Development of Resistance Factors for Axial Capacity of Driven Piles in North Carolina
Development of Resistance Factors for Axial Capacity of Driven Piles in North Carolina

Author:

Publisher:

Published: 2002

Total Pages:

ISBN-13:

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Resistance factors were developed in the framework of reliability theory for the Load and Resistance Factor Design (LRFD) of driven pile's axial capacity in North Carolina utilizing pile load test data available from the North Carolina Department of Transportation. A total of 140 Pile Driving Analyzer (PDA) data and 35 static load test data were compiled and grouped into different design categories based on four pile types and two geologic regions. Resistance statistics were evaluated for each design category in terms of bias factors. Bayesian updating was employed to improve the statistics of the resistance bias factors, which were derived from a limited number of pile load test data. Load statistics presented in the current AASHTO LRFD Bridge Design Specifications were used in the reliability analysis and the calibration of the resistance factors. Reliability analysis of the current NCDOT practice of pile foundation design was performed to evaluate the level of safety and to select the target reliability indices. Resistance factor calibration was performed for the three methods of static pile capacity analysis commonly used in the NCDOT: the Vesic, the Nordlund, and the Meyerhof methods. Two types of First Order Reliability Methods (Mean Value First Order Second Moment method and Advanced First Order Second Moment method) were employed for the reliability analysis and the calibration of the resistance factors. Recommended resistance factors are presented for the three methods of static pile capacity analysis and for seven different design categories of pile types and geologic regions. The resistance factors developed and recommended from this research are specific for the pile foundation design by the three static capacity analysis methods and for the distinct soil type of the geologic regions of North Carolina. The methodology of the resistance factor calibration developed from this research can be applied to the resistance factor calibration for other foundation.

Load and Resistance Factor Design (LRFD) for Driven Piles Using Dynamic Methods--A Florida Perspective
Load and Resistance Factor Design (LRFD) for Driven Piles Using Dynamic Methods--A Florida Perspective

Author: MC. McVay

Publisher:

Published: 2000

Total Pages: 12

ISBN-13:

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The parameters for load and resistance factor design (LRFD) of driven piles using dynamic methods are presented based on a database of 218 pile cases in Florida. Eight dynamic methods were studied: ENR, modified ENR, FDOT, and Gates driving formulas, Case Analysis with Wave Analysis Program (CAPWAP), Case Method for Pile Driving Analyzer (PDA), Paikowsky's energy method, and Sakai's energy method. It was demonstrated that the modern methods based on wave mechanics, such as CAPWAP, PDA, and Paikowsky's energy methods, are roughly twice as cost effective to reach the target reliability indices of 2.0 to 2.5 (failure probability = 0.62 to 2.5%) as the ENR and modified ENR driving formulas. The Gates formula, when used separately on piles with Davisson capacities smaller or larger than 1779 kN, has an accuracy comparable to the modern methods. The utilizable measured Davisson capacity, defined as ?/? (ratio of resistance/mean capacity) obtained from testing at beginning of redrive (BOR), is only slightly larger than the end of drive (EOD) values. Furthermore, past practice with driving formulas reveals the existence of a large redundancy in pile groups against failure. The latter suggests the use of a lower relatively reliability target index, ?T = 2.0 (pf = 2.5%) for single pile design. Also, the utilizable measured Davisson capacity, ?/?, for all the dynamic methods studied, is quite similar to published values (Lai et al. 1995; Sidi 1985) for static estimates from in situ tests.

Development of Load and Resistance Factor Design for Ultimate and Serviceability Limit States of Transportation Structure Foundations
Development of Load and Resistance Factor Design for Ultimate and Serviceability Limit States of Transportation Structure Foundations

