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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

Repair of GFRP Reinforced Concrete Bridge Barriers

Islam, Mohammad Rubiat 22 November 2012 (has links)
In present days both concrete bridge decks and barriers are being internally reinforced with corrosion free glass fiber-reinforced polymer (GFRP) bars. The design of bridge decks and barriers with internal GFRP reinforcement is well established and incorporated in current CAN/CSA-S6-06 code provisions. However, no test results are available on repairing GFRP-RC bridge barriers in case of damage caused by vehicle accidents. Therefore, this present research is aimed to conduct experiments on repairing full-scale GFRP-RC bridge barriers and provide much needed guidelines to repair such barriers. To do so, three full-scale 6-m long Performance Level-2 (PL-2) concrete bridge barriers (used in moderate to high traffic volume highways) totally reinforced with GFRP bars as per CAN/CSA-S6-06 were constructed. Then these barriers were tested at the middle and two edges of the barrier by applying monotonic load up to failure simulating vehicle crash test. Two different repair techniques, Splicing (Planting) and Near Surface Mounted (NSM), were used to repair the damaged barriers, and finally retested under the identical load condition that of intact barriers to evaluate the efficiency of the repair techniques. Test results were compared and discussed in terms of barrier wall capacity, mode of failure, deflection and strains in GFRP bars to evaluate the performance of intact barrier walls as well as efficiency of the repair techniques. It was concluded that GFRP-RC bridge barrier can be repaired using either Splicing (Planting) technique or NSM technique.
2

Repair of GFRP Reinforced Concrete Bridge Barriers

Islam, Mohammad Rubiat 22 November 2012 (has links)
In present days both concrete bridge decks and barriers are being internally reinforced with corrosion free glass fiber-reinforced polymer (GFRP) bars. The design of bridge decks and barriers with internal GFRP reinforcement is well established and incorporated in current CAN/CSA-S6-06 code provisions. However, no test results are available on repairing GFRP-RC bridge barriers in case of damage caused by vehicle accidents. Therefore, this present research is aimed to conduct experiments on repairing full-scale GFRP-RC bridge barriers and provide much needed guidelines to repair such barriers. To do so, three full-scale 6-m long Performance Level-2 (PL-2) concrete bridge barriers (used in moderate to high traffic volume highways) totally reinforced with GFRP bars as per CAN/CSA-S6-06 were constructed. Then these barriers were tested at the middle and two edges of the barrier by applying monotonic load up to failure simulating vehicle crash test. Two different repair techniques, Splicing (Planting) and Near Surface Mounted (NSM), were used to repair the damaged barriers, and finally retested under the identical load condition that of intact barriers to evaluate the efficiency of the repair techniques. Test results were compared and discussed in terms of barrier wall capacity, mode of failure, deflection and strains in GFRP bars to evaluate the performance of intact barrier walls as well as efficiency of the repair techniques. It was concluded that GFRP-RC bridge barrier can be repaired using either Splicing (Planting) technique or NSM technique.
3

Investigation of Glass Fibre Reinforced Polymer Reinforcing Bars as Internal Reinforcement for Concrete Structures

Johnson, David Tse Chuen 12 February 2010 (has links)
A study of the existing data shows that two areas of GFRP bar research among others are in need of investigation, the first being behaviour of GFRP bars at cold temperatures and the second being the behaviour of large diameter GFRP rods. Based on the results of experimental work performed, cold temperatures were found to have minimal effect on the mechanical properties of the GFRP bars tested. In addition, through beam testing, large 32mm diameter GFRP bars were found to not fail prematurely due to interlaminar shear failure. By evaluating the mechanical and durability properties of GFRP bars and behaviour of GFRP RC, it can be concluded that GFRP appears to be an adequate alternative reinforcement for concrete structures. Because of high strength, low stiffness and elastic behaviour of GFRP bars, issues of significant importance for reinforced concrete are bond development, influence of shear on member behaviour and member deformability.
4

Investigation of Glass Fibre Reinforced Polymer Reinforcing Bars as Internal Reinforcement for Concrete Structures

