Reliability-based load and resistance factors for soil-nail walls

2011 ◽  
Vol 48 (6) ◽  
pp. 915-930 ◽  
Author(s):  
G.L. Sivakumar Babu ◽  
Vikas Pratap Singh
Keyword(s):  
Limit Equilibrium ◽  
Limit State ◽  
Input Parameter ◽  
Limit States ◽  
Soil Nail ◽  
Resistance Factors ◽  
Strength Limit ◽  
Load And Resistance Factors ◽  
Load And Resistance Factor ◽  
Parameter Values

Existing soil nailing design methodologies are essentially based on limit equilibrium principles that together with a lumped factor of safety or a set of partial factors on the material parameters and loads account for uncertainties in design input parameter values. Recent trends in the development of design procedures for earth retaining structures are towards load and resistance factor design (LRFD). In the present study, a methodology for the use of LRFD in the context of soil-nail walls is proposed and a procedure to determine reliability-based load and resistance factors is illustrated for important strength limit states with reference to a 10 m high soil-nail wall. The need for separate partial factors for each limit state is highlighted, and the proposed factors are compared with those existing in the literature.

scholarly journals Reliability Estimation for Highway Bridges

2020 ◽  
Author(s):  
Nafiseh Kiani
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Limit State ◽  
Highway Bridges ◽  
Reliability Estimation ◽  
State Function ◽  
Limit States ◽  
Resistance Factors ◽  
Load And Resistance Factors ◽  
Reliability Methods

Structural reliability analysis is necessary to predict the uncertainties which may endanger the safety of structures during their lifetime. Structural uncertainties are associated with design, construction and operation stages. In design of structures, different limit states or failure functions are suggested to be considered by design specifications. Load and resistance factors are two essential parameters which have significant impact on evaluating the uncertainties. These load and resistance factors are commonly determined using structural reliability methods. The purpose of this study is to determine the reliability index for a typical highway bridge by considering the maximum moment generated by vehicle live loads on the bridge as a random variable. The limit state function was formulated and reliability index was determined using the First Order Reliability Methods (FORM) method.

Evaluation of peak side resistance for rock socketed shafts in weak sedimentary rock from an extensive database of published field load tests: a limit state approach

2019 ◽  
Vol 56 (12) ◽  
pp. 1816-1831 ◽  
Author(s):  
Pouyan Asem ◽  
Paolo Gardoni
Keyword(s):  
Test Data ◽  
Limit State ◽  
Deformation Modulus ◽  
Load Test ◽  
Resistance Factors ◽  
Strength Limit ◽  
Side Resistance ◽  
Load Tests ◽  
Load And Resistance Factor

This paper presents analyses of the measured peak side resistance of rock sockets constructed in weak claystone, shale, limestone, siltstone, and sandstone. The peak side resistance is obtained from in situ axial load tests on drilled shafts, anchors, and plugs. The parameters that affect the development of peak side resistance are determined using in situ load test data. It is found that peak side resistance increases with the unconfined compressive strength and deformation modulus of the weak rock, and decreases with the increase in length of the shear surface along the rock socket sidewalls. The increase in socket diameter also slightly decreases the peak side resistance. Additionally, it is found that the initial normal stresses do not significantly affect the measured peak side resistance in the in situ load tests. The in situ load test data are used to develop an empirical design equation for determination of the peak side resistance. The proposed model for peak side resistance and the reliability analysis are used to determine the corresponding resistance factors for use in the load and resistance factor design framework for assessment of the strength limit state.

Consequence factors in the ultimate limit state design of shallow foundations

2011 ◽  
Vol 48 (2) ◽  
pp. 265-279 ◽  
Author(s):  
Gordon A. Fenton ◽  
D. V. Griffiths ◽  
Olaide O. Ojomo
Keyword(s):  
Limit State ◽  
Shallow Foundations ◽  
Resistance Factor ◽  
Shallow Foundation ◽  
Ultimate Limit State ◽  
Resistance Factors ◽  
Limit State Design ◽  
Reliability Based Design ◽  
Load And Resistance Factors ◽  
Load And Resistance Factor

The reliability-based design of shallow foundations is generally implemented via a load and resistance factor design methodology embedded in a limit state design framework. For any particular limit state, the design proceeds by ensuring that the factored resistance equals or exceeds the factored load effects. Load and resistance factors are determined to ensure that the resulting design is sufficiently safe. Load factors are typically prescribed in structural codes and take into account load uncertainty. Factors applied to resistance depend on both uncertainty in the resistance (accounted for by a resistance factor) and desired target reliability (accounted for by a newly introduced consequence factor). This paper concentrates on how the consequence factor can be defined and specified to adjust the target reliability of a shallow foundation designed to resist bearing capacity failure.

Calibration concepts for load and resistance factor design (LRFD) of reinforced soil walls

2008 ◽  
Vol 45 (10) ◽  
pp. 1377-1392 ◽  
Author(s):  
Richard J. Bathurst ◽  
Tony M. Allen ◽  
Andrzej S. Nowak
Keyword(s):  
Limit State ◽  
Reinforced Soil ◽  
Resistance Factor ◽  
Resistance Factors ◽  
Soil Walls ◽  
Calibration Methods ◽  
Load And Resistance Factors ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Reinforced Soil Walls

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 issues related to the influence of outliers in the datasets and possible dependencies between variables that can have an important influence on the results of calibration.

