citeion conflicts with the desiability fo a ough deck which would enhance the RESPONSE data). 9. Steel gide supestuctues ae to include some inteesting welded, bolted o iveted details and stiffeneso diaphagms which might yield potentially high dispiacement induced stess anges. 10. Fo concete bidges, pestessed concete -gides o einfoced concete T-gidets ae pefeed. Othe configuations, such as slab bidges o box gides would make it difficult o impossible with the cuent WM system instumentation to obtain weight data. 11. Accessibility of the gides fom below the bidge is equied, within a easonable height. nstallation of the stain gage tansduces and stain gages is moe difficult if the bidge is quite high o ove wate. -28-

35 12. A easonably low level of taffic on the oadway below the bidge and good site distances ae needed fo pesonnel safety duing installation of the stain gage tansduces and stain gages. 13. A suitable off-oadway location fo the instuments van below the bidge is equied fo pesonnel safety especially duing night time opeations. 14. Availability of an electical powe souce is equied, located within about 400 feet (122.metes) of the instuments van. Expeience obtained at the Tilghman Steet and BatonSville bidges indicated that fo continuous week log data collection the potable powe supply esulted in too many powe inteuptions (to add gasoline and oil and to change oil) and was faily noisy. 15. n confomance with the WM+RESPONSE system design paametes, specifically item 16, Aticle 3.2, the appopiate span o bidge length is limited to a maximum of 170 feet (51.8 metes). 16. Since a maximum of 6 stain gage tansduces ae available fo tuck weight data, the weigh span supestuctue is limited to a maximum of 6 inteio gides. 4.2 Desciption and nstumentation EB Route 22 ove 19th St. 1. Bidge: East bound (EB) two lanes of PA Route 22 (Pat of ntestate 78) cossing ove 19th Steet in Allentown, PA. Two lane bidge with fou, ight, simple, steel gide spans: Span 1: 45'-10 (13.97 m) Span 2: 84'-10 (25.61 m) Span 3: 125'-10 (38.11 m) Span 4: 35'-10 (10.92 m) 2. Weigh Span: Span 2 3. Response Span: Span 2 4. Span 2 Supestuctue: Figue 2 shows a patial coss section though the fascia and fist inteio gides. Span 2 consists of 5 multiple, iveted built-up steel plate gides, with a newly constucted 8 in. (21.59 em) composite concete deck. Gides ae spaced at 8'-0 (2.44 m). The deck width is 32'-6 (9.91 m) cub-to-cub. -29-

36 5. nstumentation: Figue 3 shows.the locations of the stain gage tansduces and stain gages on span 2 of the EB bide. All stain gages ae in. (0.64 em) electical esistance gages. n the figue, the tansduces ae numbeed 1 though 6. Weight and esponse data wee obtained fom tansduces 1, 2 and 3. Tansduces 4, 5 and 6 wee used fo esponse data. The stain gages, which ae used fa esponse data, ae numbeed 7 though 16. The tansduces and stain gages in Coss Sections 1 and 2 ae mounted on the undeside of the bottom flanges and ae positioned 1 in. (3.81 em) fom the edge ofthe plate. The locations of Sections 1 and 2 wee established so that the tansduces and stain gages would fall midway between the outside line of. ivets which ae at a 6 in. (15.24 em) spacing. Sections 1 and 2 wee also located within the egion of maximum bending moments poduced by most tucks. All tansduces and stain gages on the gides ae oiented to measue stains in the longitudinal diection of the gides. Stain gages on the diaphagm membes ae oiented to measue stain in the diection of the membes and ae located midway between connections. 6. ADTT: The estimated aveage daily tuck taffic (ADTT) is 2,000 to 3,000 on peak days. PADOT also estimates 40,000 to 60,000 aveage daily taffic (ADT) with possibly 80,000 ADT on peak days. Due to econstuction of Route 22, 10 miles (16 km) east of the bidge duing the field study, the ADTT was expected to be somewhat lowe than the PADOT estimate. 7. Data Sample: Weight and esponse data wee obtained fom 4,680 tucks cossing the span in both lanes duing the 5 day peiod, June 18 though 22, Bidge Photos: Figues 4 and 5 ae aeial views of Route 22 looking east. The EB bidge (and WB bidge -Aticle 4.2.2) ae situated at the fa (distant) end of the segment of Route 22 shown in the figues. The City of Allentown is mostly unde the aicaft wing. The City of Bethlehem is in the distance mostly to the left of the wing. The Allentown-Bethlehem-Easton (ABE) aipot is just beyond the fa end of the segment of Route 22 shown in Fig. 4. (ABE ai taffic contolles would not pemit low level aeial photogaphy close to the bidge since it is located on the appoach to and about 4 miles (6.4 km) fom Runway 6). -30-

