Short span bridges are commonly used throughout the United States to span small waterways and highway overpasses. New technologies in the civil engineering industry have aided in the creation of many unique designs of these short span highway bridges in efforts to decrease construction cost, decrease maintenance costs, increase efficiency, increase constructability, and increase safety. Three innovative systems, the Integral Abutment Bridge, “Bridge-in-a-Backpack”, and the Folded Plate Girder bridge will be analyzed to study how the bridges behave under various types of loading. Detailed finite element models were created for integral abutment bridges of varying geometry. These models are used to study how the live load distribution transversely across the bridge is effected by varying geometric properties and varying modeling techniques. These models will also be used to determine live load distribution factors for the integral abutment bridges and compare them to current American Association of State Highway and Transportation Officials specifications. The “Bridge-in-a-Backpack” and the Folded Plate Girder bridges were each constructed with a variety of instruments to measure the bridge movements. Readings from these instruments are used to determine the bridge response under various loading conditions. Bridges were analyzed during their construction process, during static live load testing, and during long term seasonal changes. The results from these studies will aid in the refinement of these innovative designs.

Dagens samhälle går mot en livsstil som präglas av möjligheter att göra allt fler hållbara val. För att minska koldioxidavtrycket krävs en fortsatt stabil omställning till förnyelsebara energikällor, i vilken vindkraften har en betydande roll. Det här projektet syftar till att, under statiska förhållanden, studera lagren i vindkraftverkens pitchsystem och deras prestation, att undersöka lastfördelningen mellan rullkropparna i lagren, samt att bestämma kontaktvillkoren mellan ytterring och rullkropp. Genom att anta kvasi-statisk belastning på rotorbladet under en rotation har lagrens lastfördelning beräknats. En förenklad modell genom finita elementmetoden har tagits fram där rullkropparnas styvhet modelleras på speciella kopplingselement, vilket förbrukar mindre beräkningstid men fortfarande ger ett korrekt resultat. Den största anledningen till utmattningsbrott hos lagren är lastens cykliska karaktär. Resultatet av beräkningen tyder på en ojämn fördelad belastning mellan rullkropparna där vissa rullkroppar ständigt upptar mer last än övriga. Dessutom har läget för maximala kontakttryck på rullkropparnas yta och hur det ändras med tiden beräknats. Lagret i vindkraftverkets pitchsystem kan tyckas relativt obetydligt jämfört med övriga komponenter, men en korrekt funktion av dessa är väsentlig för att uppnå en säker drift av vindkraftverken. Resultatet av denna studie belyser behovet av en alternativ lösning som är effektivare och optimerad för denna applikation. / The world today is heading towards a more sustainable lifestyle in every aspect ranging from the clothes worn, transportation and even energy generation. The change towards lowering the carbon footprint is a slow but steady process, in which the wind industry play a major role.The project’s aim is to study the behavior of the pitch bearing under constant wind load conditions, investigate the load distribution between the rolling elements in the bearing and finally to determine the contact conditions that exist between the raceways and the rollers. The bearing load is calculated by assuming a quasi-static loading as the blade completes one revolution. A simplified finite element model is then built where the stiffness of the rollers is modeled onto special connector elements, which consumes less computational resource and still delivers an accurate result.The cyclic nature of loading is one of the major source of fatigue failure of these bearings. The load distribution data suggests uneven loading of the rolling elements and how certain rollers in a particular position are always more heavily loaded than the others. The loading information is also used to map the position of maximum contact pressure on to the surface of the rollers and how it changes with time.At the first glance, the pitch bearing might appear relatively insignificant compared to rest of the components, but a proper functioning of these bearings is essential for safe operation of the WT (Wind Turbine). The results of this work have thrown light into the proficiency of these bearings and the need for an alternate solution that is more efficient and better optimized for this application.

