Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
In accordance with the requirements of MOHURD Notice on Printing and Distributing the Development and Revision Plan of Engineering Construction Standards and Specifications in 2015 (JIAN BIAO [2014] No. 189), this standard is revised by the drafting team through extensive investigation, careful summarization of practical experience, reference to relevant international standards and foreign advanced standards and on the basis of widely solicited opinions.
The main technical contents of this standard are as follows: 1. General Provisions; 2. Terms and Symbols; 3. Basic Requirements; 4. Principle of Limit State Design; 5. Actions on Structures and Environmental Influences; 6. Properties of Materials and Geotechnics and Geometrical Quantities; 7. Structural Analysis and Design Assisted by Testing; 8. Method of Partial Factors Design.
The main technical contents of the revision of this standard are as follows: 1. Comprehensive coordination with the Unified Standard for Reliability Design of Engineering Structures (GB 50153-2008); 2. Adjustment of the setting level of the safety degree of the building structure, increasing of the value of the partial factors of related functions; and for the basic combination of the action, canceling of the combined functions of the original standard that played a controlling role when the permanent load effect is dominant; 3. Addition of the seismic design status, and introduction of the design concept of "No damage in small earthquake, repairable in medium earthquake and no failure in great earthquake" to the seismic design of building structure; 4. Improvement of the requirements on reliability assessment of existing structures; 5. Addition of relevant regulations on the overall stability design of the structure; 6. Addition of relevant regulations on design of limit state of structure durability.
The provision printed in bold type in this standard are compulsory and must be enforced strictly.
The Ministry of Housing and Urban-Rural Development of the People's Republic of China is in charge of the administration of this standard and the explanation of the compulsory provisions; China Academy of Building Research is responsible for the explanation of specific technical contents. During the process of implementing this code, the relevant opinions and advices, whenever necessary, can be posted or passed on to China Academy of Building Research (Address: No.30, North 3rd Ring East Road, Beijing, 100013, China).
Chief development organizations of this standard: China Academy of Building Research
Participating development organizations: China Northeast Architecture Design and Research Institute Co., Ltd., Chongqing University, Central-South Architectural Design Institute Co., Ltd., China Southwest Architectural Design and Research Institute Co., Ltd.,
Dalian University of Technology, Zhejiang University and National Center for Quality Supervision and Test of Building Engineering
Chief drafting staff of this standard: Shi Zhihua, Xiao Congzhen, Chen Kai, Zhu Aiping, Liu Bin, Dai Guoxin, Xu Houjun, Yang Xuebing, Gong Jinxin, Jin Weiliang, Teng Yanjing, Luo Kaihai, Di Xiaotang and Bai Shengxiang
Chief reviewers of this standard: Lou Yu, LiuXila, Zhang Yongyi, Liu Qiongxiang, Zheng Wenzhong, Wu Ti, Wang Lijun, Li Yuanqi, Zhang Xinpei and Xue Huili
Contents
1 General Provisions 1
2 Terms and Symbols 1
2.1 Terms 1
2.2 Symbol 8
3 Basic Requirements 10
3.1 Basic Principles 10
3.2 Class of Safety and Reliability 11
3.3 Design Service Life and Durability 12
3.4 Reliability Management 13
4 Principle of Limit State Design 14
4.1 Limit States 14
4.2 Design Situations 15
4.3 Limit State Design 15
5 Actions on Structures and Environmental Influences 17
5.1 General Requirements 17
5.2 Actions on Structures 17
5.3 Environmental Influences 20
6 Properties of Materials and Geotechnics and Geometrical Quantities 20
6.1 Properties and Geotechnics of Materials 20
6.2 Geometrical Quantities 21
7 Structural Analysis and Design Assisted by Testing 22
7.1 General Requirements 22
7.2 Structural Modelling 22
7.3 Actions Modelling 22
7.4 Method of Structural Analysis 23
7.5 Design Assisted by Testing 23
8 Method of Partial Factors Design 24
8.1 General Requirements 24
8.2 Ultimate Limit States 25
8.3 Serviceability Limit States 29
Appendix A Assessment of Existing Structures 32
Appendix B Structural Integrity 39
Appendix C Design of Durability Limit States 42
Appendix D Quality Management 48
Appendix E Basis for Reliability and Method of Structural Reliability Design 50
Appendix F Design Assisted by Testing 57
Explanation of Wording in This Standard 61
List of Quoted Standards 62
Unified Standard for Reliability Design of Building Structures
1 General Provisions
1.0.1 This standard is formulated with a view to unify the basic principles, basic requirements and basic methods for the reliability design of building structures of various materials, to make the structures conform to the requirements of sustainable development, and to meet the requirements of safety and reliability, economy and rationality, advanced in techniques and quality assurance.
1.0.2 This standard is applicable to the design for entire structure, members of component, and ground and foundation, to the design at construction phase and use phase, and to the reliability assessment of existing structure. The reliability assessment of existing structures may be performed in accordance with the provisions of Appendix A of this standard.
1.0.3 This standard is formulated according to the principle of the current national standard Unified Standard for Reliability Design of Engineering Structures (GB 50153). It is the basic requirement for reliability design of building structures.
1.0.4 The method of limit state design based on probability theory and expressed by partial factors design shall be adopted in design of building structures. In the absence of statistical data, design of building structure can be based on reliable engineering experience or necessary experimental studies, or on empirical methods such as allowable stresses or single safety factors.
1.0.5 When formulating the load standard of building structure, the standard for design of building structures of various materials and other relevant standards, the basic criteria specified in this standard shall be complied with and the corresponding specific provisions shall be formulated.
1.0.6 In addition to this standard, the design of building structures shall also comply with those specified in the relevant current national standards.
2 Terms and Symbols
2.1 Terms
2.1.1 structure
system organically composed of connected parts that can withstand action and have appropriate stiffness
2.1.2 structural member
component whose structure is physically distinguishable.
2.1.3 structural system
all bearing members in the structure and the way they work together
2.1.4 structural model
ideal structural system for structural analysis, design, etc.
2.1.5 design service life
service life for intended purpose of the structures or structural components without being overhauled, as specified in design
2.1.6 design situations
a set of design conditions representing the actual situation in a certain period of time. The design shall be such that the structure does not exceed the relevant limit state
2.1.7 persistent design situation
a design situation that must appear in the process of use of structures, and the duration is very long, which is generally the same order of magnitude as the design service life
2.1.8 transient design situation
a design situation that with high occurrence probability in the process of construction and use of the structures, and the duration is short with respect to the design service life.