37 Figues 6 though 9 show vaious views of the EB bidge. The appoach to the bidge is shown in Fig. 6. Figue 7 shows a view looking east ove the bidge With span 1 in the foegound. The tuck shown in Fig. 7 is in lane 2 and about to ente s.pan 3. Figue 8 shows a tuck cossing the EB bidge in lane 1; the ea of the tuck is on span 1 and the font is on span 2. Figtie 9shows the tape switchesin lanes 1 and 2 of span 1. The joint between spans 1 and 2 is visible to the ight of the figue. 9. Additional Remaks: n addition to the citeia listed in Aticle 4.1, additional factos involved in the selection of the EB bidge ae as follows: a) Route 22 has a elatively high ADTT. A age pecentage of the heavie tucks ae tavelling to New Yok City (fom New Yok City fo the WB Bidge -Aticle 4.2.2) located about 90 miles east of the bidge. b) The weight and esponse data can be compaed with the adjacent WB bidge (Aticle 4.2.2) whee the significant vaiable is expected to be span length. c) The oiginal EB bidge was constucted in 1951 and had a noncomposite 8 in. (20.32 em) concete deck. A new 8 in. (21.59 em) composite concete deck was constucted in No modifications wee made to the steel gides. The esponse behavio of the fascia gides is of inteest because of the new design povisions fo exteio gides intoduced with the 1957 AASHTO Specification, 7th Edition. -31-

38 x 5tae.'s TaB 2 L 6 x 6 x 3t4 T a e L 3 Jt2 x 3 x 3ta w N 54 x 3ta Web -+-1 nteio Gide Fascia Gide : L Fig. 2 - Patial Coss Section Though Fascia and Fist nteio Gides N.

39 1. t TRAFFC DRECTON 1 ft m 6' ' ' ' Fig. 3 :... Locations of Tansduces and Stain Gages -33-

40 Fig. 4 -Aeial View of Route 22 Looking East Fig. 5 - Aeial View of Route 22 Looking ENE -34- J

41 Fig. 6 - Appoach to the EB Bidge Fig. 7 - Looking East Ove the EB Bidge -35-

42 . 1- Fig. 8 - Tuck Cossing Spans 1 and 2 in Lane 1 Fig. 9- Tape Switches. in Lanes 1 and 2 of Span 1-36-

