Safety factors and limit states analysis in geotechnical engineering

1984 ◽  
Vol 21 (1) ◽  
pp. 1-7 ◽  
Author(s):  
G. G. Meyerhof
Keyword(s):  
Geotechnical Engineering ◽  
Stability Conditions ◽  
Safety Factors ◽  
Limit States ◽  
Resistance Factors ◽  
Performance Factors ◽  
Load Factors ◽  
Partial Safety Factors ◽  
And Performance ◽  
Earth Retaining Structures

This paper outlines the ultimate and serviceability limit states in geotechnical engineering analyses. The magnitude of customary total and suggested partial safety factors in earthworks, earth retaining structures, excavations, and foundations is discussed. On the basis of comparisons between these safety factors and using recommended load factors on various types of loading, including water pressures, common resistance factors on cohesion and friction of soils and performance factors can be established together with some additional modification factors for particular stability conditions. The serviceability limit states of foundations and structures are briefly discussed.

Load and Resistance Factors for Progressive Collapse Resistance Design of Reinforced Concrete Building Structures

2011 ◽  
Vol 255-260 ◽  
pp. 338-344 ◽  
Author(s):  
Ying Wang ◽  
Feng Lin ◽  
Xiang Lin Gu
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Building Structures ◽  
Safety Factors ◽  
Ultimate State ◽  
Resistance Factors ◽  
Collapse Resistance ◽  
Load And Resistance Factors ◽  
Load Effects ◽  
Partial Safety Factors

Due to the absence of provision for the load and resistance factors in design codes in China, designers often quote the provisions which are given in criterion or guidance of other countries such as USA. However, the partial safety factors of the load are various in different criterions. Based on the reliability theory, the load and resistance factors for progressive collapse resistance design of building structures were determined in this study. Firstly the simplified format of design expression in the ultimate state was obtained according to the expression in routine structural design. Then the failure probability of a structure during design reference period was taken as the sum of the probability of all incompatible failure events in this period, and the objective reliability index of the structure could be obtained. Finally using trial-and-error procedure and JC method, reliability analysis was performed for structural members to obtain the partial safety factors of load effects and resistance and the coefficient for combination value of load effects in design expression in the ultimate state. In this paper the load and resistance factors for progressive collapse resistance design of reinforced concrete structures subjected to blast was calculated as an example, and the recommendation values were given for the application at last.

scholarly journals German Proposals for the Revision of Eurocode 7 “Geotechnical design”

2016 ◽  
Author(s):  
Markus Braun ◽  
Bernd Schuppener ◽  
Thomas Richter ◽  
Franz Ruppert ◽  
Martin Ziegler
Keyword(s):  
Human Error ◽  
First Generation ◽  
Safety Factors ◽  
Limit States ◽  
Eurocode 7 ◽  
Geotechnical Design ◽  
Partial Safety Factors ◽  
Structural Engineers ◽  
User Friendly ◽  
New Formula

After implementing the Eurocodes, concerns were raised that the set of rules and regulations is not suitable for the designer’s day-to-day use. The first generation of Eurocodes consists of 58 codes with more than 5,200 pages. Moreover, practitioners have to cope with national supplementary codes. As a result, an “Initiative on Improving the Practicability of Technical Rules for Building Constructions” (PRB) was established by the German construction industry and associations of structural engineers in 2011. As part of the initiative, a Project Group for Geotechnical Design was established alongside groups for the other Eurocodes, with the aim of streamlining Eurocode 7 and reducing the number of design approaches and partial safety factors. The paper will analyse the shortcomings of the two parts of Eurocode 7 and present a concept for a more concise and user-friendly code. Furthermore, comparative calculations have been performed for standard geotechnical design applications to investigate the potential for European harmonization in geotechnical design. The results are described and it is shown how they can be incorporated in the revision of EC 7. Moreover, a new formula for verifying geotechnical ultimate limit states is presented which formally covers all design approaches and also enables other parameters such as consequence classes, human error etc. to be incorporated by applying different multiplicative partial safety factors.

Verification and calibration studies for the new CAN/CSA-S472 foundations of offshore structures

1993 ◽  
Vol 30 (3) ◽  
pp. 515-525 ◽  
Author(s):  
K. Been ◽  
J.I. Clark ◽  
W.R. Livingstone
Keyword(s):  
Offshore Structures ◽  
Technical Committee ◽  
Performance Standard ◽  
Safety Factors ◽  
Offshore Structure ◽  
Limit States ◽  
Resistance Factors ◽  
Development Of Resistance ◽  
System A ◽  
Load And Resistance Factors

In June 1992, the Canadian Standards Association (CSA) published a code for the design, construction, and installation of fixed offshore structures. This code is relatively advanced in its application of limit states design to offshore structures. The part dealing with foundations is written as a performance standard. It does not specify resistance factors (or safety factors) to achieve the target reliability of the structure. Although limit states design is common practice among geotechnical engineers, the application of resistance factors is a problem. This paper describes some of the studies and conclusions reached by the Technical Committee in the development of the CSA foundations standard. As a first step, resistance factors were developed by calibration to conventional total factors of safety for the failure mechanisms considered. This approach has severe limitations. In particular, the applicability of safety factors developed for onshore practice or other offshore areas to the ice-dominated environment of Canadian offshore regions is questionable. In addition, many offshore structure designs include consideration of dynamic loading and scour or erosion problems that cannot be satisfactorily dealt with using factors of safety. An example of the problem of applying separate load and resistance factors for a bearing-capacity problem is given to show that load and resistance are not independent of each other. Because of the problems with development of resistance factors, the CSA foundations standard dictates that offshore structure designs include a risk analysis of the foundation system. A simple form of such an analysis for a caisson-retained sand structure is included in the paper. Key words : offshore structures, foundations, standard, safety, limit states design.

