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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Shear Connections for the Development of a Full-Depth Precast Concrete Deck System

Henley, Matthew D. 2009 May 1900 (has links)
A full-depth precast concrete deck system presents several safety, timeline, and cost benefits to the process of constructing a bridge, however the relevant professional codes do not provide dependable design models due to the limited amount of research conducted on the subject. One area lacking design direction is the development of a shear connection between the full-depth precast deck and a precast concrete girder via a pocket-haunch-connector system. Push-off tests are performed to investigate the effects of various pre- and post-installed shear connectors, haunch height, surface roughness, grouping effects, and grout composition as compared to cast-in-place specimens. The experimental results are presented along with a method for normalizing the variations of results by connection yield strength. This method is used to evaluate each connector type and connection parameter investigated. Ensuring sufficient shear reinforcement within the beam near the shear connector anchorage is found to be a vital aspect of holistic design. A simplified design procedure is outlined, the design connection forcedisplacement behavior is shown, and an example problem is solved. Recommendations for additions and modifications to current code and practice are prescribed.
2

Live-Load Test and Computer Modeling of a Pre-Cast Concrete Deck, Steel Girder Bridge, and a Cast-in-Place Concrete Box Girder Bridge

Pockels, Leonardo A. 01 December 2009 (has links)
The scheduled replacement of the 8th North Bridge, in Salt Lake City, UT, presented a unique opportunity to test a pre-cast concrete deck, steel girder bridge. A live-load test was performed under the directions of Bridge Diagnostic Inc (BDI) and Utah State University. Six different load paths were chosen to be tested. The recorded data was used to calibrate a finite-element model of this superstructure, which was created using solid, shell, and frame elements. A comparison between the measured and finite-element response was performed and it was determined that the finite-element model replicated the measured results within 3.5% of the actual values. This model was later used to obtain theoretical live-load distribution factors, which were compared with the AASHTO LRFD Specifications estimations. The analysis was performed for the actual condition of the bridge and the original case of the bridge, which included sidewalks on both sides. The comparison showed that the code over predicted the behavior of the actual structure by 10%. For the original case, the code's estimation differed by as much as 45% of the theoretical values. Another opportunity was presented to test the behavior of a cast-in-place concrete box girder bridge in Joaquin County, CA. The Walnut Grove Bridge was tested by BDI at the request of Utah State University. The test was performed with six different load paths and the recorded data was used to calibrate a finite-element model of the structure. The bridge was modeled using shell elements and the supports were modeled using solid elements. The model was shown to replicate the actual behavior of the bridge to within 3% of the measured values. The calibrated model was then used to calculate the theoretical live-load distribution factors, which allowed a comparison of the results with the AASHTOO LRFD Specifications equations. This analysis was performed for the real conditions of the bridge and a second case where intermediate diaphragms were not included. It was determined that the code's equations estimated the behavior of the interior girder more accurately for the second model (within 10%) than the real model of the bridge (within 20%).
3

Evaluation of AASHTO design specifications for cast-in-place continuous bridge deck using remote sensing technique

Mehranipornejad, Ebrahim 01 June 2006 (has links)
This research project concerns the construction, testing, and remote health monitoring of the first smart bridge structure in Florida, the East Bay bridge in Gibsonton, Hillsborough County. The East Bay Bridge is a four span, continuous, deck-type structure with a total length of 120' and width of 55'. The superstructure consists of an 18'' cast-in-place reinforced concrete slab, and is supported on pre-stressed pile bents, each consisting of 5 piles. The smart sensors used for remote health monitoring are the newly emerged Fabry --Perot (FP) Fiber Optic Sensors, and are both surface-mounted and embedded in the concrete deck.Static and Dynamic testing of the bridge were performed using loaded SU-4 trucks, and a finite element model for the bridge was developed for the test cases using commercial software packages. In addition, the smart sensors were connected to a data acquisition system permanently installed on-site. This system could be accessed through regular phone lin es, which permits the evaluation of the bridge behavior under live traffic loads.Currently, these live structural data under traffic loading are transmitted to Hillsborough County's bridge maintenance office to assist in the health evaluation and maintenance of the bridge.AASHTO LRFD Design Code has been investigated using analytical and laboratory test but no attempt has been made to verify its relative outlook with respect to Allowable Strength Design (ASD) and AASHTO Standard Specifications (LFD) in a real field test. The likely reason for could have been the lack of accurate and reliable sensing systems.The data collected as well as the analytical studies through out this research, suggest that current LRFD design specifications for deck-type bridges are conservative. The technology developed under this work will enable practical, cost-effective, and reliable systematic maintenance of bridge structures, and the study will provide a unique opportunity for future growth of this tech nology in the state of Florida and in other states and finally, long term collected data can be used to keep the design codes in check.
4