Reliability analysis of wood I-joists

1993 ◽  
Vol 20 (4) ◽  
pp. 564-573 ◽  
Author(s):  
R. O. Foschi ◽  
F. Z. Yao
Keyword(s):  
Reliability Analysis ◽  
Carrying Capacity ◽  
Failure Modes ◽  
Limit State ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Element Analysis ◽  
Strength Limit ◽  
Reliability Method ◽  
Load Carrying

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs. Key words: reliability, limit state design, wood composites, I-joist, structural analysis.

scholarly journals Load and resistance factor design of drilled shafts subjected to lateral loading at service limit state

2018 ◽  
Author(s):  
◽  
Minh Dinh Uong
Keyword(s):  
Limit State ◽  
Design Procedure ◽  
Drilled Shafts ◽  
Resistance Factor ◽  
Lateral Loading ◽  
Drilled Shaft ◽  
Resistance Factors ◽  
Service Limit State ◽  
Load And Resistance Factor ◽  
Aashto Lrfd

Since 2007, the American Association of State Highway Administration Officials (AASHTO) has made utilization of Load and Resistance Factor Design (LRFD) mandatory on all federally-funded new bridge projects (AASHTO, 2007). However, currently, there are no guidelines implementing LRFD techniques for design of drilled shaft subjected to lateral loads using reliability-based analysis. On a national level, the AASHTO LRFD Bridge Design Specifications (AASHTO, 2012) specify that a resistance factor of 1.0 be used for design of drilled shafts subjected to lateral loading at service limit state, which means reliability-based analyses for calibration of resistance factors have not been performed. Therefore, there is a need to create a LRFD procedure for drilled shafts subjected to lateral loading at service limit state that has reliability-based calibrated resistance factors applicable for future projects. The research focuses on the reliability-based analysis of drilled shaft subjected to lateral loading, characterize lateral load transfer model of drilled shafts in shale, probabilistic calibrate resistance factor and contribute to the development of design procedure using LRFD. The objective of this work is to improve the design of drilled shaft subjected to lateral loading using LRFD at service limit state by providing a more reliable design procedure than the current AASHTO LRFD procedure for drilled shafts subjected to lateral loading at service limit state.

scholarly journals Calibration of Load and Resistance Factors for Breakwater Foundation Design. Application on Different Types of Superstructures

2021 ◽  
Vol 33 (6) ◽  
pp. 287-292
Author(s):  
Jungwon Huh ◽  
Nhu Son Doan ◽  
Van Ha Mac ◽  
Van Phu Dang ◽  
Dong Hyawn Kim
Keyword(s):  
Wave Loading ◽  
Efficient Design ◽  
Foundation Design ◽  
Resistance Factors ◽  
Different Types ◽  
Load And Resistance Factors ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Perforated Caisson ◽  
Rubble Mound Breakwaters

Load and resistance factor design is an efficient design approach that provides a system of consistent design solutions. This study aims to determine the load and resistance factors needed for the design of breakwater foundations within a probabilistic framework. In the study, four typical types of Korean breakwaters, namely, rubble mound breakwaters, vertical composite caisson breakwaters, perforated caisson breakwaters, and horizontal composite breakwaters, are investigated. The bearing capacity of breakwater foundations under wave loading conditions is thoroughly examined. Two levels of the target reliability index (RI) of 2.5 and 3.0 are selected to implement the load and resistance factors calibration using Monte Carlo simulations with 100,000 cycles. The normalized resistance factors are found to be lower for the higher target RI as expected. Their ranges are from 0.668 to 0.687 for the target RI of 2.5 and from 0.576 to 0.634 for the target RI of 3.0.

scholarly journals Load and resistance factors for earth retaining, reinforced concrete hydraulic structures based on a reliability index (β) derived from the Probability of Unsatisfactory Performance (PUP) : phase 2 study

2021 ◽  
Author(s):  
Robert Ebeling ◽  
Barry White
Keyword(s):  
Reinforced Concrete ◽  
Hydraulic Structure ◽  
Limit State ◽  
Hydraulic Structures ◽  
Army Corps ◽  
Second Phase ◽  
Limit States ◽  
Two Phase ◽  
Topic Area ◽  
Load And Resistance Factor

This technical report documents the second of a two-phase research and development (R&D) study in support of the development of a combined Load and Resistance Factor Design (LRFD) methodology that accommodates geotechnical as well as structural design limit states for design of the U.S. Army Corps of Engineers (USACE) reinforced concrete, hydraulic navigation structures. To this end, this R&D effort extends reliability procedures that have been developed for other non-USACE structural systems to encompass USACE hydraulic structures. Many of these reinforced concrete, hydraulic structures are founded on and/or retain earth or are buttressed by an earthen feature. Consequently, the design of many of these hydraulic structures involves significant soil structure interaction. Development of the required reliability and corresponding LRFD procedures has been lagging in the geotechnical topic area as compared to those for structural limit state considerations and have therefore been the focus of this second-phase R&D effort. Design of an example T-Wall hydraulic structure involves consideration of five geotechnical and structural limit states. New numerical procedures have been developed for precise multiple limit state reliability calculations and for complete LRFD analysis of this example T-Wall reinforced concrete, hydraulic structure.

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