Johnson, David Tse Chuen 12 February 2010 (has links)
A study of the existing data shows that two areas of GFRP bar research among others are in need of investigation, the first being behaviour of GFRP bars at cold temperatures and the second being the behaviour of large diameter GFRP rods. Based on the results of experimental work performed, cold temperatures were found to have minimal effect on the mechanical properties of the GFRP bars tested. In addition, through beam testing, large 32mm diameter GFRP bars were found to not fail prematurely due to interlaminar shear failure. By evaluating the mechanical and durability properties of GFRP bars and behaviour of GFRP RC, it can be concluded that GFRP appears to be an adequate alternative reinforcement for concrete structures. Because of high strength, low stiffness and elastic behaviour of GFRP bars, issues of significant importance for reinforced concrete are bond development, influence of shear on member behaviour and member deformability.
5

Analysis and Design of a New Generation GFRP Wind Turbine Tower

Hasan, Md Sofiq 11 September 2013 (has links)
The focus of the research program is to analysis and design of a new generation glass-fibre reinforced polymer (GFRP) wind turbine tower for full scale prototype testing. The study includes the finite element analyses of different tower section configurations, the parametrical study of different variables, the selection of appropriate configuration and dimensions, and the finalization of the section. The design section arrived from this study has the bottom outer diameter of 1350 mm, the top outer diameter of 800 mm, the constant inner diameter of 600 mm and uniform wall thickness of 11.25 mm. The tower is also analysed and compared with a steel tapered tower. The analysis results indicate that the tower is considered as a soft-soft tower and that, in general, the lateral deflection limitation is a governing factor in the design of GFRP wind turbine tower. The proposed section met all the design requirements and the fabrication drawings are provided for the further study of full scale test.
6

Behaviour of GFRP prestressed concrete straps

El-Sayed, Yasmine 30 September 2011 (has links)
Steel straps are being used for confinement purposes of steel-free bridge deck slab. The objective of this study was to use GFRP prestressed concrete straps as an alternative to steel straps, and assess the effect of the alkaline concrete environment on the long-term performance of GFRP. Each strap was 160 x100 mm2 in cross section, 2000 mm in length and pre-tensioned with two 16 mm diameter GFRP strands. The experimental study included testing three sets of concrete straps, pre-stressed at 35%, 45%, and 55% of ultimate strength of GFRP. The straps were tested in tension after being subjected to temperatures from -25oC to +40 oC in an environmental chamber. Another two sets of straps were cast and tested two and a half years later. The control and conditioned samples achieved comparable results proving that GFRP can withstand prestressing levels higher than 25% and up to 35% of their ultimate strength.
7

Analysis and Design of a New Generation GFRP Wind Turbine Tower

Hasan, Md Sofiq 11 September 2013 (has links)
The focus of the research program is to analysis and design of a new generation glass-fibre reinforced polymer (GFRP) wind turbine tower for full scale prototype testing. The study includes the finite element analyses of different tower section configurations, the parametrical study of different variables, the selection of appropriate configuration and dimensions, and the finalization of the section. The design section arrived from this study has the bottom outer diameter of 1350 mm, the top outer diameter of 800 mm, the constant inner diameter of 600 mm and uniform wall thickness of 11.25 mm. The tower is also analysed and compared with a steel tapered tower. The analysis results indicate that the tower is considered as a soft-soft tower and that, in general, the lateral deflection limitation is a governing factor in the design of GFRP wind turbine tower. The proposed section met all the design requirements and the fabrication drawings are provided for the further study of full scale test.
8