2.1.9 accidental design situation
a design situation that with low occurrence probability and the duration is very short
2.1.10 seismic design situation
a design situation of the structure under earthquake
2.1.11 load arrangement
reasonable determination of the position, size and direction of free action in the design of structures
2.1.12 load case
a certain compatible load arrangement, deformation and geometric deviation of a group of simultaneous fixed variable action, permanent action, free action for specific verification purposes
2.1.13 limit states
a certain functional requirements that the whole structure or part of it fails to meet the design requirements when exceeding specific state, such state is the limit state of this function
2.1.14 ultimate limit states
states corresponding to structures or structural members reaching the maximum load bearing capacity or not applicable to continuously bear the deformation
2.1.15 serviceability limit states
state corresponding to structures or structural members reaching certain specified limits of normal service
2.1.16 irreversible serviceability limit states
when the action beyond the normal use requirements is removed, the effect of the action can not be restored to the normal service limit state
2.1.17 reversible serviceability limit states
when the action beyond the normal use requirements is removed, the effect of the action can be restored to the normal service limit state
2.1.18 durability limit states
state corresponding to the deterioration of structures or structural members under the environmental influences to reach a specified limit or signof durability
2.1.19 resistance
ability of structures or structural members to withstand effects of action and environmental influences.
2.1.20 structural integrity; structural robustness
ability of structures as a whole to remain stable in the event of accidental events such as fire, explosion, impact, or human error, without damaging consequences disproportionate to the cause
2.1.21 key member; key element
structural member on which the ultimate state performance of structures bearing capacity depends
2.1.22 progressive collapse
initial local damage, spreading from member to member, eventually causes the entire structure to collapse or a portion of the structure to collapse out of proportion to the cause
2.1.23 reliability
structure capacity completing intended function under specified conditions within the specified time
2.1.24 degree of reliability; reliability
probability of structures completing intended function under specified conditions within the specified time.
2.1.25 probability of failure pf
probability that structures cannot completing intended function
2.1.26 reliability index β
numerical index that measures the reliability of structures. reliability index β is the inverse function of the standard normal distribution function with negative probability of failure pf
2.1.27 basic variable
a specified group of variables representing physical quantities and used to represent properties of actions and environmental influences, materials and geotechnics and geometrical quantities
2.1.28 performance function
function of basic variables, representing one type of structure performance
2.1.29 probability distribution
statistical pattern of random variable values, usually expressed by probability density function or probability distribution function
2.1.30 statistical parameter
digital characteristics representing the average level and dispersion degree of random variable values
2.1.31 fractile
value corresponding to some probability of the distribution function of random variables
2.1.32 nominal value
value determined by a nonstatistical method
2.1.33 limit state method
design method that does not cause structures to exceed a specified limit state
2.1.34 permissible stress method; allowable stress method
design method in which the stress of structures or foundation under standard values of action does not exceed the specified permissible stress
2.1.35 single safety factor method
design method in which the effect ratio between the standard value of resistance and the standard value of action of structures or foundation is not less than a specified safety factor
2.1.36 action
concentrated force or distributed force applied on structures and the cause of imposed or constrained deformations of structures. The former is direct action, also known as load; the latter is indirect action
2.1.37 imposed deformations
displacement and deformation of structures caused by the change of boundary conditions under the action of earthquake, uneven settlement and other factors
2.1.38 constrained deformations
internal deformation of structures due to external constraints caused by the influence of temperature change, humidity change and concrete shrinkage
2.1.39 effect of action
reaction of structures or structural members caused by actions
2.1.40 single action
function can be considered statistically independent in time and space from any other actions on the structure
2.1.41 permanent action
action always exists in the design service life and the change of its quantity value is negligible in contrast to the average value; or action with its variation is monotonous and tends to a limit
2.1.42 variable action
action of which the value varies with time during the design service life and of which the variation is non-negligible in contrast to the average value
2.1.43 accidental action
action that may not appear in the design service life, but once it appears, it has a large quantity and a short duration
2.1.44 seismic action
action of an earthquake on structures
2.1.45 geotechnical action
action transfer from geotechnical, fill, or groundwater to structures
2.1.46 fixed action
action has fixed spatial distribution on structures. When the magnitude and direction of the fixed action at a certain point of the structure are determined, the action on the whole structure can be determined
2.1.47 free action
action has arbitrary spatial distribution within a given range of structures
2.1.48 static action
action that acceleration generated by it on the structure can be negligible
2.1.49 dynamic action
action that acceleration generated by it on the structure can not be negligible
2.1.50 bounded action
action has definite or approximate mastery of the limit value that cannot be exceeded
2.1.51 unbounded action
action without clear boundary value
2.1.52 characteristic value of an action
main representative value of an action. It can be determined according to the statistics of observation data, natural limit of action or engineering experience
2.1.53 design reference period
time parameters chosen for value selection of changeable actions
2.1.54 combination value of a variable action
action value at which excessive probability of the combined effect of action in the design reference period is consistent with the corresponding probability of the action when appears only; or the action value of the reliable index which makes the structure have unified standard after combination. It can be expressed by the reduction of the characteristic value of an action by combination value factor
2.1.55 frequent value of a variable action
action value at which the excessive total period is only a small section of the design reference period in the design reference period; or the action value at which the excessive frequency is the specified value in the design reference period. It can be expressed by the reduction of the characteristic value of an action by frequent value factor
2.1.56 quasi-permanent value of a variable action
action value at which the excessive total period is one half of the design reference period in the design reference period. It can be expressed by the reduction of the characteristic value of an action by quasi-permanent value factor
2.1.57 accompanying value of a variable action
variable action value accompanying with a dominant action in an action combination. The accompanying value of a variable action may be combination value, frequent value or quasi-permanent value
2.1.58 representative value of an action
action value used in limit state design. It may be the characteristic value of an action or the accompanying value of a variable action
2.1.59 design value of an action
product of representative value of an action multiplied by the partial factor of action
2.1.60 combination of actions; load combination
a set of design values of an action used to verify the reliability of structure at limit state under the simultaneous influence of different actions
2.1.61 environmental influence
various mechanical, physical, chemical, or biological adverse influences of the environment on structures. Environmental influence may cause the deterioration of structural material property, reduce the safety or applicability of structures, and affect the durability of structures
2.1.62 characteristic value of a material property
a fractile of the probability distribution of material property that conforms to the specified quality or nominal value of material property
2.1.63 design value of a material property
value obtained by dividing the characteristic value of a material property by the partial factor of material property
2.1.64 characteristic value of a geometrical parameter
nominal value of geometrical parameter specified in the design or fractile of the probability distribution of geometrical parameter
2.1.65 design value of a geometrical parameter
value obtained by increasing or decreasing the additional value of a geometrical parameter on the base of characteristic value of a geometrical parameter
2.1.66 structural analysis
process or method of determining effect of action on structures
2.1.67 first order linear-elastic analysis
structural analysis of initial structural geometry is carried out by using elastic theory and based on the relationship between linear stress, strain or bending moment and curvature
2.1.68 second order linear-elastic analysis
structural analysis of deformed structural geometry is carried out by using elastic theory and based on the relationship between linear stress, strain or bending moment and curvature
2.1.69 first order or second order linear-elastic analysis with redistribution
structural analysis that carry out first or second order linear-elastic analysis for the adjustment of internal forces in structural design, which is in harmony with the given external action, and no clear calculation of the rotational capacity
2.1.70 first order non-linear analysis
structural analysis of initial structural geometry is carried out based on nonlinear deformation characteristics of materials
2.1.71 second order non-linear analysis
structural analysis of deformed structural geometry is carried out based on nonlinear deformation characteristics of materials
2.1.72 first order or second elastoplastic analysis
structural analysis of the moment-curvature relationship based on the linear elastic stage and the subsequent non-hardening stage
2.1.73 rigid plastic analysis
structural analysis that assuming the moment-curvature relationship is the stage of inelastic deformation and hardening, the ultimate bearing capacity of the geometry of initial structure is directly determined by limit analysis theory
2.1.74 existing structure
a variety of existing building structures
2.1.75 assessed working life
service life of an existing structure under specified conditions that estimated by reliability evaluation
2.1.76 load testing
A test to evaluate the properties of structures or structural members or to predict its bearing capacity by applying a load
2.2 Symbol
2.2.1 Capital Latin letters:
Ad — design value of accidental action;
C — corresponding limits specified by the design for deformation, crack, etc.;
Fd — design value of an action;
Fr — representative value of an action;
Gk — characteristic value of a permanent action;
P — relevant representative value of prestress action;
Qk — characteristic value of a variable action;
Rd — design value of resistance of structures or structural members;
S — effect of action of structures or structural members;
— effect of design value of accidental action;
Sd — design value of effect of combination of actions;
Sd,dst — design value of unbalanced effect of action;
Sd,stb — design value of balanced effect of action;
— effect of characteristic value of a permanent action;
SP — effect of representative value of a prestress action;
— effect of characteristic value of a variable action;
T — design reference period;
X — basic variable.