Resistance factors for steel highway bridges

1984 ◽  
Vol 11 (2) ◽  
pp. 324-334 ◽  
Author(s):  
D. J. Laurie Kennedy ◽  
Karen A. Baker
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Highway Bridges ◽  
Limit States ◽  
Welded Steel ◽  
Mean Values ◽  
Resistance Factors ◽  
Performance Factors ◽  
Simulation Performance ◽  
Girder Bridges

Resistance (performance) factors for bridge members composed of rolled and welded steel sections are developed consistent with the live and dead load factors given in the Ontario Highway Bridge Design Code (OHBDC).Ratios of the load components of seven different spans of plate and box girder bridges are used with the statistical data for loads used in the development of the OHBDC. Monte Carlo simulation techniques are used to compose distribution curves for the various resistance functions from distribution curves describing the appropriate geometric properties, material properties, and test/predicted ratios. Using the 0.001 and 0.05 fractiles of the distribution curves so obtained for the resistances, mean values and coefficients of variation are obtained for equivalent lognormal distribution curves.Resistance factors are then developed for the fully plastic moment resistance, the yield moment, the inelastic buckling moment resistance, the elastic buckling moment resistance, the moment resistance of composite sections, and column resistances for slenderness parameter values of 0.8, 1.0, and 1.2. A general resistance factor of 0.93 is recommended for all the resistances and bridges studied. Resistance factors of 0.95 and 0.98 are considered appropriate for the flexural resistance of bridges composed of welded and rolled sections, respectively. Key words: bridges, limit states, Monte Carlo simulation, performance factors, resistance factors, steel, rolled sections, welded sections.

scholarly journals Comparison of Analysis Specifications and Practices for Diaphragm Wall Retaining System

2018 ◽  
Vol 40 (1) ◽  
pp. 21-29
Author(s):  
Anu James ◽  
Babu Kurian
Keyword(s):  
Deep Foundations ◽  
Foundation Engineering ◽  
Safety Factors ◽  
Finite Element Software ◽  
Codes Of Practice ◽  
Numerical Studies ◽  
Partial Safety Factors ◽  
Diaphragm Walls ◽  
Aashto Lrfd ◽  
Earth Retaining Structures

AbstractDiaphragm walls are deep embedded earth retaining structures. They also act as a part of the foundation. Geotechnical codes of practice from various countries provide procedures for the analysis of deep foundations. Not many standards are available that directly regulate the analysis of diaphragm walls. This paper compares the analysis of diaphragm walls performed using the foundation codes of different countries. Codes including EN 1997-1, BS 8002, BS 8004, BS EN 1538, AASHTO LRFD Bridge Design Specifications, AS 4678, AS 5100.3, Canadian Foundation Engineering Manual, CAN/CSA S6, IS 9556 and IS 4651 are chosen for the study. Numerical studies and calculations are done using the finite element software Plaxis 2d. Comparative study is performed based on the values of displacements and the forces developed. Study also evaluates the effect of differences in partial safety factors. The outcome of research emphasises the need for development of comprehensive analysis procedures.

Limit states and reliability-based design for a non-codified problem of aqueduct buoyancy

2006 ◽  
Vol 43 (8) ◽  
pp. 869-883
Author(s):  
Gil Robinson ◽  
James Graham ◽  
Ken Skaftfeld ◽  
Ron Sorokowski
Keyword(s):  
Design Methods ◽  
Model Parameters ◽  
Safety Factors ◽  
Design Code ◽  
Limit States ◽  
Reliability Based Design ◽  
Simulation Techniques ◽  
Working Stress ◽  
Engineering Problems ◽  
Partial Safety Factors

Limit states design methods and engineering judgement have been used to assess buoyancy issues for remediation of the 85 year old Shoal Lake Aqueduct in Manitoba. The study demonstrates how these methods can be applied to non-codified engineering problems. Four separate buoyancy analyses were completed using (i) partial safety factors from the Ontario Highway Bridge Design Code, (ii) project-specific partial safety factors, (iii) Monte Carlo simulation techniques, and (iv) working stress design (WSD) methods. Engineering judgement was required to develop a buoyancy model, interpret data for modeling parameters, and provide meaningful values for parameters that could not be measured. Results from the analyses show that more uniform reliability is provided when measured variability of the model parameters is accounted for. The reliability is not quantifiable when working stress design methods are used. Key words: limit states, probability, non-codified problem, aqueduct, buoyancy.

A Reliability-Based Approach for the Design of Nuclear Piping for Internal Pressure

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Kleio Avrithi ◽  
Bilal M. Ayyub
Keyword(s):  
Internal Pressure ◽  
Allowable Stress ◽  
Safety Factors ◽  
Limit States ◽  
Present Design ◽  
Partial Safety Factors ◽  
Factor Design ◽  
American Society ◽  
Load And Resistance Factor ◽  
Allowable Stress Design

Nuclear pipes are designed to withstand primary membrane stresses generated by internal pressure according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section III, Parts NB-3641, NC-3641, and ND-3641, which uses the allowable stress design (ASD) method. This paper presents limit states and equations for the design of nuclear pipes for internal pressure based on the load and resistance factor design (LRFD) method. The LRFD method is shown and explained to be more consistent than the ASD method. The paper presents the procedure for the derivation of the partial safety factors. Moreover, these factors are evaluated, example calculations are provided, and comparisons with the present design are made.

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