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1、A Reference number ISO 2394:1998(E) INTERNATIONAL STANDARD ISO 2394 Second edition 1998-06-01 General principles on reliability for structures Principes gnraux de la fiabilit des constructions ISO 2394:1998(E) ISO 1998 All rights reserved. Unless otherwise specified, no part of this publication may
2、be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case postale 56 CH-1211 Genve 20 Switzerland Internetcentraliso.ch X.400c=ch; a=400n
3、et; p=iso; o=isocs; s=central Printed in Switzerland ii ContentsPage 1Scope1 2Definitions1 3Symbols5 4Requirements and concepts 6 4.1 Fundamental requirements.6 4.2 Reliability differentiation of structures7 4.3 Structural design8 4.4 Compliance.9 4.5 Durability and maintenance10 5Principles of limi
4、t states design.11 5.1 Limit states.11 5.2 Design.12 6Basic variables.13 6.1 General13 6.2 Actions14 6.3 Environmental influences .15 6.4 Properties of materials16 6.5 Geometrical quantities 16 7Models 16 7.1 General16 7.2 Types of models.17 7.3 Model uncertainties .20 7.4 Design based on experiment
5、al models .21 ISOISO 2394:1998(E) iii 8Principles of probability-based design21 8.1 General21 8.2 Systems reliability versus element reliability.22 8.3 Specified degrees of required reliability .23 8.4 Calculation of failure probabilities.23 8.5 Implementation of probability-based design24 9Partial
6、factors format.24 9.1 Design conditions and design values .24 9.2 Representative values of actions.26 9.3 Characteristic values of properties of materials including soils 26 9.4 Characteristic values of geometrical quantities.27 9.5 Load cases and load combinations.27 9.6 Action effects and resistan
7、ces.27 9.7 Verification for fatigue.28 9.8 Calibration28 10Assessment of existing structures 28 10.1 Relevant cases.28 10.2 Principles of assessment28 10.3 Basic variables.29 10.4 Investigation.29 10.5 Assessment in the case of damage.30 Annex A: Quality management and quality assurance.31 Annex B:
8、Examples of permanent, variable and accidental actions35 Annex C: Models for fatigue37 Annex D: Design based on experimental models40 Annex E: Principles of reliability-based design.50 Annex F: Combination of actions and estimation of action values62 Annex G: Example of a method of combination of ac
9、tions71 Annex H: Index of definitions73 ISO 2394:1998(E) ISO iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical co
10、mmittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with t
11、he International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the
12、member bodies casting a vote. International Standard ISO 2394 was prepared by Technical Committee ISO/TC 98, Bases for design of structures, Subcommittee SC 2, Reliability of structures. This second edition cancels and replaces the first edition (ISO 2394:1986), which has been technically revised. A
13、nnexes A to F of this International Standard are for information only. ISOISO 2394:1998(E) v Introduction This International Standard constitutes a common basis for defining design rules relevant to the construction and use of the wide majority of buildings and civil engineering works, whatever the
14、nature or combination of the materials used. However, their application to each type of material (concrete, steel, timber, masonry, etc.) will require specific adaptation to ensure a degree of reliability which, as far as possible, is consistent with the objectives of the code drafting committees fo
15、r each material. This International Standard is intended to serve as a basis for those committees responsible for the task of preparing national standards or codes of practice in accordance with the technical and economic conditions in a particular country, and which take into account the nature, ty
16、pe and conditions of use of the structure and the properties of the materials during its design working life. It will also provide a common basis for other International Standards (e.g. ENV 1991-1 EC1) dealing with load-bearing structures. Thus it has a conceptual character and it is of a fairly gen
17、eral nature. It is important to recognize that structural reliability is an overall concept comprising models for describing actions, design rules, reliability elements, structural response and resistance, workmanship, quality control procedures and national requirements, all of which are mutually d
18、ependent. The modification of one factor in isolation could therefore disturb the balance of reliability inherent in the overall concept. It is therefore important that the modification of any one factor should be accompanied by a study of the implications relating to the overall reliability concept
19、. INTERNATIONAL STANDARD ISOISO 2394:1998(E) 1 General principles on reliability for structures 1 Scope This International Standard specifies general principles for the verification of the reliability of structures subjected to known or foreseeable types of action. Reliability is considered in relat
20、ion to the performance of the structure throughout its design working life. The general principles are applicable to the design of complete structures (buildings, bridges, industrial structures, etc.), the structural elements making up the structure and the foundations. This International Standard i
21、s also applicable to the successive stages in construction, namely the fabrication of structural elements, the transport and handling of the structural elements, their erection and all work on site, as well as the use of the structure during its design working life, including maintenance and repair.
