Author: Paul Zia
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 98

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Author: Luis Alexander Mata
Publisher:
ISBN:
Category :
Languages : en
Pages : 119

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Keywords: bridge beam, girder, creep, flexural modulus, modulus of elasticity, prestressing, self-consolidating concrete, shrinkage, strength.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Self-Consolidating Concrete (SCC) was first developed in Japan almost 15 years ago, and it was not until the late 1990's that the U.S precast concrete industry applied the technology to architectural and structural building elements. This study describes the first experience of using SCC for prestressed concrete bridge girders in North Carolina. A multiple-span bridge is currently under construction in eastern North Carolina using one hundred thirty AASHTO Type III girders, each 54.8 ft (16.7 m) long (NCDOT Project 8.1170903). Three girders from one production line of five girders were selected for evaluation. Two of the girders were cast with SCC and one with conventional concrete as the control. The plastic and hardened properties of both the SCC and the conventional concrete were monitored and measured. The fresh properties of SCC included unit weight, air content, slump flow, Visual Stability Index (VSI), and passing ability as measured by J-ring and L-box. Hardened concrete tests on SCC and conventional concrete included compressive strength, static elastic modulus, elastic modulus based on resonance frequency ('dynamic' modulus) at different ages, along with creep and shrinkage. The prestressing force in the girders was monitored by load cells. Finally, the three girders were tested in flexure up to the design service load to determine and compare their load-deformation characteristics. In general, two AASTHO Type III girders were successfully cast without any vibration using SCC, and exhibited virtually identical load-deflection relationships up to the design service load than that of the conventional concrete girder. SCC showed lower elastic modulus after strength adjustment, and higher creep and shrinkage than conventional concrete.

Author: Jacob G. Choate
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 278

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Author: Kamal Khayat
Publisher: Transportation Research Board
ISBN: 0309117666
Category : Bridges
Languages : en
Pages : 99

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At head of title: National Cooperative Highway Research Program.

Author: Bassem O. Andrawes
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 56

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Author: Alexander Michael Griffin
Publisher:
ISBN:
Category : Fiber-reinforced concrete
Languages : en
Pages : 190

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"As the nation's infrastructure continues to age, advanced concrete technologies have been developed to both reduce a structure's costs and increase its life expectancy. Since the early 1990's, self-consolidating concrete (SCC) has been one of these technologies. Many, however, have been reluctant to implement SCC in highway girders due to the mixture constituents. One of these concerns is the reduced content and size of the coarse aggregate. These differences in the concrete potentially hinder SCC's mechanical properties and shear resistance. Additionally, for high strength concretes (HSC) with weaker aggregates, shear cracks tend to propagate through the coarse aggregate, reducing the aggregate interlock component of the shear resistance. This study aimed at assessing the web-shear strength both with and without web reinforcement of two precast-prestressed Nebraska University (NU) 53 girders fabricated with high strength self-consolidating concrete (HS-SCC). The results were compared to the ACI 318 (2011) and AASHTO LRFD (2012) code estimates, and a finite element model (FEM) package, Response 2000. ATENA Engineering, a finite element analysis (FEA) program, was also used to evaluate the qualitative results, specifically crack patterns and the effect of the coarse aggregate content and size. A prestressed concrete database was also constructed to assess the effect of the reduced coarse aggregate content on the shear capacity of HS-SCC in prestressed concrete members. The mechanical properties of the HS-SCC mix were also tested and compared to relevant empirical equations. The HS-SCC mix investigated in this study proves to be a viable cost-saving alternative for bridge superstructure elements"--Abstract, page iii.

Author: Junwon Seo
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 165

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Author: Bulent Erkmen
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 347

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Researchers conducted an experimental program to investigate the viability of producing self-consolidating concrete (SCC) using locally available aggregate, and the viability of its use in the production of precast prestressed concrete bridge girders for the State of Minnesota. Six precast prestressed bridge girders were cast using four SCC and two conventional concrete mixes. Variations in the mixes included cementitious materials (ASTM Type I and III cement and Class C fly ash), natural gravel and crushed stone as coarse aggregate, and several admixtures. The girders were instrumented to monitor transfer length, camber, and prestress losses. In addition, companion cylinders were cast to measure the compressive strength and modulus of elasticity, and to monitor the creep and shrinkage over time. The viability of using several test methods to evaluate SCC fresh properties was also investigated. The test results indicated that the overall performance of the SCC girders was comparable to that of the conventional concrete girders. The measured, predicted, and calculated prestress losses were generally in good agreement. The study indicated that creep and shrinkage material models developed based on companion cylinder creep and shrinkage data can be used to reasonably predict measured prestress losses of both conventional and SCC prestressed bridge girders.

Author: Andrew M. Pozolo
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Self-consolidating concrete (SCC) is a workable yet stable concrete which flows easily and consolidates under its own weight. Its unique properties can substantially reduce the labor required to pour complex or heavily reinforced structural members. Over the past decade, the American precast industry has taken significant strides to adopt SCC in commercial projects, though concern about early-age bond behavior has limited the material0́9s application in prestressed members. A keen understanding of SCC0́9s bond strength, including its impact on transfer and development lengths in prestressed members, is essential to safely implement SCC in prestressed design. The Illinois Department of Transportation (IDOT) has sponsored a three-phase study exploring the bond behavior of steel strands in prestressed bridge girders. In the first phase, 56 pullout tests were conducted to compare the performance of seven-wire strands embedded in SCC and conventionally-consolidated concrete blocks. In the second phase, transfer lengths of prestressing strands in two SCC hollow box girders and two SCC I-girders were determined experimentally. In the third phase, the development length of strands in the two box girders was determined through a series of iterative flexural tests. This thesis details the three phases of the IDOT study and compares results to industry standards and requirements of the American Concrete Institute and the American Association of State Highway and Transportation Officials. Results are also compared to analytical methods proposed in the literature. Additionally, a systematic method is developed to predict transfer lengths in full-scale specimens using pullout test data and finite element analysis. The proposed method may be useful when large-scale testing is impractical in terms of time or cost.