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.

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.

ISSC Technical Committee I.1 Environment

2007 ◽  
Author(s):  
Bruce L. Hutchison
Keyword(s):  
Climate Change ◽  
Marine Environment ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Technical Committee ◽  
Environmental Data ◽  
Offshore Structure ◽  
Parametric Roll ◽  
Modeling And Analysis ◽  
The Past

This paper presents highlights of the report of the 16th International Ship and Offshore Structure Congress (ISSC) I.1 Environment Committee presented in August 2006 in Southampton, UK. Subjects addressed include notable accomplishments in the study of the marine environment pertinent to the design and operation of ships and offshore structures. These include advances in the past three years with respect to sensing, modeling and analysis of environmental data, discussion of rogue waves, climate change and parametric roll, and recommendations for further research.

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.

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.

scholarly journals A Study on the Holding Capacity Safety Factors for Torpedo Anchors

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Luís V. S. Sagrilo ◽  
José Renato M. de Sousa ◽  
Edison C. P. Lima ◽  
Elisabeth C. Porto ◽  
Jane V. V. Fernandes
Keyword(s):  
Finite Element ◽  
Experimental Tests ◽  
Structural Safety ◽  
Safety Factors ◽  
Resistance Factors ◽  
Numerical Predictions ◽  
Load And Resistance Factors ◽  
Capacity Calculation ◽  
Offshore Oil Industry ◽  
Offshore Oil

The use of powerful numerical tools based on the finite-element method has been improving the prediction of the holding capacity of fixed anchors employed by the offshore oil industry. One of the main achievements of these tools is the reduction of the uncertainty related to the holding capacity calculation of these anchors. Therefore, it is also possible to reduce the values of the associated design safety factors, which have been calibrated relying on models with higher uncertainty, without impairing the original level of structural safety. This paper presents a study on the calibration of reliability-based safety factors for the design of torpedo anchors considering the statistical model uncertainty evaluated using results from experimental tests and their correspondent finite-element-based numerical predictions. Both working stress design (WSD) and load and resistance factors design (LRFD) design methodologies are investigated. Considering the WSD design methodology, the single safety is considerably lower than the value typically employed in the design of torpedo anchors. Moreover, a LRFD design code format for torpedo anchors is more appropriate since it leads to designs having less-scattered safety levels around the target value.

Calibration of the Ontario Bridge Design Code 1983 edition

1984 ◽  
Vol 11 (4) ◽  
pp. 760-770 ◽  
Author(s):  
Hid N. Grouni ◽  
Andrzej S. Nowak
Keyword(s):  
Reliability Index ◽  
Calibration Procedure ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Safety Level ◽  
Acceptance Criterion ◽  
Resistance Factors ◽  
Concrete Girders ◽  
Load And Resistance Factors

The paper summarizes the calibration procedure used to calculate load and resistance factors for the Ontario Bridge Design Code 1983 edition. The limit states considered include serviceability and ultimate limit states during service and in construction. The acceptance criterion is closeness to a predetermined target safety level. Safety is measured in terms of a reliability index. The results of calibration are discussed for composite steel–concrete girders, pretensioned concrete girders, post-tensioned concrete decks, and timber decks. The analysis of construction design criteria is demonstrated on segmental bridges. Key words: code calibration, bridges, reliability index, load and resistance factors, limit states.

A reliability assessment of tubular joint specifications

1988 ◽  
Vol 15 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Jeffrey A. Packer ◽  
John S. M. Kremer
Keyword(s):  
Reliability Analysis ◽  
Offshore Structures ◽  
Structural Safety ◽  
Limit States ◽  
Load Effect ◽  
Hollow Section ◽  
Resistance Factors ◽  
Rational Development ◽  
Design Documents ◽  
Circular Hollow Section

The limit states design of structural components involves the use of resistance factors which account for the variabilities and uncertainties which exist in both load effect and element resistance. In this paper, the rational development of such resistance factors is examined for axially loaded K, T, and Y joints between steel circular hollow section members subject to predominantly static loading. The development of these factors is primarily oriented to the design of such joints in offshore structures under extreme environmental loading conditions, but onshore applications to buildings are also considered. A level II method of reliability analysis has been used for the derivation of the resistance factors. The joint strength criteria from seven prominent code and noncode design documents have been considered, and recommendations for resistance factors to be used in the design of offshore and onshore tubular joints are made. Key words: steel, offshore structures, tubes, joints, reliability analysis, structural safety.

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.

Development of geotechnical limit state design

1995 ◽  
Vol 32 (1) ◽  
pp. 128-136 ◽  
Author(s):  
Geoffrey G. Meyerhof
Keyword(s):  
Limit State ◽  
Offshore Structures ◽  
Soil Parameters ◽  
Ultimate Limit State ◽  
Offshore Structure ◽  
Limit States ◽  
Limit State Design ◽  
Earth Structures ◽  
Earth Retaining Structures ◽  
Operational Constraints

The historical development of limit state design in geotechnical engineering is reviewed. Total and partial factors of safety used for the design of land–based and offshore structures are compared. It is found that the factors of safety in different codes for the ultimate and serviceability limit states design of earthworks, earth retaining structures, and land-based and offshore foundations are very similar. Partial factors in the ultimate limit state design are linked to the variability of the loads and soil parameters, the design approximations, and construction tolerances. They influence the nominal probability of failure of the type of structure considered and the seriousness of failure, which differ for land-based and offshore structures. These probabilities are compared with human fatality risks of common experiences. The serviceability limit states are governed by structural and operational constraints and the intended service life of the land-based or offshore structure. The corresponding partial factors are generally taken as unity. Key words : codes, earth structures, foundations, human risks, limit states design, probability of failures, factors of safety.

Limit states design of concrete slender columns

1987 ◽  
Vol 14 (4) ◽  
pp. 439-446 ◽  
Author(s):  
S. A. Mirza ◽  
J. G. MacGregor
Keyword(s):  
Structural Design ◽  
Current Knowledge ◽  
Building Code ◽  
Limit States ◽  
Resistance Factors ◽  
Development Of Resistance ◽  
Load Factors ◽  
Building Load ◽  
The Moment ◽  
Slender Columns

The limit states design requires the use of load factors and resistance factors to consider the probability of overloading, understrength, or both. Research has been underway in Canada to introduce the probability-based limit states design for concrete structures. Based on the current knowledge of building load statistics, the National Building Code of Canada adopted a set of load factors which are different from those used in the Canadian Standards Association Standard A23.3-M77. This required the development of resistance factors that would be compatible with the load factors specified in the National Building Code of Canada. The research reported herein discusses the development of such resistance factors for use in computing the moment magnification of concrete slender columns. Key words: building codes, load factors, loads (forces), moment magnification, reinforced concrete, resistance, resistance factors, slender columns, stability, structural design.

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