American Association of State Highway and Transportation Officials (ASHTO) specifications have prescribed lateral load distribution factors to calculate the bending moments and shear forces for the design of highway bridges for civilian highway traffic. The maximum bending moments and shear forces caused by a wheel line load (or the entire vehicle) placed on the girders are multiplied by the distribution factors to calculate the design forces to include the effect of the load distribution laterally to the girders by the bridge deck. However, the use of these AASHTO distribution factors may not provide accurate estimate of the maximum forces for military vehicles, which usually have significantly different loading pattern than those of the civilian vehicles. Therefore, this study was conducted to develop new formulas for the lateral load distribution factors for military vehicles. The study considered six different types of military vehicles, three wheeled vehicles and the other three tracked vehicles. The bridge database used for developing AASHTO distribution factors formulas was also used in this study. The focus of this study was to develop the distribution factors formulas for three different types of bridges: steel girder bridges, pre-stressed concrete bridges, and concrete T-beam bridges. The bridges in each category were analyzed for the six types of military vehicles by the harmonic decomposition approach to calculate the distribution factor. This thesis provides a total of 52 new formulas for different types of vehicles, different types of bridges, bending moment and shear force values, interior and exterior girders, and for single and multiple lane loading cases. The distribution factors calculated with the formulas were compared with those calculated by direct analyses of the bridges to evaluate the accuracy of the proposed formulas. Comparisons were also made between the values calculated by the new formulas, post-LRFD formulas prescribed in 1996 AASHTO Standard Specification, and simple pre-LRFD formulas that were prescribed by AASHTO before 1994. / Master of Science

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The deterioration of the nation's civil infrastructure has prompted the investigation of numerous solutions to offset the problem. Some of these solutions have come in the form of innovative materials for new construction, whereas others have considered rehabilitation techniques for repairing existing infrastructure. A relatively new system that appears capable of encompassing both of these solution methodologies is the Sandwich Plate System (SPS), a composite bridge deck system that can be used in both new construction or for rehabilitation applications. SPS consists of steel face plates bonded to a rigid polyurethane core; a typical bridge application utilizes SPS primarily as a bridge deck acting compositely with conventional support girders. As a result of this technology being relatively new to the bridge market, design methods have yet to be established. This research aims to close this gap by investigating some of the key design issues considered to be limiting factors in implementation of SPS. The key issues that will be studied include lateral load distribution, dynamic load allowance and deck design methodologies. With SPS being new to the market, there has only been a single bridge application, limiting the investigations of in-service behavior. The Shenley Bridge was tested under live load conditions to determine in-service behavior with an emphasis on lateral load distribution and dynamic load allowance. Both static and dynamic testing were conducted. Results from the testing allowed for the determination of lateral load distribution factors and dynamic load allowance of an in-service SPS bridge. These results also provided a means to validate a finite element modeling approach which would could as the foundation for the remaining investigations on lateral load distribution and dynamic load allowance. The limited population of SPS bridges required the use of analytical methods of analysis for this study. These analytical models included finite element models and a stiffened plate model. The models were intended to be simple, but capable of predicting global response such as lateral load distribution and dynamic load allowance. The finite element models are shown to provide accurate predictions of the global response, but the stiffened plate approach was not as accurate. A parametric investigation, using the finite element models, was initiated to determine if the lateral load distribution characteristics and vibration response of SPS varied significantly from conventional systems. Results from this study suggest that the behavior of SPS does differ somewhat from conventional systems, but the response can be accommodated with current AASHTO LRFD bridge design provisions as a result of their conservativeness. In addition to characterizing global response, a deck design approach was developed. In this approach the SPS deck was represented as a plate structure, which allowed for the consideration of the key design limit states within the AASHTO LRFD specification. Based on the plate analyses, it was concluded that the design of SPS decks is stiffness-controlled as limited by the AASHTO LRFD specification deflection limits for lightweight metal decks. These limits allowed for the development of a method for sizing SPS decks to satisfy stiffness requirements. / Ph. D.

An innovative approach to possible construction or rehabilitation of bridge decks can be found in a bridge construction system called the Sandwich Plate System (SPS). The technology developed and patented by Intelligent Engineering Canada Limited in conjunction with an industry partner, Elastogran GmbH, a member of BASF, may be an effective alternative to traditional bridge rehabilitation techniques. Although the system's behavior has been studied the connection of the SPS deck to the supporting girders has not been investigated. Two types of connection are presented in this research. The use of a bent plate welded to the SPS deck and subsequently bolted to the supporting girder utilizing slip-critical connections has been utilized in the construction of a SPS bridge. A proposed SPS bridge system utilizes the top flange of the supporting girder welded directly to the SPS deck as the deck-to-girder connection. The fatigue performance of a deck-to-girder connection utilizing a bent plate welded to the deck and bolted to the supporting girder using slip-critical connections was tested in the Virginia Tech Materials and Structures Laboratory. The testing concluded that the fatigue performance of the welded and bolted bent plate connection was limited by the weld details and no slip occurred in the slip-critical connections. Finite element modeling of the two types of deck-to-girder connections was also used to determine influence of the connections on the local and global behavior of a SPS bridge system. A comparison of the different connection details showed that the connection utilizing the flange welded directly to the SPS deck significantly reduces the stresses at location of the welds in the connections, but the connection type has a limited influence on the global behavior of a SPS bridge. / Master of Science

