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Tony M Allen - One of the best experts on this subject based on the ideXlab platform.
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load and resistance Factor Design lrfd calibration for steel grid reinforced soil walls
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2011Co-Authors: Richard J Bathurst, Bingquan Huang, Tony M AllenAbstract:This paper reports the results of load and resistance Factor Design (LRFD) calibration for pullout and yield limit states for steel grid reinforced soil walls owing to soil self-weight loading plus permanent uniform surcharge. The calibration method uses bias statistics to account for prediction accuracy of the underlying deterministic models for reinforcement load, pullout capacity and yield strength of the steel grids, and random variability in input parameters. A new revised pullout Design model is proposed to improve pullout resistance prediction accuracy and to remove hidden dependency with calculated pullout resistance values. Load and resistance Factors are proposed that give a uniform probability of failure of 1% for both pullout and yield limit states. The approach adopted in this paper has application to a wide variety of other reinforced soil wall technologies.
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calibration concepts for load and resistance Factor Design lrfd of reinforced soil walls
Canadian Geotechnical Journal, 2008Co-Authors: Andrzej S. Nowak, Tony M Allen, Richard J BathurstAbstract:Reliability-based Design concepts and their application to load and resistance Factor Design (LRFD or limit states Design (LSD) in Canada) are well known, and their adoption in geotechnical engineering Design is now recommended for many soil–structure interaction problems. Two important challenges for acceptance of LRFD for the Design of reinforced soil walls are (i) a proper understanding of the calibration methods used to arrive at load and resistance Factors, and (ii) the proper interpretation of the data required to carry out this process. This paper presents LRFD calibration principles and traces the steps required to arrive at load and resistance Factors using closed-form solutions for one typical limit state, namely pullout of steel reinforcement elements in the anchorage zone of a reinforced soil wall. A unique feature of this paper is that measured load and resistance values from a database of case histories are used to develop the statistical parameters in the examples. The paper also addresses ...
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development of new pile driving formula and its calibration for load and resistance Factor Design
Transportation Research Record, 2007Co-Authors: Tony M AllenAbstract:Before 1997, the Washington State Department of Transportation (WSDOT) used the Engineering News (EN) formula for driving piling to Design capacity. WSDOT-sponsored research published in 1988 had shown that the EN formula was quite inaccurate and that adopting the Gates formula would be a substantial improvement. In 1996, an in-house study was initiated to identify or develop a new driving formula to be used for routine pile-driving acceptance in the WSDOT standard specifications. Recently, compiled databases of pile load test results were used as the basis for developing improvements to the Gates formula to improve the prediction accuracy of pile-bearing resistance. From this empirical analysis, the WSDOT driving formula was derived. Once the WSDOT driving formula had been developed, the empirical data used for its development were also used to establish statistics that could be used in reliability analyses to determine resistance Factors for load and resistance Factor Design. The Monte Carlo method was ...
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development of new pile driving formula and its calibration for load and resistance Factor Design
Transportation Research Record, 2007Co-Authors: Tony M AllenAbstract:Before 1997, the Washington State Department of Transportation (WSDOT) used the Engineering News (EN) formula for driving piling to Design capacity. WSDOT-sponsored research published in 1988 had shown that the EN formula was quite inaccurate and that adopting the Gates formula would be a substantial improvement. In 1996, an in-house study was initiated to identify or develop a new driving formula to be used for routine pile-driving acceptance in the WSDOT standard specifications. Recently, compiled databases of pile load test results were used as the basis for developing improvements to the Gates formula to improve the prediction accuracy of pile-bearing resistance. From this empirical analysis, the WSDOT driving formula was derived. Once the WSDOT driving formula had been developed, the empirical data used for its development were also used to establish statistics that could be used in reliability analyses to determine resistance Factors for load and resistance Factor Design. The Monte Carlo method was ...
Andrzej S. Nowak - One of the best experts on this subject based on the ideXlab platform.
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calibration concepts for load and resistance Factor Design lrfd of reinforced soil walls
Canadian Geotechnical Journal, 2008Co-Authors: Andrzej S. Nowak, Tony M Allen, Richard J BathurstAbstract:Reliability-based Design concepts and their application to load and resistance Factor Design (LRFD or limit states Design (LSD) in Canada) are well known, and their adoption in geotechnical engineering Design is now recommended for many soil–structure interaction problems. Two important challenges for acceptance of LRFD for the Design of reinforced soil walls are (i) a proper understanding of the calibration methods used to arrive at load and resistance Factors, and (ii) the proper interpretation of the data required to carry out this process. This paper presents LRFD calibration principles and traces the steps required to arrive at load and resistance Factors using closed-form solutions for one typical limit state, namely pullout of steel reinforcement elements in the anchorage zone of a reinforced soil wall. A unique feature of this paper is that measured load and resistance values from a database of case histories are used to develop the statistical parameters in the examples. The paper also addresses ...