2.2.2 Lowercase Latin letters:
ad — design value of a geometrical parameter;
dk — characteristic value of a geometrical parameter;
fd — design value of a material property;
fk — characteristic value of a material property;
pf — calculated value of probability of failure of structural members.
2.2.3 Capital Greek letters:
Δa — additional quantities of geometrical parameters.
2.2.4 Lowercase Greek letters:
β — reliability index of structural members;
γ0 — importance coefficient of structures;
γF — partial factor of a action;
γG — partial factor of a permanent action;
γL — load adjustment factor in consideration of the design service life of structures;
γM — partial factor of a material property;
γ0 — partial factor of a variable action;
γP — partial factor of a prestress action;
ψc — factor of combination value of a action;
ψf — factor of frequent value of a action;
ψq — factor of quasi-permanent value of a action.
3 Basic Requirements
3.1 Basic Principles
3.1.1 The design, construction and maintenance of structures shall ensure that structures meets the specified functional requirements with the specified reliability within the specified design service life.
3.1.2 Structures shall meet the following functional requirements:
1 Able to withstand various functions that may occur during construction and service;
2 Maintain good service property;
3 Has sufficient durability;
4 In case of fire, sufficient bearing capacity can be maintained within the specified time;
5 When explosion, impact, human error and other accidental events occur, structures shall be able to maintain the necessary overall stability without damaging consequences disproportionate to the cause, and to prevent the continuous collapse of structures; The structural integrity may be designed in accordance with the provisions specified in Appendix B of this standard.
3.1.3 In the design of structures, appropriate measures shall be taken according to the following requirements to avoid or minimize possible damage to structures:
1 Avoid, eliminate or reduce possible damages to structures;
2 Use the structure type that is insensitive to the possible harm;
3 Use the structure type that can be preserved by the rest of the structure when a limited part of a single member or structure is accidentally removed or when acceptable partial damage occurs to the structure;
4 It is not suitable to use a structural system without damage warning;
5 Ensure the structural integrity of structures.
3.1.4 The following measures should be taken to meet the basic requirements of structures:
1 Use of appropriate materials;
2 Use of reasonable design and construction;
3 Development of corresponding control measures for the design, manufacture, construction and use of structures.
3.2 Class of Safety and Reliability
3.2.1 During the design of building structures, different classes of safety shall be adopted according to the possible consequences of structural damage, that is, the seriousness of endangering human life, causing economic losses, and having an impact on society or the environment. The division of classes of safety for building structures shall be in accordance with those specified in Table 3.2.1.
?
Table 3.2.1 Classes of safety for building structures
Class of safety Failure consequence
Class 1 Very serious: it has a great impact on people's life, economy, society or environment
Class 2 Serious: it has a more impact on people's life, economy, society or environment
Class 3 Not serious: it has a little impact on human life, economy, society or environment
3.2.2 The class of safety of all kinds of structural members in the building structures should be the same as that of the structures. The class of safety of partial structural members can be adjusted, but not lower than Class 3.
3.2.3 The class of reliability shall be set according to the class of safety, failure mode and economic factors of structural members. Different classes of reliability can be used for the safety, suitability and durability of structures.
3.2.4 When sufficient statistical data are available, reliability index β should be adopted for the reliability of structural members. The reliability index used in the design of structural members can be determined according to the reliability analysis of existing structural members, combined with the practical experience and economic factors.
3.2.5 For every class of safety of various structural members, the value of reliability index should be with a difference of 0.5.
3.2.6 The reliability index for the ultimate state design of bearing capacity of structural components in the permanent design condition shall not be less than those specified in Table 3.2.6.
Table 3.2.6 Reliability index β for structural members
Type of failure Class of safety
Class 1 Class 2 Class 3
Ductile failure 3.7 3.2 2.7
Brittle failure 4.2 3.7 3.2
3.2.7 The reliability index of normal service limit state design for the permanent design of structural members should be 0 to 1.5 according to their reversible degree.
3.2.8 The reliability index of durability limit state design for the permanent design of structural members should be 1.0 to 2.0 according to their reversible degree.
