Influence of number and quality of weigh-in-motion data on evaluation of load effects on bridges : doctoral thesis

Žnidarič, Aleš (author), Turk, Goran (mentor), OBrien, Eugene J. (comentor)

The thesis is dealing with the influence of number and quality of weigh-in-motion (WIM) data to calculate load effects on bridges. Weighing in motion is the only method that provides continuous and unbiased information on traffic loads, but the data contains errors as a result of environmental influences and measurements that can not be constantly monitored. Presented are improvements of bridge WIM technology, which replaces the weighing sensors in the road surface with instrumented bridge superstructures. The system had many advantages, but also shortcomings that prevented its long-term installations. Proposed are a new installation procedure for the sensors that detect axles of the vehicles, a new way of calculating the influence lines, which is based on the responses of crossing vehicles, a method that deals with measurement errors caused by cracks in concrete, and a procedure that takes into account the impact of temperature on the behaviour of bridges. Also shown is the procedure to determine the dynamic loads that the commercial vehicles induce, and their impact on the measurement results. The following chapter elaborates quality control of bridge WIM data. The proposed procedures check and correct typical errors that occur during the measurements, assess quality and reliability of data and significantly shorten the time needed for its verification. Simulation procedures, which are predominantly used for calculating the traffic load effects on bridges, are complex and time intensive. The convolution method, a less demanding procedure appropriate for short to medium-span bridges, was thoroughly investigated. The results were compared with the ones obtained by comprehensive simulations. Convolution method has facilitated the detailed analysis of the impact of quantity and quality of WIM data on calculated moments and shear forces, for simply supported bridges with spans between 5 and 45 meters, which represent the vast majority of all bridges. The size of data samples was varied to investigate its influence on the load effects. Then, various data sources, with respect to quality of data (measured, electronically corrected, visually verified), were examined. The results give clear indications about the required number and quality of WIM data for effective modelling of traffic loads on bridges.

• Language: English
• Keywords: building environment, civil engineering, thesis, bridge, traffic loading, weigh-in-motion, WIM, convolution, 624.21:624.042:656.1:519.29:519.248:(043), measurements, data quality, dynamic loading, freight vehicles, statistical methods
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [IA. Žnidarič]
• Year: 2017
• Number of pages: XXX, 222 str.
• PID: 20.500.12556/RUL-94278
• UDC: 624.21:624.042:656.1:519.29:519.248:(043)
• COBISS.SI-ID: 8109921
• Publication date in RUL: 27.07.2017

Secondary language

• Language: Slovenian
• Title: Vpliv števila in kvalitete podatkov tehtanja vozil med vožnjo na določitev obremenitev mostov : doktorska disertacija

Abstract

V disertaciji je obdelan problem vpliva števila in kvalitete podatkov tehtanja vozil med vožnjo (WIM meritev) na izračun notranjih sil, ki se uporabljajo pri analizi mostov. Tehtanja med vožnjo edina zagotavljajo neprekinjeno in neizkrivljeno sliko o prometnih obremenitvah, vendar podatki vsebujejo napake, ki so posledica vplivov iz okolja ter meritev, ki jih ni mogoče stalno kontrolirati. Predstavljene so izboljšave mostnega sistema WIM, ki, namesto senzorjev v vozišču, za tehtanje uporablja instrumentirano mostno konstrukcijo. Sistem je imel kljub številnim prednostim pomanjkljivosti, ki so preprečevale njegovo uporabo preko daljših obdobij. Predlagan je bil nov način namestitve senzorjev za zaznavanje osi vozil, nov način računanja vplivnic, ki temeljijo na odzivu mostu pod obtežbo vozil, upoštevanje korekcijskih faktorjev zaradi napak, ki so posledica razpok v betonskih konstrukcijah, ter upoštevanje vpliva temperature na obnašanje mostu. Prikazan je tudi način določitve dejanskih dinamičnih obremenitev zaradi tovornih vozil in njihov vpliv na rezultate meritev. V nadaljevanju je prikazan postopek kontrole kvalitete podatkov WIM. Razviti so bili postopki za preverjanje in popravljanje tipičnih napak, ki se pojavijo med meritvami, ter metode, s katerimi je mogoče oceniti kvaliteto in zanesljivost podatkov ter bistveno skrajšati čas za njihovo preverjanje. Postopki simulacije, ki se pretežno uporabljajo za računanje karakterističnih prometnih obremenitev, so kompleksni in časovno zahtevni. Zato smo celovito ovrednotili metodo konvolucije, ki z uporabo enostavnih statističnih metod, na mostovih kratkih in srednjih razpetin, daje povsem primerljive rezultate kot bolj kompleksne simulacije. Rezultate smo verificirani z rezultati detajlne simulacije narejene na podlagi istih podatkov. Metoda konvolucije je omogočila celovito analizo vplivov števila in kvalitete podatkov WIM na izračunane momente in strižne sile za tipske prosto-ležeče razpetine med 5 in 45 metri, ki zajemajo veliko večino vseh realnih mostov. Spreminjali smo količino podatkov in preverjali vpliv velikosti vzorca na izračunane notranje sile. Pri tem smo uporabili različne vire podatkov, od surovih, do elektronsko in vizualno prečiščenih. Rezultati podajajo jasno sliko o potrebnem številu in kvaliteti podatkov WIM za učinkovito modeliranje pričakovanih maksimalnih momentov in prečnih sil na mostovih.

• Keywords: grajeno okolje, gradbeništvo, disertacije, most, prometna obtežba, tehtanje vozil med vožnjo, WIM, meritve, kvaliteta podatkov, konvolucija, dinamična obtežba, tovorna vozila, statistične metode