22、 To allow for the differences in design practice between different countries, the national standards or codes of practice may be simpler or more detailed in comparison with this International Standard. Generally the principles are also applicable to the structural appraisal of existing constructions
23、 or assessing changes of use. However in some respects this is associated with special aspects of the basic variables and calculation models. Such aspects are considered in clause 10. NOTE When this International Standard is applied in a particular country for the development of its standards, it is
24、 admissible not to use those clauses which are not in accordance with the regulations of that particular country. 2 Definitions For the purposes of this International Standard, the following definitions apply. NOTE An alphabetical index of the definitions is given in annex H. 2.1 General terms 2.1.1
25、 structure: Organized combination of connected parts designed to provide some measure of rigidity. 2.1.2 structural element: Physically distinguishable part of a structure. EXAMPLES: Column, beam, plate. 2.1.3 structural system: Load-bearing elements of a building or civil engineering works and the
26、way in which these elements function together. 2.1.4 compliance: Fulfilment of specified requirements. ISO 2394:1998(E) ISO 2 2.1.5 life cycle: Total period of time during which the planning, execution and use of a construction works takes place. The life cycle begins with identification of needs an
27、d ends with demolition. 2.2 Terms relating to design in general 2.2.1 design situation: Set of physical conditions representing a certain time interval for which the design demonstrates that relevant limit states are not exceeded. 2.2.2 persistent situation: Normal condition of use for the structure
28、, generally related to its design working life. NOTE “Normal use“ includes possible extreme loading conditions due to wind, snow, imposed loads, earthquakes in areas of high seismicity, etc. 2.2.3 transient situation: Provisional condition of use or exposure for the structure. EXAMPLE: During its co
29、nstruction or repair, which represents a time period much shorter than the design working life. 2.2.4 accidental situation: Exceptional condition of use or exposure for the structure. EXAMPLES: Flood, land slip, fire, explosion, impact or local failure, which represent in most cases a very short tim
30、e period (apart from situations where a local failure may remain undetected during a longer period). 2.2.5 serviceability: Ability of a structure or structural element to perform adequately for normal use under all expected actions. 2.2.6 failure: Insufficient load-bearing capacity or inadequate ser
31、viceability of a structure or structural element. 2.2.7 reliability: Ability of a structure or structural element to fulfil the specified requirements, including the working life, for which it has been designed. 2.2.8 reference period: A chosen period of time which is used as a basis for assessing v
32、alues of variable actions, time-dependent material properties, etc. 2.2.9 limit state: A state beyond which the structure no longer satisfies the design performance requirements. NOTE Limit states separate desired states (no failure) from undesired states (failure). 2.2.10 ultimate limit state: A st
33、ate associated with collapse, or with other similar forms of structural failure. NOTE This generally corresponds to the maximum load-carrying resistance of a structure or structural element but in some cases to the maximum applicable strain or deformation. 2.2.11 serviceability limit state: A state
34、which corresponds to conditions beyond which specified service requirements for a structure or structural element are no longer met. 2.2.12 irreversible limit state: A limit state which will remain permanently exceeded when the actions which caused the excess are removed. 2.2.13 reversible limit sta
35、te: A limit state which will not be exceeded when the actions which caused the excess are removed. 2.2.14 structural integrity (structural robustness) : Ability of a structure not to be damaged by events like fire, explosions, impact or consequences of human errors, to an extent disproportionate to
36、the original cause. 2.2.15 design working life: Assumed period for which a structure or a structural element is to be used for its intended purpose without major repair being necessary. 2.2.16 maintenance: Total set of activities performed during the design working life of a structure to enable it t
37、o fulfil the requirements for reliability. ISO ISO 2394:1998(E) 3 2.2.17 reliability class of structures: Class of structures or structural elements for which a particular specified degree of reliability is required. 2.2.18 basic variable: Part of a specified set of variables representing physical q
38、uantities which characterize actions and environmental influences, material properties including soil properties, and geometrical quantities. 2.2.19 primary basic variable: Variable whose value is of primary importance to the design results. 2.2.20 limit state function: A function g of the basic var
39、iables, which characterizes a limit state when g(X1, X2, Xn) = 0: g 0 identifies with the desired state and g 0. . . (2) identifies the desired state. In principle, the purpose of design calculations (or prototype testing) is to ensure an adequate degree of reliability. To verify this, calculations
40、are performed according to a chosen design format. In this International Standard two possible design formats are treated: a probabilistic format (clause 8), and a partial factors format (clause 9). The partial factors format is the format which is intended to be used for design calculations in norm
41、al cases. The probabilistic format may be convenient for special design problems and may be used for the calibration of partial factors. ISO ISO 2394:1998(E) 13 In addition to design calculations, detailing is an important part of the design procedure. Thus assumptions made in the calculation models
42、 must be incorporated in the workshop drawings, instructions, etc., by appropriate structural provisions and detailing. 5.2.2 Design situations Actions, environmental influences and, in many cases, the expected properties of a structure vary with time. These variations, which occur throughout the li
43、fe of the structure, should be considered by selected design situations, each one representing a certain time interval with associated hazards, conditions and relevant structural limit states. Separate reliability checking is required for each design situation with due regard to the different conseq
44、uences of failure. The design situations are classified as: persistent situations; transient situations; accidental situations. Persistent and transient situations are considered to act with certainty. Accidental situations by definition occur with a relatively low probability during the design work
45、ing life. Whether loads, such as snow loads, earthquakes, etc., are associated with other transient or accidental situations will depend on local conditions. 6 Basic variables 6.1 General The calculation model for each limit state considered should contain a specified set of basic variables, represe
46、nting physical quantities which characterize actions and environmental influences, material and soil properties, and geometrical quantities. If the uncertainty of a basic variable is judged to be important, e.g. by experience or by a sensitivity study, it shall be represented as a random variable. T
47、he uncertainties generally consist of a systematic part (bias) and a random part. The uncertainties are caused by: inherent random variability, which is the unpredictable variability in time or among the typical structures and geographical regions under consideration; insufficient data and/or imprec
48、ise knowledge. Random variables should be described by probability distributions, which often should be considered as conditional. In many cases these distributions are characterized by main parameters such as mean, standard deviation, skewness and coefficient of correlation in the case of multi-dim
49、ensional distribution. A probabilistic model should be based on a statistical analysis of available data. It is important to separate and identify the different statistical populations in order not to use erroneous types of distributions. The data should, when possible, be examined to eliminate measurement errors, scale effects, etc. Probabilistic models for basic variables can be used directly within the probabilistic format (see clause 8). Within the partial factors format, bas