3.3 Design Service Life and Durability
3.3.1 The design reference period of building structures shall be 50 years.
3.3.2 During the design of building structures, the design service life shall be specified.
3.3.3 The design service life of building structures shall be in accordance with Table 3.3.3.
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbol
3 Basic Requirements
3.1 Basic Principles
3.2 Class of Safety and Reliability
3.3 Design Service Life and Durability
3.4 Reliability Management
4 Principle of Limit State Design
4.1 Limit States
4.2 Design Situations
4.3 Limit State Design
5 Actions on Structures and Environmental Influences
5.1 General Requirements
5.2 Actions on Structures
5.3 Environmental Influences
6 Properties of Materials and Geotechnics and Geometrical Quantities
6.1 Properties and Geotechnics of Materials
6.2 Geometrical Quantities
7 Structural Analysis and Design Assisted by Testing
7.1 General Requirements
7.2 Structural Modelling
7.3 Actions Modelling
7.4 Method of Structural Analysis
7.5 Design Assisted by Testing
8 Method of Partial Factors Design
8.1 General Requirements
8.2 Ultimate Limit States
8.3 Serviceability Limit States
Appendix A Assessment of Existing Structures
Appendix B Structural Integrity
Appendix C Design of Durability Limit States
Appendix D Quality Management
Appendix E Basis for Reliability and Method of Structural Reliability Design
Appendix F Design Assisted by Testing
Explanation of Wording in This Standard
List of Quoted Standards
1 總 則
1.0.1 為統(tǒng)一各種材料的建筑結(jié)構(gòu)可靠性設(shè)計(jì)的基本原則、基本要求和基本方法，使結(jié)構(gòu)符合可持續(xù)發(fā)展的要求，并符合安全可靠、經(jīng)濟(jì)合理、技術(shù)先進(jìn)、確保質(zhì)量的要求，制定本標(biāo)準(zhǔn)。
1.0.2本標(biāo)準(zhǔn)適用于整個(gè)結(jié)構(gòu)、組成結(jié)構(gòu)的構(gòu)件以及地基基礎(chǔ)的設(shè)計(jì)；適用于結(jié)構(gòu)施工階段和使用階段的設(shè)計(jì)；適用于既有結(jié)構(gòu)的可靠性評定。既有結(jié)構(gòu)的可靠性評定，可根據(jù)本標(biāo)準(zhǔn)附錄A的規(guī)定進(jìn)行。
1.0.3本標(biāo)準(zhǔn)依據(jù)現(xiàn)行國家標(biāo)準(zhǔn)《工程結(jié)構(gòu)可靠性設(shè)計(jì)統(tǒng)一標(biāo)準(zhǔn)》GB 50153的原則制定，是建筑結(jié)構(gòu)可靠性設(shè)計(jì)的基本要求。
1.0.4建筑結(jié)構(gòu)設(shè)計(jì)宜采用以概率理論為基礎(chǔ)、以分項(xiàng)系數(shù)表達(dá)的極限狀態(tài)設(shè)計(jì)方法；當(dāng)缺乏統(tǒng)計(jì)資料時(shí)，建筑結(jié)構(gòu)設(shè)計(jì)可根據(jù)可靠的工程經(jīng)驗(yàn)或必要的試驗(yàn)研究進(jìn)行，也可采用容許應(yīng)力或單一安全系數(shù)等經(jīng)驗(yàn)方法進(jìn)行。
1.0.5制定建筑結(jié)構(gòu)荷載標(biāo)準(zhǔn)、各種材料的結(jié)構(gòu)設(shè)計(jì)標(biāo)準(zhǔn)以及其他相關(guān)標(biāo)準(zhǔn)時(shí)，應(yīng)符合本標(biāo)準(zhǔn)規(guī)定的基本準(zhǔn)則，并應(yīng)制定相應(yīng)的具體規(guī)定。
1.0.6建筑結(jié)構(gòu)設(shè)計(jì)除應(yīng)符合本標(biāo)準(zhǔn)的規(guī)定外，尚應(yīng)符合國家現(xiàn)行有關(guān)標(biāo)準(zhǔn)的規(guī)定。
2術(shù)語和符號
2.1 術(shù) 語
2.1.1 結(jié)構(gòu) structure
能承受作用并具有適當(dāng)剛度的由各連接部件有機(jī)組合而成的系統(tǒng)。
2.1.2結(jié)構(gòu)構(gòu)件structural member
結(jié)構(gòu)在物理上可以區(qū)分出的部件。
2.1.3結(jié)構(gòu)體系 structural system
結(jié)構(gòu)中的所有承重構(gòu)件及其共同工作的方式。
2.1.4結(jié)構(gòu)模型structural model
用于結(jié)構(gòu)分析、設(shè)計(jì)等的理想化的結(jié)構(gòu)體系。
2.1.5設(shè)計(jì)使用年限design service life
設(shè)計(jì)規(guī)定的結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件不需進(jìn)行大修即可按預(yù)定目的使用的年限。
2.1.6設(shè)計(jì)狀況design situations
表征一定時(shí)段內(nèi)實(shí)際情況的一組設(shè)計(jì)條件，設(shè)計(jì)應(yīng)做到在該組條件下結(jié)構(gòu)不超越有關(guān)的極限狀態(tài)。
2.1.7持久設(shè)計(jì)狀況persistent design situation
在結(jié)構(gòu)使用過程中一定出現(xiàn)，且持續(xù)期很長的設(shè)計(jì)狀況，其持續(xù)期一般與設(shè)計(jì)使用年限為同一數(shù)量級。
2.1.8短暫設(shè)計(jì)狀況transient design situation
在結(jié)構(gòu)施工和使用過程中出現(xiàn)概率較大，而與設(shè)計(jì)使用年限相比，其持續(xù)期很短的設(shè)計(jì)狀況。
