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Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 242
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Book Description
"A long-term study of the settlement performance of 21 bridge foundations supported on cohesionless soil-sand or silt- was completed to provide a reliable data base for engineering evaluation"--Abstract
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 242
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Book Description
"A long-term study of the settlement performance of 21 bridge foundations supported on cohesionless soil-sand or silt- was completed to provide a reliable data base for engineering evaluation"--Abstract
Author: Shad M. Sargand
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 338
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Book Description
Spread footing foundations have been used to support various types of civil engineering structures over the years. However, one type of structure to which they have not seen much widespread application is highway bridges. This is because bridge engineers generally take a rather conservative approach and specify deep foundations, such as H-piles and drilled pier shafts, to support the bridge superstructure weight and live loads. In the current research project, the ORITE team continued to investigate several technical aspects related to spread footing foundations. Four additional spread footings constructed at two interstate highway construction sites were instrumented with modern sensors and monitored through construction stages and beyond. The spread footing design methods presented in the AASHTO LRFD Bridge Design Specifications (2004) were validated on the basis of the field performance data accumulated during the ORITE research project(s). Twelve SPT-based settlement prediction methods (for footings resting on cohesionless or slightly cohesive soils) were evaluated in light of the field performance data. General performance analysis of spread footing foundations at bridge construction sites was made to draw some guidelines concerning the use of spread footings for supporting highway bridge structures. Finally, detailed cost comparisons were made between spread footing and pile foundation options. Overall, the results of the research project indicated that: 1) spread footing can be a viable option as the highway bridge foundation; and 2) the design methods presented in the AASHTO LRFD Bridge Design Specifications (2004) appear to be satisfactory.
Author: Naser M. Abu-Hejleh
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Book Description
Recent FHWA national surveys revealed that State Departments of Transportation (DOTs) have safely and economically constructed highway bridges supported on spread footings bearing on competent and improved natural soils as well as engineered granular and MSE fills, and that many State DOTs may be missing an opportunity to save time and costs by not doing so more often. The goal of this report is to promote the consideration and use of spread footings on soils when appropriate to support highway bridges. Initially, perceived obstacles in using spread footings are identified. Then, the report presents recommendations to address these obstacles and a guidance to help State DOTs implementing these recommendations that are centered around: 1) deployment of AASHTO and FHWA technical resources; 2) highlighting practices of State DOTs that actively use spread footings, especially for selection of spread footings; 3) a performance review of bridges constructed with spread footings bearing on soils; and 4) LRFD implementation for spread footings. State DOTs' concerns with spread footings on engineered and MSE fills and with integral abutments are addressed. Consideration of load tests on spread footings, instrumentation programs for bridges with spread footings, and deployment of adequate subsurface investigation and construction programs are recommended. The main concern of State DOTs that do not consider spread footings is excessive settlement of bridges. This report advances a rational procedure for settlement analysis of bridges supported on spread footings bearing on soils. This procedure and the results of the national surveys demonstrate that bridges with spread footings on soil can perform very well with respect to settlement. Development of LRFD design bearing resistances for footings on various types of soils is discussed. Based on the previous recommendations, the report finally provides a technical resource for State DOTs to develop LRFD guidance that would allow selection of spread footings in design when appropriate, and development of accurate and economical design methods for spread footings.
Author: Naser M. Abu-Hejleh
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Book Description
Recent FHWA national surveys revealed that State Departments of Transportation (DOTs) have safely and economically constructed highway bridges supported on spread footings bearing on competent and improved natural soils as well as engineered granular and MSE fills, and that many State DOTs may be missing an opportunity to save time and costs by not doing so more often. The goal of this report is to promote the consideration and use of spread footings on soils when appropriate to support highway bridges. Initially, perceived obstacles in using spread footings are identified. Then, the report presents recommendations to address these obstacles and a guidance to help State DOTs implementing these recommendations that are centered around: 1) deployment of AASHTO and FHWA technical resources; 2) highlighting practices of State DOTs that actively use spread footings, especially for selection of spread footings; 3) a performance review of bridges constructed with spread footings bearing on soils; and 4) LRFD implementation for spread footings. State DOTs' concerns with spread footings on engineered and MSE fills and with integral abutments are addressed. Consideration of load tests on spread footings, instrumentation programs for bridges with spread footings, and deployment of adequate subsurface investigation and construction programs are recommended. The main concern of State DOTs that do not consider spread footings is excessive settlement of bridges. This report advances a rational procedure for settlement analysis of bridges supported on spread footings bearing on soils. This procedure and the results of the national surveys demonstrate that bridges with spread footings on soil can perform very well with respect to settlement. Development of LRFD design bearing resistances for footings on various types of soils is discussed. Based on the previous recommendations, the report finally provides a technical resource for State DOTs to develop LRFD guidance that would allow selection of spread footings in design when appropriate, and development of accurate and economical design methods for spread footings.
Author: Naresh C. Samtani
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 84
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Book Description
The FHWA believes that spread footings on soils are underutilized because designers encounter one or more of the following obstacles: (a) limited knowledge of AASHTO/FHWA technical references that pertain to spread footings on soils to support bridges; (b) limited knowledge of adequate performance data for spread footings; (c) unrealistic tolerable settlement criteria; (d) overestimation of loads used to calculate settlement; and (e) the use of conservative settlement prediction methods. These obstacles have resulted in institutional biases and overly conservative and excessively costly institutional processes that lead to the unnecessary use of costlier deep foundation systems. The primary goal of this report is to promote the use of spread footings bearing on competent natural soils, improved soils, and engineered fill materials as a routine alternative to deep foundations for support of bridges by addressing the factors identified above. Documented performance data is used to make this case. The report also presents powerful concepts such as construction-point analysis and angular distortions to demonstrate the efficacy of using spread footings. Implementation of these concepts requires only that conventional computations be taken one step further without any requirement for advanced computational skills. The report presents sources of information that agencies and designers can use as references in their project applications. The report contains comprehensive appendices that treat in detail many of the topics discussed in the report. For example, one such appendix provides an introduction to Load and Resistance Factor Design (LRFD) that permits a rational approach to the consideration of spread footings on soils as a feasible alternative to deep foundations.
Author: Sedtha Mahasantipiya
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 0
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Author: Albert F. DiMillio
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 48
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Abstract A visual inspection was made of the structural condition of 148 highway bridges supported by spread footings on compacted fill throughout the State of Washington. The approach pavements and other bridge appurtenances were also inspected for damage or distress that could be attributed to the use of spread footings on compacted fill. This review, in conjunction with detailed investigations of the foundation movement of 28 selected bridges, was used to evaluate the performance of spread footings on compacted fills. It was concluded that spread footings can provide a satisfactory alternative to piles especially when high embankments of good quality borrow materials are constructed over satisfactory foundation soils . None of the bridges investigated displayed any safety problems serious functional distress. All bridges were in good condition and many were found to be in very good condition. In addition to the performance evaluation, cost-effectiveness analyses and tolerable movement correlation studies were made to further substantiate the feasibility of using spread footings in lieu of expensive deep foundation systems. Cost analyses showed spread footings were 50-65 percent cheaper than the a1 ternate choice o f pile foundations. Foundation movement studies showed t h a t these bridges have easily tolerated differential settlements of 1-3 inches (25-75 mm) without serious distress.
Author: Antoine E. Rocca
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 322
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Author: Chatchawahn Payoongwong
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 0
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Author: Jean-Louis Briaud
Publisher: Transportation Research Board
ISBN: 9780309060073
Category :
Languages : en
Pages : 88
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Book Description