A group of researchers, engineers, and government transportation officials have teamed up to design two bridges with simply-supported FRP composite structural beams. The Toms Creek Bridge, located in Blacksburg, Virginia, has been in service for six years. Meanwhile, the Route 601 Bridge, located in Sugar Grove, Virginia, has been in service for two years. Researchers have conducted load tests at both bridges to determine if their performance has changed during their respective service lives. The key design parameters under consideration are: deflection, wheel load distribution, and dynamic load allowance. The results from the latest tests in 2003 yield little, yet statistically significant, changes in these key factors for both bridges. Most differences appear to be largely temperature related, although the reason behind this effect is unclear. For the Toms Creek Bridge, the largest average values from the 2003 tests are 440 me for service strain, 0.43 in. (L/484) for service deflection, 0.08 (S/11.1) for wheel load distribution, and 0.64 for dynamic load allowance. The values for the Route 601 Bridge are 220 me, 0.38 in. (L/1230), 0.34 (S/10.2), and 0.14 for the same corresponding paramters. The recommended design values for the dynamic load allowance in both bridges have been revised upwards to 1.35 and 0.50 for the Toms Creek Bridge and Route 601 Bridge, respectively, to account for variability in the data. With these increased factors, the largest strain in the toms Creek Bridge and Route 601 Bridge would be less than 13% and 12%, respectively, of ultimate strain. Therefore, the two bridges continue to provide a large factor of safety against failure. / Master of Science

Die ersten Umlaufrädergetriebe wurden in Planetarien verwendet, um die Bewegung der Gestirne exakt aufzuzeigen. Bis in die zweite Hälfte des 19. Jahrhunderts wurden sie danach meist zur Lösung schwieriger Regelaufgaben verwendet. Erst durch größere Fortschritte in der Werkstoff- und Fertigungstechnik wurden Umlaufrädergetriebe als Drehmomentenwandler eingesetzt. Dadurch konnten die großen Vorteile der Umlaufrädergetriebe gegenüber Stirnradgetrieben in der Antriebstechnik genutzt werden. Umlaufrädergetriebe ermöglichen hohe Übersetzungen bei geringem Bauraum und Gewicht, da die Leistung über mehrere Zahnkontakte übertragen wird. Des Weiteren gibt es neben dem Zweiwellenbetrieb die Möglichkeit, im Dreiwellenbetrieb voneinander unabhängige Drehbewegungen zu überlagern. Dadurch sind beispielsweise Regelungsaufgaben bei Windenergieanlagen möglich. Dabei wird die Ungleichförmigkeit des Windes über einen zweiten drehzahlvariablen Antrieb ausgeglichen, damit am Abtrieb eine stets gleichmäßige Drehzahl am Generator anliegt. Weitere Vorteile sind die koaxiale Lage von Antrieb und Abtrieb und die symmetrische Bauform. MDESIGN LVR planet wurde entwickelt, um die Berechnung der Lastverteilung über der Zahnflanke und der Lastaufteilung auf die Planetenräder in Planetengetrieben zu übernehmen. Es ist möglich, diese Berechnung für geradverzahnte, einfachschräg- und doppeltschrägverzahnte Planetengetriebe im Zwei- und Dreiwellenbetrieb durchzuführen. Da doppelschrägverzahnte Planetengetriebe in Getrieben mit hohen Drehzahlen häufig in der Industrie verwendet werden, untersucht diese Forschungsarbeit die Theorie zur Umsetzung der Berechnung von Lastverteilungen unter dem Aspekt der Zeit – und Kosteneffizienz. Dabei sollen spezifische Probleme bei der Berechnung der Breitenlastverteilung über der Zahnflanke für doppelschrägverzahnte Planetengetriebe erfasst werden. Diese Probleme umfassen bei Doppelschrägverzahnung beispielsweise die hohen Torsionsverformungen, die Aufteilung der Last auf die Zahnhälften und die gegenseitige Beeinflussung der Verformung der Zahnhälften untereinander.