2.1.9偶然設(shè)計(jì)狀況accidental design situation
在結(jié)構(gòu)使用過程中出現(xiàn)概率很小，且持續(xù)期很短的設(shè)計(jì)狀況。
2.1.10地震設(shè)計(jì)狀況seismic design situation
結(jié)構(gòu)遭受地震時(shí)的設(shè)計(jì)狀況。
2.1.11 荷載布置load arrangement
在結(jié)構(gòu)設(shè)計(jì)中，對自由作用的位置、大小和方向的合理確定。
2.1.12荷載工況load case
為特定的驗(yàn)證目的，一組同時(shí)考慮的固定可變作用、永久作用、自由作用的某種相容的荷載布置以及變形和幾何偏差。
2.1.13極限狀態(tài)limit states
整個(gè)結(jié)構(gòu)或結(jié)構(gòu)的一部分超過某一特定狀態(tài)就不能滿足設(shè)計(jì)規(guī)定的某一功能要求，此特定狀態(tài)為該功能的極限狀態(tài)。
2.1.14 承載能力極限狀態(tài) ultimate limit states
對應(yīng)于結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件達(dá)到最大承載力或不適于繼續(xù)承載的變形的狀態(tài)。
2.1.15 正常使用極限狀態(tài) serviceability limit states
對應(yīng)于結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件達(dá)到正常使用的某項(xiàng)規(guī)定限值的狀態(tài)。
2.1.16不可逆正常使用極限狀態(tài) irreversible serviceability limit states
當(dāng)產(chǎn)生超越正常使用要求的作用卸除后，該作用產(chǎn)生的后果不可恢復(fù)的正常使用極限狀態(tài)。
2.1.17 可逆正常使用極限狀態(tài)reversible serviceability limit states
當(dāng)產(chǎn)生超越正常使用要求的作用卸除后，該作用產(chǎn)生的后果可以恢復(fù)的正常使用極限狀態(tài)。
2.1.18 耐久性極限狀態(tài)durability limit states
對應(yīng)于結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件在環(huán)境影響下出現(xiàn)的劣化達(dá)到耐久性能的某項(xiàng)規(guī)定限值或標(biāo)志的狀態(tài)。
2.1.19抗力 resistance
結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件承受作用效應(yīng)和環(huán)境影響的能力。
2.1.20結(jié)構(gòu)整體穩(wěn)固性 structural integrity；structural ro-bustness
當(dāng)發(fā)生火災(zāi)、爆炸、撞擊或人為錯(cuò)誤等偶然事件時(shí)，結(jié)構(gòu)整體能保持穩(wěn)固且不出現(xiàn)與起因不相稱的破壞后果的能力。
2.1.21關(guān)鍵構(gòu)件key member；key element
結(jié)構(gòu)承載能力極限狀態(tài)性能所依賴的結(jié)構(gòu)構(gòu)件。
2.1.22連續(xù)倒塌progressive collapse
初始的局部破壞，從構(gòu)件到構(gòu)件擴(kuò)展，最終導(dǎo)致整個(gè)結(jié)構(gòu)倒塌或與起因不相稱的一部分結(jié)構(gòu)倒塌。
2.1.23可靠性 reliability
結(jié)構(gòu)在規(guī)定的時(shí)間內(nèi)，在規(guī)定的條件下，完成預(yù)定功能的能力。
2.1.24可靠度degree of reliability；reliability
結(jié)構(gòu)在規(guī)定的時(shí)間內(nèi)，在規(guī)定的條件下，完成預(yù)定功能的概率。
2.1.25失效概率pf probability of failure pf
結(jié)構(gòu)不能完成預(yù)定功能的概率。
2.1.26可靠指標(biāo)β reliability index β
度量結(jié)構(gòu)可靠度的數(shù)值指標(biāo)，可靠指標(biāo)β為失效概率pf負(fù)的標(biāo)準(zhǔn)正態(tài)分布函數(shù)的反函數(shù)。
2.1.27基本變量 basic variable
代表物理量的一組規(guī)定的變量，用于表示作用和環(huán)境影響、材料和巖土的性能以及幾何參數(shù)的特征。
2.1.28功能函數(shù)performance function
關(guān)于基本變量的函數(shù)，該函數(shù)表征一種結(jié)構(gòu)功能。
2.1.29概率分布probability distribution
隨機(jī)變量取值的統(tǒng)計(jì)規(guī)律，一般采用概率密度函數(shù)或概率分布函數(shù)表示。
2.1.30統(tǒng)計(jì)參數(shù)statistical parameter
在概率分布中用來表示隨機(jī)變量取值的平均水平和離散程度的數(shù)字特征。
2.1.31分位值fractile
與隨機(jī)變量概率分布函數(shù)的某一概率相應(yīng)的值。
2.1.32名義值nominal value
用非統(tǒng)計(jì)方法確定的值。
2.1.33極限狀態(tài)法limit state method
不使結(jié)構(gòu)超越某種規(guī)定的極限狀態(tài)的設(shè)計(jì)方法。
2.1.34容許應(yīng)力法permissible stress method，allowable stress method
使結(jié)構(gòu)或地基在作用標(biāo)準(zhǔn)值下產(chǎn)生的應(yīng)力不超過規(guī)定的容許應(yīng)力的設(shè)計(jì)方法。
2.1.35單一安全系數(shù)法 single safety factor method
使結(jié)構(gòu)或地基的抗力標(biāo)準(zhǔn)值與作用標(biāo)準(zhǔn)值的效應(yīng)之比不低于某一規(guī)定安全系數(shù)的設(shè)計(jì)方法。
2.1.36作用action
施加在結(jié)構(gòu)上的集中力或分布力和引起結(jié)構(gòu)外加變形或約束變形的原因。前者為直接作用，也稱為荷載；后者為間接作用。
2.1.37外加變形imposed deformations
結(jié)構(gòu)在地震、不均勻沉降等因素作用下，邊界條件發(fā)生變化而產(chǎn)生的位移和變形。
2.1.38約束變形constrained deformations
結(jié)構(gòu)在溫度變化、濕度變化及混凝土收縮等因素作用下，由于存在外部約束而產(chǎn)生的內(nèi)部變形。
2.1.39作用效應(yīng)effect of action
由作用引起的結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件的反應(yīng)。
2.1.40單個(gè)作用single action
可認(rèn)為與結(jié)構(gòu)上的任何其他作用之間在時(shí)間和空間上為統(tǒng)計(jì)獨(dú)立的作用。