Alternativní návrh železničního mostu v km 19,459 tratě Děčín - Oldřichov přes dálnici D8 / Alternative design of structure of railway bridge in km 19,459 railway track Děčín – Oldřichov over the highway D8

Bilík, Ondřej January 2013 (has links)
This master thesis contents alternative design of three spans single-railed steel bridge and its main bearing structures. The bridge is located in km 19,459 on the track Děčín - Oldřichov. Crossing barrier is highway D8. The span is 28,38 m + 41,28 m + 28,38 m. The main bearing structure consists of solid steel beams with variable height of 2,3 m ~ 3,8 m, which are in the axial distance of 6 meters and reinforced with lengthwise and transverse stiffeners. The lower bridge deck with a continuous ballast bed consists of reinforced concrete bath, which is coupled with steel cross beams. All elements of the structure are made out of steel S 355. For design of the following standards have been used: ČSN EN 1991-2, ČSN EN 1993, ČSN EN 1994 – 2.
5

Behavior of Bridge with Internally Cured Concrete Deck under Environmental and TruckLoading

Hamid, Waleed Khalid January 2020 (has links)
No description available.
6

Sandwichbauteile mit gefalteten und gekrümmten Betondeckschichten

Stark, Alexander, Hegger, Josef 21 July 2022 (has links)
In der aktuellen Baupraxis werden mit Standard-Tragelementen meist rechteckige Grundrisse erzeugt. Ausgenommen sind weitspannende Konstruktionen, wie Kuppeln von Domen oder Kühltürme von Kraftwerken. Im Gegensatz dazu waren Schalen aus Stahlbeton im Hochbau im vergangenen Jahrhundert weit verbreitet. Dazu wurden in der Regel große Strukturen in situ betoniert. Zusätzlich wurden weit spannende Fertigteile mit relativ geringer Breite hergestellt. Diese Faltwerke oder doppelt gekrümmten Elemente wurden zum Teil mit einer Dicke von weniger als 10 cm realisiert und häuf g im sofortigen Verbund vorgespannt. Bedenken hinsichtlich der Korrosionsbeständigkeit können ein Grund dafür gewesen sein, dass solche Konstruktionen heute üblicherweise nicht mehr gebaut werden. [Aus. Einleitung] / In current building practice, standard load-bearing elements are mostly of rectangular shape. Exceptions are large shell structures, such as cupolas of domes or cooling towers of power plants. In contrast, shells made of reinforced concrete (RC were widely applied for building construction in the last century. For this purpose, large structures were usually cast in situ. Additionally, long-span precast elements with limited width were produced. These folded plate or doubly curved elements were realised with a thickness of less than 10 cm and usually prestressed with steel tendons. Concerns regarding the corrosion resistance might have been a reason that such constructions are not build regularly today. [Off: Introduction]
7

Základní umělecká škola / Elementary Art School

Šimíčková, Alžběta January 2020 (has links)
The aim of this thesis is to make a project documentation of building School of art. It´s a brick object with partial basement and there are 2 aboveground floors. The entrance of the house is situated north. The object has grand plan which is shape of the letter U and its roofed by flat roof with waterproofing from modified waterproofing strips. The peripheral masonry on the above-ground floors is designed from clay masonry POROTHERM and from permanent formwork Diton in the basement. Ceiling constructions are designed from prestressed concrete deck slab Spiroll. The whole building is insulated by contact thermal insulation system. When designing the external appearance of the building the regulations of the surrounding buildings, which consist of houses with flat roofs, were taken into account. The color and material solutions were also based on these principles. The combination of white and brick colors creates a modern look, which enhances the horizontal separation of individual floors by contrasting color line in gray. The premises of the new school also include large outdoor atrium spaces and a park area south of the atrium, which can be used for outdoor teaching and public productions.
8

Evaluation and Structural Behavior of Deteriorated Precast, Prestressed Concrete Box Beams

Ryan T Whelchel (7874897) 22 November 2019 (has links)
Adjacent precast, prestressed box beam bridges have a history of poor performance and have been observed to exhibit common types of deterioration including longitudinal cracking, concrete spalling, and deterioration of the concrete top flange. The nature of these types of deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are being made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. Therefore, the objective of this research is to develop improved recommendations for the inspection, load rating, and design of adjacent box beam bridges. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. The deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedure are provided along with design recommendations for the next generation of box beam bridges.

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