43 4.2.2 WB Route 22 ove 19th St. 1. Bidge: West Bound (WB) two lanes of PA Route 22 (Pat of ntestate 78) cossing ove 19th Steet in Allentown, PA. Two lane bidge with fou, ight, simple, steel gide spans: Span 1: 35'-10 (10.92 m) Span 2: 125'-10 (38.11 m) Span 3: 84'-10 (25.61 m) Span 4: 45'-10 (13.97 m) (Note: The EB (Aticle 4.2.1) and WB bidges ae paallel, adjacent stuctues. Fo puposes of this epot, span 1 of each bidge is the fist span encounteed by a tuck cossing the bidge). 2. Weigh Span: Span 2 3. Response Span: Span 2 4. Span 2 Supestuctue: Figue 10 shows a patial coss section though the fascia and fist ineio gides. Span 2 consists of 5 multiple, iveted, built-up, steel plate gides, with a newly constucted 8 in. (21.59 em) composite concete_deck. Gides ae spaced at 8'-0 (2.44 m). The deck width is 32'-6 (9.91 m) cub-to-cub. 5. nstumentation: Figue 11 shows the locations of the stain gage tansduces and stain gages on span 2 of the WB bidge. All stain gages ae 1/4 in. (0.64 em) electical esistance gages. n the figue the tansduces ae numbeed 1 though 6. Weight and esponse data wee obtained fom tansduces 1, 2 and 3. Tansduces 4, 5 and 6 wee used fo esponse data. The stain gages, which ae used fo esponse data, ae numbeed 7 though 16. The tansduces and stain gages in Sections 1 and 3 ae mounted on the undeside of the bottom flanges and ae positioned 1 in. (3.81 em) fom the edge of the plate. The locations of Sections 1 and 3 wee established so that the tansduces and stain gages would fall midway between the outside line of ivets which ae at a 6 in. (15.24 em) spacing. Sections 1 and 3 ae also located within the egion of maximum bending moments poduced by most tucks. All tansduces and stain gages on the gides ae oiented to measue stains in the longitudinal diection of the gides. Stain gages on the diaphagm membes ae oiented to measue stain in the diection of the membes and ae located midway between connections. ' -37-

44 6. ADTT: (Same as fo the EB bidge - Aticle 4.2.1) 7. Data Sample: Weight and esponse data wea obt"!,ined fom 7,112 tuckscossing the span in bothlanes duing the 6 day peiod, June 24 though 29, Bidge Photos: Figues 12 though 15 show vaious views of the WB bidge. (See Figues 4 and 5 fo aeial views ofroute 22 on which the WB bidge is located). The appoach to the bidge is shown in Fig. 12. Figue 13.shows a view looking west ove the bidge with span 1 in the foegound. The tuck in lane 1 is on span 2. The figue also shows the tape switches in lanes 1 and 2 of span 2. Figue 14 shows a tuck in lane 1 cossing span 2. Figue 15 shows a view looking west duing the instumentation of span 2, which employed a PADOT lift tuck, the platfom of which is shown in the figue. 9. Additional Remaks: (Same as fo the EB Bidge - Aticle 4.2.1) -38-

45 L 8 X 6 x 3/4 T l.-; tl , :' 3 1'/ 2 " L32x3x 3/a ', ' w \0 nteio Gide 90 x 112 Web 1t. 90x 2 Web t Fascia Gide L 3 2 X 3 X 8, ',. v == N Fig._ 10 - Patial Cos Section Though Fascia and Fist nteio Gides

46 - TRAFFC DRECTON 3'-6" 7'-6" " 62'-6" 125',-o" c=fl--- f Section (D---(D, 12 Section ---(g) 8, ft. = m 31!2 14 Section Fig Locations of Tansduces and Stain Gages -40-