2.1.41 永久作用permanent action
在設(shè)計(jì)使用年限內(nèi)始終存在且其量值變化與平均值相比可以忽略不計(jì)的作用；或其變化是單調(diào)的并趨于某個(gè)限值的作用。
2.1.42可變作用variable action
在設(shè)計(jì)使用年限內(nèi)其量值隨時(shí)間變化，且其變化與平均值相比不可忽略不計(jì)的作用。
2.1.43偶然作用accidental action
在設(shè)計(jì)使用年限內(nèi)不一定出現(xiàn)，而一旦出現(xiàn)其量值很大，且持續(xù)期很短的作用。
2.1.44地震作用seismic action
地震動(dòng)對結(jié)構(gòu)所產(chǎn)生的作用。
2.1.45土工作用 geotechnical action
由巖土、填方或地下水傳遞到結(jié)構(gòu)上的作用。
2.1.46 固定作用 fixed action
在結(jié)構(gòu)上具有固定空間分布的作用。當(dāng)固定作用在結(jié)構(gòu)某一點(diǎn)上的大小和方向確定后，該作用在整個(gè)結(jié)構(gòu)上的作用即得以確定。
2.1.47 自由作用 free action
在結(jié)構(gòu)上給定的范圍內(nèi)具有任意空間分布的作用。
2.1.48靜態(tài)作用 static action
使結(jié)構(gòu)產(chǎn)生的加速度可以忽略不計(jì)的作用。
2.1.49 動(dòng)態(tài)作用dynamic action
使結(jié)構(gòu)產(chǎn)生的加速度不可忽略不計(jì)的作用。
2.1.50有界作用 bounded action
具有不能被超越的且可確切或近似掌握界限值的作用。
2.1.51 無界作用 unbounded action
沒有明確界限值的作用。
2.1.52作用的標(biāo)準(zhǔn)值characteristic value of an action
作用的主要代表值。可根據(jù)對觀測數(shù)據(jù)的統(tǒng)計(jì)、作用的自然界限或工程經(jīng)驗(yàn)確定。
2.1.53設(shè)計(jì)基準(zhǔn)期design reference period
為確定可變作用等取值而選用的時(shí)間參數(shù)。
2.1.54可變作用的組合值combination value of a variable ac-tion
使組合后的作用效應(yīng)的超越概率與該作用單獨(dú)出現(xiàn)時(shí)其標(biāo)準(zhǔn)值作用效應(yīng)的超越概率趨于一致的作用值；或組合后使結(jié)構(gòu)具有規(guī)定可靠指標(biāo)的作用值。可通過組合值系數(shù)對作用標(biāo)準(zhǔn)值的折減來表示。
2.1.55可變作用的頻遇值frequent value of a variable action
在設(shè)計(jì)基準(zhǔn)期內(nèi)被超越的總時(shí)間占設(shè)計(jì)基準(zhǔn)期的比率較小的作用值；或被超越的頻率限制在規(guī)定頻率內(nèi)的作用值。可通過頻遇值系數(shù)對作用標(biāo)準(zhǔn)值的折減來表示。
2.1.56可變作用的準(zhǔn)永久值 quasi-permanent value of a vari-able action
在設(shè)計(jì)基準(zhǔn)期內(nèi)被超越的總時(shí)間占設(shè)計(jì)基準(zhǔn)期的比率較大的作用值。可通過準(zhǔn)永久值系數(shù)對作用標(biāo)準(zhǔn)值的折減來表示。
2.1.57 可變作用的伴隨值accompanying value of a variable action
在作用組合中，伴隨主導(dǎo)作用的可變作用值。可變作用的伴隨值可以是組合值、頻遇值或準(zhǔn)永久值。
2.1.58作用的代表值representative value of an action
極限狀態(tài)設(shè)計(jì)所采用的作用值。它可以是作用的標(biāo)準(zhǔn)值或可變作用的伴隨值。
2.1.59作用的設(shè)計(jì)值design value of an action
作用的代表值與作用分項(xiàng)系數(shù)的乘積。
2.1.60作用組合combination of actions；荷載組合load com-bination
在不同作用的同時(shí)影響下，為驗(yàn)證某一極限狀態(tài)的結(jié)構(gòu)可靠度而采用的一組作用設(shè)計(jì)值。
2.1.61 環(huán)境影響 environmental influence
環(huán)境對結(jié)構(gòu)產(chǎn)生的各種機(jī)械的、物理的、化學(xué)的或生物的不利影響。環(huán)境影響會(huì)引起結(jié)構(gòu)材料性能的劣化，降低結(jié)構(gòu)的安全性或適用性，影響結(jié)構(gòu)的耐久性。
2.1.62材料性能的標(biāo)準(zhǔn)值characteristic value of a material prop-erty
符合規(guī)定質(zhì)量的材料性能概率分布的某一分位值或材料性能的名義值。
2.1.63材料性能的設(shè)計(jì)值design value of a material property
材料性能的標(biāo)準(zhǔn)值除以材料性能分項(xiàng)系數(shù)所得的值。
2.1.64幾何參數(shù)的標(biāo)準(zhǔn)值 characteristic value of a geomet-rical parameter
設(shè)計(jì)規(guī)定的幾何參數(shù)公稱值或幾何參數(shù)概率分布的某一分位值。
2.1.65幾何參數(shù)的設(shè)計(jì)值design value of a geometrical pa-rameter
幾何參數(shù)的標(biāo)準(zhǔn)值增加或減少一個(gè)幾何參數(shù)的附加量所得的值。
2.1.66結(jié)構(gòu)分析structural analysis
確定結(jié)構(gòu)上作用效應(yīng)的過程或方法。
2.1.67一階線彈性分析first order linear-elastic analysis
基于線性應(yīng)力-應(yīng)變或彎矩-曲率關(guān)系，采用彈性理論分析方法對初始結(jié)構(gòu)幾何形體進(jìn)行的結(jié)構(gòu)分析。
2.1.68二階線彈性分析second order linear-elastic analysis
基于線性應(yīng)力-應(yīng)變或彎矩-曲率關(guān)系，采用彈性理論分析方法對已變形結(jié)構(gòu)幾何形體進(jìn)行的結(jié)構(gòu)分析。
2.1.69有重分布的一階或二階線彈性分析 first order or sec-ond order linear-elastic analysis with redistribution
結(jié)構(gòu)設(shè)計(jì)中對內(nèi)力進(jìn)行調(diào)整的一階或二階線彈性分析，與給定的外部作用協(xié)調(diào)，不做明確的轉(zhuǎn)動(dòng)能力計(jì)算的結(jié)構(gòu)分析。
2.1.70一階非線性分析first order non-linear analysis
基于材料非線性變形特性對初始結(jié)構(gòu)的幾何形體進(jìn)行的結(jié)構(gòu)分析。