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Reliability-Based Criteria for Load and Resistance Factor Design Code for Wood Bridges
Transportation Research Record, 2000Co-Authors: Christopher D. Eamon, Michael A. Ritter, Andrzej S. Nowak, Joseph F. MurphyAbstract:Recently AASHTO adopted a load and resistance Factor Design code for highway bridges. The new code provides a rational basis for the Design of steel and concrete structures. However, the calibration was not done for wood bridges. Therefore, there is a need to fill this gap. The development of statistical models for wood bridge structures is discussed. Recent test results provided a considerable amount of new data for sawed wood and glulam components. Statistical methods provide a good tool for development of rational models for loads and resistance. Because of the random nature of load and resistance, reliability is a convenient measure of structural performance that also provides a rational basis for comparison of wood and other structural materials. The results of a recent project that led to development of rational Design criteria for wood bridges are presented. The structural reliability of selected wooden bridges Designed by the AASHTO codes are determined, and inadequacies in load distribution and m...
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LOAD AND RESISTANCE Factor Design CODE FOR WOOD BRIDGES
1995Co-Authors: Andrzej S. Nowak, Michael A. RitterAbstract:The development of a load and resistance Factor Design (LRFD) edition of AASHTO's Standard Specifications for Highway Bridges is complete. A part of this effort involved the development of LRFD provisions for wood bridges. These new specifications include numerous changes and several significant departures from current allowable stress Design practices for wood bridges. The live load model is based on the statistical analysis of the actual traffic data. The Design load is a superposition of the traditional HS20 truck and lane loading. Dynamic load is applied to wooden components of the superstructure. Strength of material is based on the nominal values derived from in-grade tests, specified for wet-use conditions and 2-month live load duration. The resistance Factors are determined consistently for all the limit states considered. The major changes in the approach to summarize the Design provisions are presented.
Joseph F. Murphy - One of the best experts on this subject based on the ideXlab platform.
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Reliability-Based Criteria for Load and Resistance Factor Design Code for Wood Bridges
Transportation Research Record, 2000Co-Authors: Christopher D. Eamon, Michael A. Ritter, Andrzej S. Nowak, Joseph F. MurphyAbstract:Recently AASHTO adopted a load and resistance Factor Design code for highway bridges. The new code provides a rational basis for the Design of steel and concrete structures. However, the calibration was not done for wood bridges. Therefore, there is a need to fill this gap. The development of statistical models for wood bridge structures is discussed. Recent test results provided a considerable amount of new data for sawed wood and glulam components. Statistical methods provide a good tool for development of rational models for loads and resistance. Because of the random nature of load and resistance, reliability is a convenient measure of structural performance that also provides a rational basis for comparison of wood and other structural materials. The results of a recent project that led to development of rational Design criteria for wood bridges are presented. The structural reliability of selected wooden bridges Designed by the AASHTO codes are determined, and inadequacies in load distribution and m...
Sri Sritharan - One of the best experts on this subject based on the ideXlab platform.
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A procedure for incorporating setup into load and resistance Factor Design of driven piles
Acta Geotechnica, 2016Co-Authors: Kam W Ng, Sri SritharanAbstract:In a recent study, the time-dependent increase in axial load resistance of steel H-piles driven into cohesive soils, due to setup, was systematically quantified using measured field data. A method to estimate the setup based on measurable soil properties was subsequently established. These studies highlighted that the uncertainties of the measurements of soil properties and thus the semi-empirical approach to estimate setup are significantly different from those of the methodology used for measuring the pile resistance during retaps at any time after the end of driving. Recognizing that the two sets of uncertainties should be addressed concurrently, this paper presents a procedure for determining the Factored resistance of a pile with due consideration to setup in accordance with the load and resistance Factor Design that targets a specific reliability index. Using the first-order second-moment method, the suggested procedure not only provides a simplified approach to incorporate any form of setup in Design, but it also produces comparable results to the computationally intensive first-order reliability method. Incorporating setup in Design and construction control is further shown to reduce foundation costs and minimize retap requirements on piles, ultimately reducing the construction costs of pile foundations.