Author: Rodrigo Salgado

Publisher: Purdue University Press

Published: 2011-10-12

Total Pages: 76

ISBN-13: 9781622600076

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Most foundation solutions for transportation structures rely on deep foundations, often on pile foundations configured in a way most suitable to the problem at hand. Design of pile foundation solutions can best be pursued by clearly defining limit states and then configuring the piles in such a way as to prevent the attainment of these limit states. The present report develops methods for load and resistance factor design (LRFD) of piles, both nondisplacement and displacement piles, in sand and clay. With the exception of the method for design of displacement piles in sand, all the methods are based on rigorous theoretical mechanics solutions of the pile loading problem. In all cases, the uncertainty of the variables appearing in the problem and of the relationships linking these variables to the resistance calculated using these relationships are carefully assessed. Monte Carlo simulations using these relationships and the associated variabilities allow simulation of resistance minus load distributions and therefore probability of failure. The mean (or nominal) values of the variables can be adjusted so that the probability of failure can be made to match a target probability of failure. Since an infinite number of combinations of these means can be made to lead to the same target probability of failure, we have developed a way to determine the most likely ultimate limit state for a given probability of failure. Once the most likely ultimate limit state is determined, the values of loads and resistances for this limit state can be used, together with the values of the mean (or nominal) loads and resistances to calculate load and resistance factors. The last step in the process involves adjusting the resistance factors so that they are consistent with the load factors specified by AASHTO. Recommended resistance factors are then given together with the design methods for which they were developed.

Load and Resistance Factor Design and Construction Control of Driven Piles in Intermediate Geomaterials
Load and Resistance Factor Design and Construction Control of Driven Piles in Intermediate Geomaterials

Author: Pramila Adhikari

Publisher:

Published: 2019

Total Pages: 188

ISBN-13: 9781085629942

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Static Analysis methods originally developed for soils are currently used for estimating pile resistances in Intermediate Geomaterials (IGMs), and structural capacity has been considered as the limiting pile capacity on hard rocks. The application of current Load and Resistance Factor Design (LRFD) for piles in IGMs has resulted in relatively high uncertainties in pile resistance estimation during design and the length to which the piles are driven into IGMs during construction. Moreover, the absence of standard criteria to differentiate the geomaterials creates challenges in the design and construction of driven piles in IGMs. The application of a dynamic analysis method using Wave Equation Analysis Program is constrained by geomaterial input for IGMs and rocks. These current challenges have led to conservative pile resistance estimations. Thus, the overall objectives of this study were to determine efficient static analysis methods, dynamic procedures for construction control, pile setup/relaxation, and resistance factors for the estimation of the axial pile resistances in IGMs, ensuring a prescribed level of reliability to meet LRFD philosophy. To accomplish these objectives, classification criteria of geomaterials were first created to establish a standard quantitative delineation between the soils, IGMs, and hard rocks for the design of driven piles. In addition, a catalog of IGM properties was prepared to facilitate the preliminary design of piles in IGMs. Secondly, a new set of design equations were developed and validated for IGMs by utilizing the developed geomaterial classification criteria. Thirdly, wave equation analysis procedures for IGMs were recommended for pile construction control. Fourthly, changes in pile resistances in IGMs with respect to time at an End of Driving and Beginning of Restrike were assessed. Finally, probability based resistance factors were calibrated and recommended based on the efficiency factors for the existing and calibrated static analysis methods. Calibrated static analysis methods were concluded to have higher efficiency factors of 0.61, 0.30, and 0.41 against efficiency factors of 0.28, 0.09, and 0.14 corresponding to existing static analysis methods for shaft resistance estimation in IGMs. Similarly, calibrated static analysis methods were concluded to have higher efficiency factors of 0.24 and 0.48 against efficiency factors of 0.13 and 0.29 corresponding to existing static analysis methods for end bearing estimation in IGMs.

Load and Resistance Factor Design (LRFD) Pile Driving Project - Phase II Study
Load and Resistance Factor Design (LRFD) Pile Driving Project - Phase II Study

Author: Aaron S. Budge

Publisher:

Published: 2014

Total Pages: 514

ISBN-13:

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Driven piles are the most common foundation solution used in bridge construction (Paikowsky et al., 2004). Their safe use requires to reliable verification of their capacity and integrity. Dynamic analyses of driven piles are methods attempting to obtain the static capacity of a pile, utilizing its behavior during driving. Dynamic equations (aka pile driving formulas) are the earliest and simplest forms of dynamic analyses. The development and the examination of such equation tailored for MnDOT demands is presented. In phase I of the study reported by Paikowsky et al. (2009, databases were utilized to investigate previous MnDOT (and other) dynamic formulas and use object oriented programming for linear regression to develop a new formula that was then calibrated for LRFD methodology and evaluated for its performance. This report presents the findings of phase II of the study in which a comprehensive investigation of the Phase I findings were conducted. The studies lead to the development of dynamic formulae suitable for MnDOT foundation practices, its calibrated resistance factors and its application to concrete and timber piles. Phase II of the study also expanded on related issues associated with Wave Equation analyses and static load tests, assisting the MnDOT in establishing requirements and specifications.