STRUCTURAL AND STEADY-STATE THERMAL EXPERIMENTAL INVESTIGATIONS OF AN INSULATED SANDWICH PANEL

Woltman, Gregory 06 May 2014 (has links)
Concrete-Insulation-Concrete Sandwich Panels with Glass Fibre Reinforced Polymer (GFRP) shear connectors can be a solution to increasing energy efficiency in building envelopes, while also providing many architectural, structural, and economic benefits for building designs. This study consists of extensive experimental investigation of the shear and thermal properties of a unique sandwich panel design, incorporating GFRP shear connectors and a concrete “stud” system. The goal of this study is to expand upon the knowledge of alternative connectors’ effect on structural and thermal properties of sandwich panels, and to develop a thermally, structurally, and economically efficient panel. In the structural phase fifty 254x254x900 mm specimens representing segments of the precast sandwich wall, comprising two concrete wythes and a concrete stud surrounded by insulation foam, were tested in a double shear configuration. Three types of GFRP connectors produced from available sand-coated and threaded rods were tested and compared to conventional steel and polymeric connectors. GFRP connector diameters varied from 6 to 13 mm, and spacing varied from 80 to 300 mm. Both circular and rectangular cross-sections were examined, along with various end treatments to compare with simple straight embedment. The shear strength of GFRP connectors ranged from 60 to 112 MPa, significantly higher than polymeric connectors but lower than steel connectors. As the connectors bridged a small gap of insulation between the concrete wythe and stud, their shear strength was lower than manufacturer reported values due to the presence of some bending. Varying the size, spacing, cross-section shape or end treatment of connectors had insignificant effect on their strength. The connectors failed by longitudinal delamination then transverse shear, but did not pull out of the concrete wythe. Adhesion bond between concrete and insulation was significant and contributed about 28% of resistance, but was too variable for use in design. In the thermal testing phase, ten 254x1550x2400 full-scale specimens were tested in a purpose-built hot box apparatus under steady-state conditions. GFRP connectors showed minimal thermal bridging regardless of cross-section area or spacing, while steel connectors demonstrated significant thermal bridging in recorded temperatures despite a smaller cross-section area, and were clearly visible in thermal imaging. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-05-06 13:32:38.896
9

Behaviour of GFRP prestressed concrete straps

El-Sayed, Yasmine 30 September 2011 (has links)
Steel straps are being used for confinement purposes of steel-free bridge deck slab. The objective of this study was to use GFRP prestressed concrete straps as an alternative to steel straps, and assess the effect of the alkaline concrete environment on the long-term performance of GFRP. Each strap was 160 x100 mm2 in cross section, 2000 mm in length and pre-tensioned with two 16 mm diameter GFRP strands. The experimental study included testing three sets of concrete straps, pre-stressed at 35%, 45%, and 55% of ultimate strength of GFRP. The straps were tested in tension after being subjected to temperatures from -25oC to +40 oC in an environmental chamber. Another two sets of straps were cast and tested two and a half years later. The control and conditioned samples achieved comparable results proving that GFRP can withstand prestressing levels higher than 25% and up to 35% of their ultimate strength.
10

Análise teórica de vigas pré-moldadas de concreto com armadura de aço e de polímero reforçado com fibra de vidro em meio altamente agressivo / Theoretical analysis of precast concrete beams with steel bars and polymer reinforced with glass fiber in aggressive environmental sites

Micali, Roberto Mauricio 29 April 2010 (has links)
Este trabalho analisou o comportamento estrutural de polímeros reforçados com fibra de vidro - PRFV em elementos pré-moldados de concreto, com aplicações específicas em vigas de concreto. Realizou-se um estudo comparativo do comportamento de vigas pré-moldadas reforçadas com armadura convencional, segundo a norma brasileira NBR 6118:2003, e reforçadas com armadura de barras pultrudadas de PRFV, segundo o ACI 440.1R-06. O estudo visa obter subsídios para a aplicação de barras de reforço de PRFV, em relação ao Estado Limite de Serviço - ELS, em obras realizadas em regiões de alta agressividade ambiental. Posteriormente fez-se os mesmos modelos de cálculo em elementos finitos, onde foram comparados e analisados os resultados obtidos com o cálculo prescrito pelas normas. Nem todos os parâmetros da norma americana foram inseridos, uma vez que alguns coeficientes internos que contam com efeitos sísmicos e com a neve estão embutidos nos cálculos. Os resultados obtidos, principalmente no cisalhamento, foram altamente satisfatórios, validando a aplicação do PRFV nas vigas consideradas. / This work studied the behavior of precast beams when subjected to shear stress according to the brazilian standard NBR 6118:2003 reinforced with steel bar compared to the american standard ACI 440.1R-06 when the structural member was reinforced with glass fiber reinforced polymer - GFRP pultruded bars. The goal of this work is to acquire subsidies to apply the GFRP in aggressive environmental sites. Also the same model calculations were performed by using Finite Element Method and compared to the results of the calculation prescribed by the standards. Some parameters indicated in the ACI standard were not followed since they are related to seismic and snow effects. The obtained results mainly in shear loading were highly satisfactory which validates the use of GFRP in the considered beams.

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