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integration of construction control and pile setup into load and resistance Factor Design of piles
Soils and Foundations, 2014Co-Authors: Kam W Ng, Sri SritharanAbstract:Abstract Regionally developed Load and Resistance Factor Design (LRFD) recommendations for bridge pile Designs are enhanced by integrating the construction control capability of dynamic analysis methods and the recently developed pile setup quantification method in the calibration process. Using a high quality, electronic Pile LOad Test (PILOT) database and 10 recently completed full-scale pile tests, resistance Factors were developed using a reliability theory for a locally calibrated static analysis method and two dynamic analysis methods: the Wave Equation Analysis Program (WEAP) and the CAse Pile Wave Analysis Program (CAPWAP). Pile Design efficiency was improved by minimizing the discrepancy between Design and field pile resistances through a proposed probability-based construction control method. The efficiency of bridge foundations was further increased by incorporating the economic advantages of pile setup into the LRFD recommendations. Compared with recommendations made by Paikowsky et al. (2004) , Canadian Engineering Society (2006) and American Association of State Highway and Transportation Officials (2003) , regionally-calibrated resistance Factors were improved.
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Verification of Recommended Load and Resistance Factor Design and Construction of Piles in Cohesive Soils
Transportation Research Record, 2012Co-Authors: Sri Sritharan, Kenneth F. Dunker, Danielle DeboerAbstract:To enhance regional Design and construction practices for driven piles, FHWA permitted the development of regional resistance Factors for the Design of foundation piles. By fitting allowable stress Design safety Factors to the load and resistance Factor Design (LRFD) framework, several state departments of transportation (DOTs), including the Iowa DOT, have adopted interim procedures. Subsequently, an LRFD procedure that incorporates setup was developed for piles in cohesive soils through comprehensive research in Iowa. The proposed LRFD procedure used an Iowa DOT in-house static analysis method and the wave equation analysis program for construction control. To verify the adequacy of the proposed procedure and investigate its economic implications, differences in pile Design between the interim and the proposed LRFD procedures were evaluated on the basis of independent data collected from more than 600 production steel H-piles driven in cohesive soils. This study concluded that the proposed LRFD procedur...
Richard J Bathurst - One of the best experts on this subject based on the ideXlab platform.
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calibration of resistance Factors for load and resistance Factor Design of internal limit states of soil nail walls
Journal of Geotechnical and Geoenvironmental Engineering, 2019Co-Authors: Peiyuan Lin, Richard J BathurstAbstract:AbstractA general approach for calibration of resistance Factors for load and resistance Factor Design (LRFD) of pullout and tensile failure internal limit states of soil nail walls is presented. T...
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load and resistance Factor Design lrfd calibration for steel grid reinforced soil walls
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2011Co-Authors: Richard J Bathurst, Bingquan Huang, Tony M AllenAbstract:This paper reports the results of load and resistance Factor Design (LRFD) calibration for pullout and yield limit states for steel grid reinforced soil walls owing to soil self-weight loading plus permanent uniform surcharge. The calibration method uses bias statistics to account for prediction accuracy of the underlying deterministic models for reinforcement load, pullout capacity and yield strength of the steel grids, and random variability in input parameters. A new revised pullout Design model is proposed to improve pullout resistance prediction accuracy and to remove hidden dependency with calculated pullout resistance values. Load and resistance Factors are proposed that give a uniform probability of failure of 1% for both pullout and yield limit states. The approach adopted in this paper has application to a wide variety of other reinforced soil wall technologies.
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calibration concepts for load and resistance Factor Design lrfd of reinforced soil walls
Canadian Geotechnical Journal, 2008Co-Authors: Andrzej S. Nowak, Tony M Allen, Richard J BathurstAbstract:Reliability-based Design concepts and their application to load and resistance Factor Design (LRFD or limit states Design (LSD) in Canada) are well known, and their adoption in geotechnical engineering Design is now recommended for many soil–structure interaction problems. Two important challenges for acceptance of LRFD for the Design of reinforced soil walls are (i) a proper understanding of the calibration methods used to arrive at load and resistance Factors, and (ii) the proper interpretation of the data required to carry out this process. This paper presents LRFD calibration principles and traces the steps required to arrive at load and resistance Factors using closed-form solutions for one typical limit state, namely pullout of steel reinforcement elements in the anchorage zone of a reinforced soil wall. A unique feature of this paper is that measured load and resistance values from a database of case histories are used to develop the statistical parameters in the examples. The paper also addresses ...