47 Fig Appoach to the WB Bidge Fig Looking West Ove the WB Bidge -41-

48 Fig Tuck Cossing WB Bidge in Lane 1 Fig 15 - nstumentation of Span 2 fom PADOT Lift Tuck -42-

49 4.2.3 NB Route 33 Ove Van Buen Road 1. Bidge: Noth Bound (NB) two lanes of PA Route 33 ove Van Buen Road, located one mile (1.6 km) noth of PA Route 248 and about 10 miles (16 km) NE of Bethlehem, PA. Two lane bidge with thee, skew, simple, steel gide spans: Span 1: 39'-7 5/8 (12.08 m) t 06" skew Span 2: 108'-3 (32.99 m) 53 29t 06" skew Span 3: 39'-7 5/8 (12.08 m) 53 29' 06" skew 2. Weigh Span: Span 1 3. Response Spans: Spans 1 and 2 4. Span 1 Supestuctue: Figue 16 show5 a patial plan of the supestuctue containing the span 1 gides.. Span 1 consists of 6, multiple, hot olled W33 x 130 steel gides with an 8 in. (21.59 em) non-composite concete deck. Gide spacing is 7'-4 (2.24 m). The deck width is 40'-0" (12.19 m) cub-to-cub. 5. Span 2 Supestuctue: Figue 16 also shows the span 2 gides and a patial coss section though the fascia and fist two inteio gides. Span 2 consists of6, multiple, welded, steelplate gides with an 8 in. (21.59 em) composite concete deck. Gide spacing is 7'-4 (2.24 m). The deck width is 40'-0 (12.19 m) cub-to-cub. 6. nstumentation: Figue 16 also shows the locations of the stain gage tansduces and stain gages on Spans 1 and 2. All stain gages ae 1/4 in. (0.64 em) electical esistance gages. n the figue the tansduces ae numbeed 1 though 6. Weight and esponse data wee obtained fom tansduces 1 though 4. Tansduces 5 and 6 wee used fo esponse data. The stain gages, which ae used fo esponse data, ae numbeed 7 though 16. The tansduces on span 1 ae mounted on the bottom of the bottom flanges of the steel gides, at mid-span, and oiented to measue stains in the longitudinal diection of the gides. Stain page 7 is mounted below the web and 1/2 in. (1.27 em) fom the end of the bevelled flange splice as shown in the figue and measues longitudinal stain in the flange. Stain gages 8 and 11 ae mounted to measue vetical stains (membane stain) on the webs of the fascia and fist inteio gide. The gages ae located just below the end of a fillet weld joining the diaphagm connection plate (tansvese web stiffene) to the web, which -43-

50 . teminates at the cope. These stain gages ae designed to measue displacement induced stains which often occu in these locations when the connection plate is not. welded t? the bottom flange. Stain gages 9, 10, 12 and 13 ae mounted on' the diaphagm membe and ae oiented to measue stain in the diection'of the membe They ae placed midway between connections. Stain gages 14, 15 and 16 ae located on the undeside of the bottom flanges of. the plate gides, diectly unde the web, and oiented to measue stains in the lonitudinal diection of the gides. These thee gages ae located 2'-4 (0.71 m) fom midspan which is the maximum moment location fo an HS 20 (MS 18) tuck. 7. ADTT: PADOT estimated ADTT is 1, Data Sample: Weight and esponse data wee obtained fom 3,626 tucks cossing spans 1 and 2 in both lanes duing the 6 day peiod July 22 though 27, Bidge Photos: Figues 17 and 18 ae aeial views of the PA Route 33 which show the NB and SB bidges cossing Van Buen Road. Figue 17 is a view looking SW towads Bethlehem, PA (a out 10 miles (16 km) away). The NB bidge is the left most bidge of the pai of bidges situated to the left of the lage buildings. The NB bidge is in the foegound of Fig. 18 which is looking about NNW. Van Buen Road, situated noth-south, passes unde the bidge. The instuments van can be seen in Fig. 18 paked unde the left end of span 2 (see also Fig. 21). Figues 19 though 23 show vaious views of the NB bidge. Figue 19 shows the appoach to the NB bidge. Figu:e 20 a view looking NE ove the bidge with span 1 in the foegound. The tacto of the tuck in lane 2 is on span 1. The figue also shows the skew angle and the tape switches on the appoach pavement. The tape switches ae pependicula to the bidge centeline. Span 2 and the instuments van which is paked off Van Buen Road ae shown in Fig. 21. Figue 22 is a view looking NE fom the abutment end of span 1. Span 1 is in the foegound; span 2 is beyond the pie. Anothe view of the tape switches in lanes 1 and 2 of pavement appoach to Span 1 is shown in Fig. 23. The data acquisition set-up in the instuments van is shown in Fig. 24. Pat of the MNC 11/23 system, containing the PDP 11 compute and dual dive, can be seen in the lowe ight hand cone of the figue. The VT-125 gaphics CRT and keyboad ae to the left of the -44-

