Service limit state resistance factors for drilled shafts

Misra, Anil; Roberts, Lance A.

doi:10.1680/geot.2008.3605

Cited by 26 publications

(11 citation statements)

References 17 publications

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“…Since the resistance factor was determined to be a function of normalized load, the design of SLS for drilled shafts becomes a cumbersome process, meaning the engineers need to obtain different resistance factors for different loading or nominal shaft capacity which in turn depends in shaft dimensions. This is possibly the reason why Zhang and Chu (2009) proposed SLS resistance factors strictly only for use with nominal working loads equal to 50 percent of the ultimate foundation capacity, and the resistance factors by Misra and Roberts (2009) were proposed only for specific foundation dimensions. The design procedure proposed presented below overcomes this cumbersomeness and provides a flexibility in design of drilled shaft foundation at SLS.…”

Section: Resultsmentioning

confidence: 99%

“…The partial factors are roughly equivalent to resistance factors that range from 0.2 to 0.5; however, the partial factors are strictly only appropriate for use with nominal working loads equal to 50 percent of the ultimate foundation capacity. Resistance factors proposed by Misra and Roberts (2009) for establishing an allowable shaft capacity at the SLS range from approximately 0.25 to 0.55 for a target reliability index of 2.6. However, the resistance factors were found to depend on foundation length and diameter in addition to the variability of the soil-shaft interface resistance.…”

Section: Introductionmentioning

confidence: 99%

“…Shaft head displacement calculation using the t-z method: The load transfer method, or t-z method, is often used to calculate shaft head displacement ( O'Neil and Reese, 1999 ; Misra and Roberts, 2009 ; Brown et al., 2010 ). The method requires predictive models for ultimate unit side and tip resistance well as load transfer models to predict mobilization of resistance along the shaft.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic analysis and resistance factor calibration for deep foundation design using Monte Carlo simulation

Loehr

Smith

2018

Heliyon

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The method of incorporating the sources of parameter uncertainty is crucial when conducting probabilistic analysis for service limit state (SLS) design of a deep foundation. This paper describes the method of using Monte Carlo simulation for probabilistic analyses and for calibration of resistance factors of drilled shafts at SLS. The paper presents discussions on the finding of an impossible case, where the different combinations of load, variability of soil strength and target probability of failure made it impossible to calibrate the SLS resistance factors. Resistance factors for drilled shafts in shale are introduced, and were found to be responsive to load levels. The higher load level, the lower the resistance factor. These findings help smooth the transition from allowable stress design to load and resistance factor design for geotechnical engineers.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Probabilistic analysis and resistance factor calibration for deep foundation design using Monte Carlo simulation

Loehr

Smith

2018

Heliyon

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“…While, the SLS design of piles has not been covered as much in the literature. Recently, several curve fitting methods have been recommended to characterize uncertainties for the SLS of foundations (Misra & Roberts, 2009;Uzielli & Mayne, 2011;Huffman et al, 2015Huffman et al, , 2016Reddy & Stuedlein, 2017;Tang & Phoon, 2018a, b, c;Tang et al, 2019;Wu & Xin, 2019;Jesswein and Liu, 2020). Among the different curve fitting methods, the hyperbolic function is the most popular formula used in the studies.…”

Section: List Of Tablesmentioning

confidence: 99%

Reliability-Based Design for Serviceability Limit State of Micropiles in Ontario Soils

Gelimforoush

2023

Preprint

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<p>This research is to develop a reliability-based design (RBD) for the serviceability limit state (SLS) of micropiles in Ontario soils according to international and national design codes. A database of 40 static tests conducted on full-scale micropiles is collected and applied in this study. First, a two-parameter hyperbolic model is used to curve fit the load-displacement curves of the micropiles. The hyperbolic parameters are identified through the least squares regression method. Second, the statistical properties including the mean value, standard deviation, and probability distributions of the model parameters are established. Copula theory is implemented to represent the dependence between the model parameters and influencing factors. Third, Monte Carlo simulations are applied to randomly generate the load-displacement curves of micropiles according to the hyperbolic model and the statistical properties of the model parameters. Last, a series of resistance factors are developed for RBD of SLS of micropiles in Ontario soils according to three design codes, including the American Association of State Highway and Transportation Officials, the National Building Code of Canada, and Canadian Highway Bridge Design Code.</p>

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“…The uncertainty of load and resistance are quantified separately and reasonably incorporated into the design process. Therefore, this reliability-based design approach will generally produce a more efficient and consistent design than the traditional factor of safety approach [1]. To achieve these goals, many researchers have been working to develop a reasonable way to implement the LRFD method in bridge substructure design and to determine appropriate resistance factors for different regional soil conditions [2, 3, 4, 5, 6, 7, 8, and 9].…”

Section: Introductionmentioning

confidence: 99%

Third Bosporus Bridge Aerodynamics: Sectional and Full-Aeroelastic Model Testing

Zasso

Belloli

Argentini

et al. 2015

Springer Tracts on Transportation and Traffic

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This paper presents reliability based analyses for calibration of resistance factor for axiallyloaded drilled shafts. A total of 16 cases of drilled shaft load test are available in Louisiana Department of Transportation and Development (LADOTD) archives. Only 11 out of the 16 cases meet the FHWA "0.05D" settlement criterion. Due to the limited number of available drilled shaft cases in Louisiana, additional cases were collected from the neighboring state, i.e. Mississippi, which has subsurface soil conditions similar to Louisiana soils in its drilled shaft load test database. 15 drilled shafts from Mississippi were finally selected from 50 available cases based on selection criteria of subsurface soil conditions and final settlement. As a result, a database of 26 drilled shafts representing the typical design practice in Louisiana was created for statistical reliability analysis. Predictions of load-settlement behavior of drilled shafts from soil borings were determined using FHWA design method (O'Neill and Reese method) via SHAFT computer program. Measured drilled shaft axial nominal resistance was determined from either the Osterberg cell (O-cell) test or the conventional top-down static load test. Statistical analyses were performed to compare the predicted total drilled shaft nominal axial resistance and the measured nominal resistance. Results show that the selected design method underestimates the measured drilled shaft resistance by an average of 35%. The Monte Carlo simulation method was selected to perform the LRFD calibration under strength I limit state. Total resistance factors for different reliability indexes () were determined and compared with those in literature. LRFD calibration showed that the FHWA design method has a resistance factor () of 0.40 at the target reliability index (T) of 3.0. . Results show that the selected design method underestimates the measured drilled shaft resistance by an average of 35%. The Monte Carlo simulation method was selected to perform the LRFD calibration under strength I limit state. Total resistance factors for different reliability indexes () were determined and compared with those in literature. LRFD calibration showed that the FHWA design method has a resistance factor ) of 0.40 at the target reliability index (T) of 3.0.

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Service limit state resistance factors for drilled shafts

Cited by 26 publications

References 17 publications

Probabilistic analysis and resistance factor calibration for deep foundation design using Monte Carlo simulation

Probabilistic analysis and resistance factor calibration for deep foundation design using Monte Carlo simulation

Reliability-Based Design for Serviceability Limit State of Micropiles in Ontario Soils

Third Bosporus Bridge Aerodynamics: Sectional and Full-Aeroelastic Model Testing

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