Calibration of Load and Resistance Factors in LRFD Foundation Design Specifications PDF Download
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Author: Zuocai Wang
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 146
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Book Description
This report summarizes the findings and recommendations on the impact of foundation settlements on the reliability of bridge superstructures. As a collaborative effort of an overall initiative for the development of LRFD foundation design specifications, this study is focused on the investigation of pros and cons for including foundation settlements in bridge designs under gravity loads. Settlement was modeled both probabilistically and deterministically. In the case of a random settlement variable, a lognormal distribution was used in reliability analysis with a fixed coefficient of variation of 0.25. Dead and live loads were modeled as random variables with normal and Gumbel Type I distributions, respectively. Considering the regional traffic condition on Missouri roadways, the effect of a live load reduction factor on bridge reliability was also investigated. Therefore, a total of eight cases were discussed with a complete combination of settlement modeling (mean and extreme values), design consideration (settlements included and excluded), and live load reduction (unreduced and reduced live loads). Based on extensive simulations on multi-span bridges, bridges designed without due consideration on settlements can tolerate an extreme settlement of L/3500 - L/450 under unreduced live loads and up to L/3500 under reduced live loads without resulting in a reliability index below 3.5 (L=span length). Depending upon span lengths settlements and has potential to reduce overall costs in bridge design. The second method may result in oversized foundations.
Author: Zuocai Wang
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 146
Get Book Here
Book Description
This report summarizes the findings and recommendations on the impact of foundation settlements on the reliability of bridge superstructures. As a collaborative effort of an overall initiative for the development of LRFD foundation design specifications, this study is focused on the investigation of pros and cons for including foundation settlements in bridge designs under gravity loads. Settlement was modeled both probabilistically and deterministically. In the case of a random settlement variable, a lognormal distribution was used in reliability analysis with a fixed coefficient of variation of 0.25. Dead and live loads were modeled as random variables with normal and Gumbel Type I distributions, respectively. Considering the regional traffic condition on Missouri roadways, the effect of a live load reduction factor on bridge reliability was also investigated. Therefore, a total of eight cases were discussed with a complete combination of settlement modeling (mean and extreme values), design consideration (settlements included and excluded), and live load reduction (unreduced and reduced live loads). Based on extensive simulations on multi-span bridges, bridges designed without due consideration on settlements can tolerate an extreme settlement of L/3500 - L/450 under unreduced live loads and up to L/3500 under reduced live loads without resulting in a reliability index below 3.5 (L=span length). Depending upon span lengths settlements and has potential to reduce overall costs in bridge design. The second method may result in oversized foundations.
Author: Andrew Boeckmann
Publisher:
ISBN: 9780309698467
Category : Geotechnical engineering
Languages : en
Pages : 0
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Book Description
More than 15 years have passed since the U.S. transportation industry started its transition from allowable stress design (ASD) to load and resistance factor design (LRFD). For geotechnical design, the AASHTO LRFD Bridge Design Specifications includes provisions that allow state departments of transportation (DOTs) to develop their own design methods and resistance factors. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 601: Practices for Local Calibration of LRFD Geotechnical Resistance Factors documents the extent to which state DOTs have developed agency-specific geotechnical design methods and resistance factors and also details the challenges of the development and benefits resulting from implementation of the methods.
Author: Michael C. McVay
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 202
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Book Description
Author: Samuel G. Paikowsky
Publisher: Transportation Research Board
ISBN: 0309087961
Category : Bridges
Languages : en
Pages : 87
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Book Description
Introduction and research approach -- Findings -- Interpretation, appraisal, and applications -- Conclusions and suggested research -- Bibliography -- Appendixes.
Author: William Andrew Singletary
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
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Book Description
Author: George G. Goble
Publisher: Transportation Research Board
ISBN: 9780309068543
Category : Bridges
Languages : en
Pages : 80
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Book Description
This synthesis report will be of interest to geotechnical, structural, and bridge engineers, especially those involved in the development and implementation of the geotechnical aspects of the AASHTO Bridge Code. The synthesis documents a review of geotechnical related LRFD specifications and their development worldwide to compare them with the current AASHTO LRFD Bridge Code. Design procedures for foundations, earth retaining structures, and culverts are summarized and compared with the methods specified by the AASHTO code. This TRB report provides information designed to assist engineers in implementing the geotechnical features of LRFD methods. Information for the synthesis was collected by surveying U.S. and Canadian transportation agencies and by conducting a literature search using domestic and international sources. Interviews were also conducted with selected international experts. The limited available experience in the United States and information from international practice are discussed to understand the problems that have arisen in order that solutions may be found. Based on the studies reported here, suggestions for improving the code are identified.
Author: Y. Honjo
Publisher: CRC Press
ISBN: 9789058093813
Category : Technology & Engineering
Languages : en
Pages : 474
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Book Description
The contributions contained in these proceedings are divided into three main sections: theme lectures presented during the pre-workshop lecture series; keynote lectures and other contributed papers; and a translation of the Japanese geotechnical design code.
Author: Patrick Arnold
Publisher: IOS Press
ISBN: 1614991626
Category : Science
Languages : en
Pages : 340
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Book Description
The ground is one of the most highly variable of engineering materials. It is therefore not surprising that geotechnical designs depend on local site conditions and local engineering experience. Engineering practices, relating to investigation and design methods site understanding and to safety levels acceptable to society, will therefore vary between different regions.The challenge in geotechnical engineering is to make use of worldwide geotechnical experience, established over many years, to aid in the development and harmonization of geotechnical design codes. Given the significant uncertainties involved, empiricism and engineering
Author: Murad Yusuf Abu-Farsakh
Publisher:
ISBN:
Category : Load factor design
Languages : en
Pages : 126
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Book Description
Author: Chong Tang
Publisher: CRC Press
ISBN: 0429658397
Category : Technology & Engineering
Languages : en
Pages : 589
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Book Description
Model Uncertainties in Foundation Design is unique in the compilation of the largest and the most diverse load test databases to date, covering many foundation types (shallow foundations, spudcans, driven piles, drilled shafts, rock sockets and helical piles) and a wide range of ground conditions (soil to soft rock). All databases with names prefixed by NUS are available upon request. This book presents a comprehensive evaluation of the model factor mean (bias) and coefficient of variation (COV) for ultimate and serviceability limit state based on these databases. These statistics can be used directly for AASHTO LRFD calibration. Besides load test databases, performance databases for other geo-structures and their model factor statistics are provided. Based on this extensive literature survey, a practical three-tier scheme for classifying the model uncertainty of geo-structures according to the model factor mean and COV is proposed. This empirically grounded scheme can underpin the calibration of resistance factors as a function of the degree of understanding – a concept already adopted in the Canadian Highway Bridge Design Code and being considered for the new draft for Eurocode 7 Part 1 (EN 1997-1:202x). The helical pile research in Chapter 7 was recognised by the 2020 ASCE Norman Medal.