51 MNC 11/23. To the left of the VT-125 ae the two signal conditioning units. The lowe unit (next to M. L. Y. Lai's hand) contains the 6 Vishay signal conditiones which ae connected to the 6 stain gage tansduces mounted on span 1. The uppe unit contains the 10 Vishay signal conditiones which ae connected to the 10 stain gages mounted on span Additional Remaks: n addition to the citeia listed in Aticle 4.1, additional factos involved in the selection of the NB bidge ove Van Buen Road ae as follows: a) This bidge is the neaest suitable welded steel gide bidge to Lehigh Univesity, meeting the citeia of Aticle 4.1 including the equiement fo a easonably high ADTT oute tavelled by a significant pecentage of heavy tucks. Route 33 is one of the majo connecting links between ntestates 78 and 80 and caies significant tuck taffic to and fom New Yok City. b) Compaison of esponse data fom both olled gide and plate gide spans is achieved. c) Weight and esponse data obtained fom the NB bidge ove Van Buen Road can be compaed with data obtained fom the NB bidge ove State Pak Road (Aticle 4.2.4) both of which ae located on the NB lanes of PA Route 33, whee the significant vaiable is bidge gide constuction (steel vesus pestessed concete). d) The bidge was constucted in

52 a- 1 Bg. Taffic Diection,,, Span 5 do 7 J5/t61E.g. 2qJ61E.g. Elevation F 9,10.12,13 Typ. Detail Span 2 Span 1 ft m 39' '-Y2" 6 W38x " x Y2" 1!. Gide 4 do 35' Faming Plan - ' Nothbound 7',-4 11 Fig Patial Plan and Coss Section of Supestuctue Showing Locations of Tansduces and Stain Gages -46- do Section CD-Q) 7'-4,.. _L Typ. Detail (Ga. Simila) 81 3'-8" typ. 'tyr X Y2 Web 1!.

53 Fig Fig Aeial View of Route 33 Looking South West Aeial View of Bidges Ove Van Buen Road -47-

54 a Fig Fig Appoach to the NB Bidge Looking Noth East Ove the NB Bidge -48-

55 ,. Fig nstuments Van Paked Unde Span 2 Fig ====== ====== --===:::J --- l t.. -- 'j1-j,;.- Looking Noth East Fom Span 1 Abutment

56 '1 a- l ' Fig Tape Switches on Pavement Appoach to Span 1 Fig Da ta Acquisition Set-Up in nstuments Van - 50-

57 ' ' a, NB Route 33 Ove State Pak Road 1. Bidge: Noth Bound (NB) two lanes of PA Route 33 ove Van Buen Road, located two miles (3.2 km) noth of the Belfast exit on Route 33 and about 4 miles (6.4 km) noth of the NB Route 33 bidge ove Van Buen Road (Aticle 4.2.3). Two lane bidge with thee, skew, simple, pestessed concete!-gide spans: Span 1: 28'-0 (8.53 m) 48 46' 55" skew Span 2: 66'-3 (20.21 m) 48 46' 55" skew Span 3: 28'-0 ( 8.53 m) 48 46' 55" skew 2. Weigh SEan: Span 2 3. Response Spans: Spans 2 and 3 4. span 2 Su12estuctue - Figue 25 shows a patial plan of the supestuctue and coss section of the span 2 gides. Span 2 consists of 6, multiple; pestessed!-gides with an 8 in. (20.32 em) composite concete deck. The pestessed gides ae PADOT Type 24"/45" (0.61 m/1.14 m)f5 3 ) Gide spacing is 7'-4 (2.24 m). The deck width is 40'-0 (12.19 m) cubto-cub. 5. Span 3 Supestuctue - Figue 25 also shows the span 3 gides. Span 3 consists of 6, multiple, pestessed!-gides with an 8 in. (20.32 em) composite concete deck. 20"/30" (0.51 m/0. 76 m). < 53 ) width is 40'-0 (12.19 m) cub-to-cub. The pestessed gides ae PADOT Type Gide spacing is 7'-4 (2.24 m). The deck 6. nstumentation: Figue 25 also shows the locations of the stain gage tansduces and stain gages on spans 2 and 3. 'All stain gages ae 5 in. (12.70 em) electical esistance gages. n the figue the tansduces ae numbeed 1 though 6. Weight and esponse data wee obtained fom tansduces 1 though 4 (on span 2). Tansduces 5 and 6 (on span 3) wee used fo esponse data. esponse data, ae numbeed 7 though 16. The stain gages, which ae used fo The tansduces on spans 2 and 3 ae mounted on the sides of the bottom flanges of the pestessed!-gides, about 2 in. (5.08 em) fom the bottom suface of the gide, and at mid-span. All tansduces ae oiented to measue stains in the longitudinal diection of the gides. Stain gages 7 and 8 and 13 though 16 ae mounted on the undeside of the pestessed gides midway between the two edges. They ae also oiented to measue stains in the -51-