2.1.71二階非線性分析second order non-linear analysis
基于材料非線性變形特性對已變形結(jié)構(gòu)幾何形體進(jìn)行的結(jié)構(gòu)分析。
2.1.72一階或二階彈塑性分析 first order or second elasto-plastic analysis
基于線彈性階段和隨后的無硬化階段構(gòu)成的彎矩-曲率關(guān)系的結(jié)構(gòu)分析。
2.1.73剛性-塑性分析rigid plastic analysis
假定彎矩-曲率關(guān)系為無彈性變形和無硬化階段，采用極限分析理論對初始結(jié)構(gòu)的幾何形體進(jìn)行的直接確定其極限承載力的結(jié)構(gòu)分析。
2.1.74 既有結(jié)構(gòu) existing structure
已經(jīng)存在的各類建筑結(jié)構(gòu)。
2.1.75評估使用年限assessed working life
可靠性評定所預(yù)估的既有結(jié)構(gòu)在規(guī)定條件下的使用年限。
2.1.76荷載檢驗(yàn)load testing
通過施加荷載評定結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件的性能或預(yù)測其承載力的試驗(yàn)。
2.2 符 號
2.2.1大寫拉丁字母：
Ad——偶然作用的設(shè)計(jì)值；
C——設(shè)計(jì)對變形、裂縫等規(guī)定的相應(yīng)限值；
Fd——作用的設(shè)計(jì)值；
Fr——作用的代表值；
Gk——永久作用的標(biāo)準(zhǔn)值；
P——預(yù)應(yīng)力作用的有關(guān)代表值；
Qk——可變作用的標(biāo)準(zhǔn)值；
Rd——結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件抗力的設(shè)計(jì)值；
S——結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件的作用效應(yīng)；
——偶然作用設(shè)計(jì)值的效應(yīng)；
Sd——作用組合的效應(yīng)設(shè)計(jì)值；
Sd,dst——不平衡作用效應(yīng)的設(shè)計(jì)值；
Sd,stb——平衡作用效應(yīng)的設(shè)計(jì)值；
——永久作用標(biāo)準(zhǔn)值的效應(yīng)；
SP——預(yù)應(yīng)力作用有關(guān)代表值的效應(yīng)；
——可變作用標(biāo)準(zhǔn)值的效應(yīng)；
T——設(shè)計(jì)基準(zhǔn)期；
X——基本變量。
2.2.2小寫拉丁字母：
ad——幾何參數(shù)的設(shè)計(jì)值；
dk——幾何參數(shù)的標(biāo)準(zhǔn)值；
fd——材料性能的設(shè)計(jì)值；
fk——材料性能的標(biāo)準(zhǔn)值；
pf——結(jié)構(gòu)構(gòu)件失效概率的運(yùn)算值。
2.2.3大寫希臘字母：
Δa——幾何參數(shù)的附加量。
2.2.4小寫希臘字母：
β——結(jié)構(gòu)構(gòu)件的可靠指標(biāo)；
γ0——結(jié)構(gòu)重要性系數(shù)；
γF——作用的分項(xiàng)系數(shù)；
γG——永久作用的分項(xiàng)系數(shù)；
γL——考慮結(jié)構(gòu)設(shè)計(jì)使用年限的荷載調(diào)整系數(shù)；
γM——材料性能的分項(xiàng)系數(shù)；
γ0——可變作用的分項(xiàng)系數(shù)；
γP——預(yù)應(yīng)力作用的分項(xiàng)系數(shù)；
ψc——作用的組合值系數(shù)；
ψf——作用的頻遇值系數(shù)；
ψq——作用的準(zhǔn)永久值系數(shù)。
3 基本規(guī)定
3.1 基本要求
3.1.1結(jié)構(gòu)的設(shè)計(jì)、施工和維護(hù)應(yīng)使結(jié)構(gòu)在規(guī)定的設(shè)計(jì)使用年限內(nèi)以規(guī)定的可靠度滿足規(guī)定的各項(xiàng)功能要求。
3.1.2結(jié)構(gòu)應(yīng)滿足下列功能要求：
1 能承受在施工和使用期間可能出現(xiàn)的各種作用；
2保持良好的使用性能；
3具有足夠的耐久性能；
4 當(dāng)發(fā)生火災(zāi)時(shí)，在規(guī)定的時(shí)間內(nèi)可保持足夠的承載力；
5 當(dāng)發(fā)生爆炸、撞擊、人為錯(cuò)誤等偶然事件時(shí)，結(jié)構(gòu)能保持必要的整體穩(wěn)固性，不出現(xiàn)與起因不相稱的破壞后果，防止出現(xiàn)結(jié)構(gòu)的連續(xù)倒塌；結(jié)構(gòu)的整體穩(wěn)固性設(shè)計(jì)，可根據(jù)本標(biāo)準(zhǔn)附錄B的規(guī)定進(jìn)行。
3.1.3結(jié)構(gòu)設(shè)計(jì)時(shí)，應(yīng)根據(jù)下列要求采取適當(dāng)?shù)拇胧菇Y(jié)構(gòu)不出現(xiàn)或少出現(xiàn)可能的損壞：
1避免、消除或減少結(jié)構(gòu)可能受到的危害；
2 采用對可能受到的危害反應(yīng)不敏感的結(jié)構(gòu)類型；
3采用當(dāng)單個(gè)構(gòu)件或結(jié)構(gòu)的有限部分被意外移除或結(jié)構(gòu)出現(xiàn)可接受的局部損壞時(shí)，結(jié)構(gòu)的其他部分仍能保存的結(jié)構(gòu)類型；
4不宜采用無破壞預(yù)兆的結(jié)構(gòu)體系；
5使結(jié)構(gòu)具有整體穩(wěn)固性。
3.1.4宜采取下列措施滿足對結(jié)構(gòu)的基本要求：
1采用適當(dāng)?shù)牟牧希? 2采用合理的設(shè)計(jì)和構(gòu)造；
3對結(jié)構(gòu)的設(shè)計(jì)、制作、施工和使用等制定相應(yīng)的控制措施。
3.2安全等級和可靠度
3.2.1 建筑結(jié)構(gòu)設(shè)計(jì)時(shí)，應(yīng)根據(jù)結(jié)構(gòu)破壞可能產(chǎn)生的后果，即危及人的生命、造成經(jīng)濟(jì)損失、對社會(huì)或環(huán)境產(chǎn)生影響等的嚴(yán)重性，采用不同的安全等級。建筑結(jié)構(gòu)安全等級的劃分應(yīng)符合表3.2.1的規(guī)定。
表3.2.1 建筑結(jié)構(gòu)的安全等級
安全等級 破壞后果
一級 很嚴(yán)重：對人的生命、經(jīng)濟(jì)、社會(huì)或環(huán)境影響很大
二級 嚴(yán)重：對人的生命、經(jīng)濟(jì)、社會(huì)或環(huán)境影響較大
三級 不嚴(yán)重：對人的生命、經(jīng)濟(jì)、社會(huì)或環(huán)境影響較小
3.2.2建筑結(jié)構(gòu)中各類結(jié)構(gòu)構(gòu)件的安全等級，宜與結(jié)構(gòu)的安全等級相同，對其中部分結(jié)構(gòu)構(gòu)件的安全等級可進(jìn)行調(diào)整，但不得低于三級。
3.2.3可靠度水平的設(shè)置應(yīng)根據(jù)結(jié)構(gòu)構(gòu)件的安全等級、失效模式和經(jīng)濟(jì)因素等確定。對結(jié)構(gòu)的安全性、適用性和耐久性可采用不同的可靠度水平。
