The characterization of the dynamic interaction between highway bridges and long, multi-trailer heavy vehicles

Meyer, Markus Willem (2022-04)

Thesis (PhD)--Stellenbosch University, 2022.

Thesis

ENGLISH ABSTRACT: Around the world, many countries are experiencing an increase in demand for freight to be transported by road. One solution is to introduce larger heavy vehicles, which are capable of transporting more freight. These vehicles have more trailers, more axles and are longer and heavier than existing heavy vehicle traffic. All these factors have an important influence on the dynamic amplification between the vehicle and bridge. This contribution investigates the dynamic behaviour of long, multi-trailer vehicles, specifically the B-Double vehicles, when crossing short to medium span bridges. The dynamic behaviour of these larger vehicles is compared to the well-known single articulated vehicles which are currently operating in many countries around the world. The effect of axle groups and their spacing on dynamic amplification is explored in depth to support the finding that the time of entry of axle groups on an excited bridge is key to the explanation of dynamic response. The relationship between midspan accelerations and dynamic amplification is introduced and explored extensively for further validation of the findings presented. There is an indication that the commonly accepted inverse relationship between the high static load and observed low dynamic amplification is not generally true when comparing vehicles of different axle configurations. The number of axles, along with inter-axle spacing matching the natural frequency of the bridge, is of substantial relevance to the dynamic response, yielding in some cases higher dynamic amplification of high static loads. It is shown that due to the latter, the significantly heavier vehicles can induce higher dynamic amplification on medium span bridges than some lighter vehicles with different axle configurations. Furthermore, a dynamic load signature is developed which defines the typical dynamic loads induced by B-Double vehicles at midspan for short to medium span bridges. It is shown that the dynamic loads can be defined as a function of the first natural frequency of the bridge and the midspan accelerations. Ultimately, a new method of estimating dynamic amplification factors by implementing a dynamic load signature function in addition to strain and acceleration measurements, is proposed.

AFRIKAANSE OPSOMMING: Regoor die wêreld ervaar lande 'n toename in die vraag om goedere padlangs te vervoer. Een oplossing is om groter swaarvoertuie bekend te stel met ‘n hoër vragkapasiteit. Hierdie voertuie het meer sleepwaens, meer asse en is langer en swaarder as bestaande swaarvoertuigverkeer. Al hierdie faktore het 'n belangrike invloed op die dinamiese versterking tussen die voertuig en die brug. Hierdie bydrae ondersoek die dinamiese gedrag van lang, veelsleepwa-voertuie, spesifiek die “B-Double” voertuie wanneer hulle kort- tot mediumspan-brûe oorsteek. Die dinamiese gedrag van hierdie voertuie word vergelyk met die bekende enkel-geartikuleerde voertuie wat tans in baie lande regoor die wêreld werk. Die effek van asgroepe en hul spasiëring op dinamiese versterking word in diepte ondersoek om die bevinding te ondersteun dat die tyd van toetrede van asgroepe die sleutel is tot die verduideliking van die dinamiese reaksie. Die verband tussen middelspanversnellings en dinamiese versterking word bekendgestel en omvattend ondersoek vir verdere bevestiging van die voorgestelde bevindinge. Daar is 'n aanduiding dat die algemeen aanvaarde omgekeerde verband tussen die hoë statiese las en waargenome lae dinamiese versterking nie oor die algemeen waar is wanneer voertuie met verskillende askonfigurasies vergelyk word nie. Die aantal asse, tesame met tussenaspasiëring wat ooreenstem met die natuurlike frekwensie van die brug is van wesenlike relevansie vir die dinamiese reaksie, wat in sommige gevalle hoër dinamiese versterking van hoë statiese ladings lewer. Daar word getoon dat as gevolg van laasgenoemde, die aansienlik swaarder voertuie hoër dinamiese versterking op mediumspan-brûe kan induseer as sommige ligter voertuie met verskillende as-konfigurasie. Verder word 'n dinamiese laskenmerk ontwikkel wat die tipiese dinamiese vragte definieer wat deur B-Double-voertuie by middelspan vir kort tot mediumspan-brûe veroorsaak word. Daar word getoon dat die dinamiese ladings definieer kan word as 'n funksie van die eerste natuurlike frekwensie van die brug en die middelspanversnellings. Ten slotte word 'n nuwe metode voorgestel om dinamiese versterkingsfaktore te skat deur die dinamiese laskenmerkfunksie bykomend tot vervormings- en versnellingsmetings te implementeer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/124561
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