58 1/ a t: longitudinal diection of the gides. The emaining 4 stain gages numbeed 9 th:t: 9ugh 12 ae mounted hoizontally on a diaphagm in span 2 as shown in Fig ADTT: PADOT estimated ADTT is 1, Data Sample: Weight and esponse data wee obtained fom 3,984 tucks cossing spans 2 and 3 in both lanes duing the 8 day peiod, August 12 though 19, Bidge Photos: Figues 26 and 27 ae aeal views of PA Route 33 which showthenb and SBbidges cossing State Pak Road. Figue 26 is a view looking noth. The NB bidge ove State Pak Road is located.. about midway between the two bends in the highway which can be seen nea the top of the figue. shows State Pak Road passing unde the bidge. Figue 27 is a view looking appoximately east and fathe east of the two bidges shown in the figue. vaious views of the NB bidge. The NB bidge is the Figues 28 to 35 show The appoach to the bidge is shown in Fig. 28. The tacto of the tuck shown in lane 1 is mostly on span 3. The ea axles of the taile ae on_span 2. tuck in lane 1 cossing spans 2 and 3. Figue 29 also shows a The tape switches ae mounted in lanes 1 and 2 of span 1 and ae visible in the figue at the fa end of span 1 (span in the foegound). lift tuck is shown in Fig. 30. nstumentation of span 2 fom the PADOT Span 3 is to the ight. Figue 31 shows the long clamps that ae used to mount a tansduce on the side of a pe-. stessed -gide. A tansduce and the two clamps holding it to the side of a pestessed -gide ae shown in Fig. 32. Fo installation on pestessed gides, long adjustable clamps ae used to accommodate bottom flange widths up to 27 in. (0.69 m). Fo steel gides small 2 in. (3.08 em) clamps ae used which span the flange thickness. n this case the tansduce can be mounted on the top o bottom suface of a steel flange. Figue 33 shows the tansduces and stain gages on span 2. The neaest tansduce is tansduce numbe 1 (Fig. 25). the gide at the top of the figue is gage numbe 8. diaphagm is between gage 8 and tansduce 1. stain gages 13 and 14 on span 3 ae shown in Fig. 34. gages on the diaphagm ae shown in Fig The stain gage on The instumented Tansduce numbe 5 and The fou stain

59 a ' ' '.,, 10. Additional Remaks: n addition to the citeia listed in Aticle 4.1, additional factos involved in the selection of the NB bidge ove State Pak Road ae as follows: a) This bidge is the neaest suitable pestessed concete -gide bidge to Lehigh Univesity, meeting the citeia of Aticle 4.1 including the equiement fo a easonably high ADTT oute tavelled by a significant pecentage of heavy tucks. b) Weight and esponse data obtained fom the Van Buen Road and State Pak"Road bidges can be compaed. c) The bidge was constucted in ' -53-

60 a : ntemediate Diaphagms Span 33'-13/4 11 do Span 2 28'-o" do Ck.Span do Faming Plan -Noth Bound Section CD--<D 1 ft- = m Fig Patial Plan and Coss Section of Supestuctue Showing Locations of Tansduces and Stain Gages -54- <lspan Bg.

61 Fig Fig Aeial View of Route 33 Looking Noth Aeial View of Bidges Ove State Pak Road -55-

62 , - ' ' Fig Fig Appoach to the NB Bidge Looking Noth Ove the NB Bidge =:---

63 1 Fig Fig nstumenting Span 2 Fom PADOT Lift Tuck Method of Clamping Tansduces to the Pestessed Concete - Gides (Span 3) -57-