Type of Document Master's Thesis Author Chen, Jou-Jun Robert URN etd-09082012-040034 Title Load and resistance factor design of shallow foundations for bridges Degree Master of Science Department Civil Engineering Advisory Committee
Advisor Name Title Rojiani, Kamal B. Committee Chair Barker, Richard M. Committee Member Duncan, James Michael Committee Member Keywords
Date of Defense 1989-12-15 Availability restricted Abstract
Load Factor Design (LFD), adopted by AASHTO in the mid-1970, is currently used for bridge superstructure design. However, the AASHTO specifications do not have any LFD provisions for foundations. In this study, a LFD format for the design of shallow foundations for bridges is developed.
Design equations for reliability analysis are formulated. Uncertainties in design parameters for ultimate and serviceability limit states are evaluated. A random field model is employed to investigate the combined inherent spatial variability and systematic error for serviceability limit state. Advanced first order second moment method is then used to compute reliability indices inherent in the current AASHTO specifications. Reliability indices for ultimate and serviceability limit states with different safety factors and dead to live load ratios are investigated. Reliability indices for ultimate limit state are found to be in the range of 2.3 to 3.4, for safety factors between 2 and 3. This is shown to be in good agreement with Meyerhof’s conclusion (1970). Reliability indices for serviceability limit state are found to be in the range of 0.43 to 1.40, for ratios of allowable to actual settlement between 1.0 to 2.0. This appears to be in good agreement with what may be expected. Performance factors are then determined using target reliability indices selected on the basis of existing risk levels.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access LD5655.V855_1989.C5343.pdf 3.89 Mb 00:18:01 00:09:16 00:08:06 00:04:03 00:00:20next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.