3.2.4 當(dāng)有充分的統(tǒng)計(jì)數(shù)據(jù)時(shí)，結(jié)構(gòu)構(gòu)件的可靠度宜采用可靠指標(biāo)β度量。結(jié)構(gòu)構(gòu)件設(shè)計(jì)時(shí)采用的可靠指標(biāo)，可根據(jù)對現(xiàn)有結(jié)構(gòu)構(gòu)件的可靠度分析，并結(jié)合使用經(jīng)驗(yàn)和經(jīng)濟(jì)因素等確定。
3.2.5各類結(jié)構(gòu)構(gòu)件的安全等級每相差一級，其可靠指標(biāo)的取值宜相差0.5。
3.2.6結(jié)構(gòu)構(gòu)件持久設(shè)計(jì)狀況承載能力極限狀態(tài)設(shè)計(jì)的可靠指標(biāo)，不應(yīng)小于表3.2.6的規(guī)定。
表3.2.6結(jié)構(gòu)構(gòu)件的可靠指標(biāo)β
破壞類型 安全等級
一級 二級 三級
延性破壞 3.7 3.2 2.7
脆性破壞 4.2 3.7 3.2
3.2.7結(jié)構(gòu)構(gòu)件持久設(shè)計(jì)狀況正常使用極限狀態(tài)設(shè)計(jì)的可靠指標(biāo)，宜根據(jù)其可逆程度取0～1.5。
3.2.8結(jié)構(gòu)構(gòu)件持久設(shè)計(jì)狀況耐久性極限狀態(tài)設(shè)計(jì)的可靠指標(biāo)，宜根據(jù)其可逆程度取1.0～2.0。
3.3設(shè)計(jì)使用年限和耐久性
3.3.1建筑結(jié)構(gòu)的設(shè)計(jì)基準(zhǔn)期應(yīng)為50年。
3.3.2建筑結(jié)構(gòu)設(shè)計(jì)時(shí)，應(yīng)規(guī)定結(jié)構(gòu)的設(shè)計(jì)使用年限。
3.3.3建筑結(jié)構(gòu)的設(shè)計(jì)使用年限，應(yīng)按表3.3.3采用。
表3.3.3建筑結(jié)構(gòu)的設(shè)計(jì)使用年限
類別 設(shè)計(jì)使用年限(年)
臨時(shí)性建筑結(jié)構(gòu) 5
易于替換的結(jié)構(gòu)構(gòu)件 25
普通房屋和構(gòu)筑物 50
標(biāo)志性建筑和特別重要的建筑結(jié)構(gòu) 100
3.3.4建筑結(jié)構(gòu)設(shè)計(jì)時(shí)應(yīng)對環(huán)境影響進(jìn)行評估，當(dāng)結(jié)構(gòu)所處的環(huán)境對其耐久性有較大影響日寸，應(yīng)根據(jù)不同的環(huán)境類別采用相應(yīng)的結(jié)構(gòu)材料、設(shè)計(jì)構(gòu)造、防護(hù)措施、施工質(zhì)量要求等，并應(yīng)制定結(jié)構(gòu)在使用期間的定期檢修和維護(hù)制度，使結(jié)構(gòu)在設(shè)計(jì)使用年限內(nèi)不致因材料的劣化而影響其安全或正常使用。
3.3.5環(huán)境對結(jié)構(gòu)耐久性的影響，可通過工程經(jīng)驗(yàn)、試驗(yàn)研究、計(jì)算、檢驗(yàn)或綜合分析等方法進(jìn)行評估；耐久性極限狀態(tài)設(shè)計(jì)可根據(jù)本標(biāo)準(zhǔn)附錄C的規(guī)定進(jìn)行。
3.3.6 環(huán)境類別的劃分和相應(yīng)的設(shè)計(jì)、施工、使用及維護(hù)的要求等，應(yīng)符合國家現(xiàn)行有關(guān)標(biāo)準(zhǔn)的規(guī)定。
3.4可靠性管理
3.4.1為保證建筑結(jié)構(gòu)具有規(guī)定的可靠性水平，除應(yīng)進(jìn)行設(shè)計(jì)計(jì)算外，還應(yīng)對結(jié)構(gòu)的材料性能、施工質(zhì)量、使用和維護(hù)進(jìn)行相應(yīng)的控制。控制的具體措施，應(yīng)符合本標(biāo)準(zhǔn)附錄D和有關(guān)的勘察、設(shè)計(jì)、施工及維護(hù)等標(biāo)準(zhǔn)的專門規(guī)定。
3.4.2建筑結(jié)構(gòu)的設(shè)計(jì)必須由具有相應(yīng)資格的技術(shù)人員承擔(dān)。
3.4.3建筑結(jié)構(gòu)的設(shè)計(jì)應(yīng)符合國家現(xiàn)行的有關(guān)荷載、抗震、地基基礎(chǔ)和各種材料結(jié)構(gòu)設(shè)計(jì)標(biāo)準(zhǔn)的規(guī)定。
3.4.4建筑結(jié)構(gòu)的設(shè)計(jì)應(yīng)對結(jié)構(gòu)可能受到的偶然作用、環(huán)境影響等采取必要的防護(hù)措施。
3.4.5對建筑結(jié)構(gòu)所采用的材料及施工、制作過程應(yīng)進(jìn)行質(zhì)量控制，并按國家現(xiàn)行有關(guān)標(biāo)準(zhǔn)的規(guī)定進(jìn)行驗(yàn)收。
3.4.6建筑結(jié)構(gòu)應(yīng)按設(shè)計(jì)規(guī)定的用途使用，并應(yīng)定期檢查結(jié)構(gòu)狀況，進(jìn)行必要的維護(hù)和維修；當(dāng)需變更使用用途時(shí)，應(yīng)進(jìn)行設(shè)計(jì)復(fù)核并采取相應(yīng)的技術(shù)措施。
4極限狀態(tài)設(shè)計(jì)原則
4.1 極限狀態(tài)
4.1.1極限狀態(tài)可分為承載能力極限狀態(tài)、正常使用極限狀態(tài)和耐久性極限狀態(tài)。極限狀態(tài)應(yīng)符合下列規(guī)定：
1 當(dāng)結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件出現(xiàn)下列狀態(tài)之一時(shí)，應(yīng)認(rèn)定為超過了承載能力極限狀態(tài)：
1)結(jié)構(gòu)構(gòu)件或連接因超過材料強(qiáng)度而破壞，或因過度變形而不適于繼續(xù)承載；
2)整個(gè)結(jié)構(gòu)或其一部分作為剛體失去平衡；
3)結(jié)構(gòu)轉(zhuǎn)變?yōu)闄C(jī)動(dòng)體系；
4)結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件喪失穩(wěn)定；
5)結(jié)構(gòu)因局部破壞而發(fā)生連續(xù)倒塌；
6)地基喪失承載力而破壞；
7)結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件的疲勞破壞。
2 當(dāng)結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件出現(xiàn)下列狀態(tài)之一時(shí)，應(yīng)認(rèn)定為超過了正常使用極限狀態(tài)：
1)影響正常使用或外觀的變形；
2)影響正常使用的局部損壞；
3)影響正常使用的振動(dòng)；
4)影響正常使用的其他特定狀態(tài)。
3 當(dāng)結(jié)構(gòu)或結(jié)構(gòu)構(gòu)件出現(xiàn)下列狀態(tài)之一時(shí)，應(yīng)認(rèn)定為超過了耐久性極限狀態(tài)：
1)影響承載能力和正常使用的材料性能劣化；
2)影響耐久性能的裂縫、變形、缺口、外觀、材料削弱等；
3)影響耐久性能的其他特定狀態(tài)。
4.1.2對結(jié)構(gòu)的各種極限狀態(tài)，均應(yīng)規(guī)定明確的標(biāo)志或限值。
4.1.3結(jié)構(gòu)設(shè)計(jì)時(shí)應(yīng)對結(jié)構(gòu)的不同極限狀態(tài)分別進(jìn)行計(jì)算或驗(yàn)算；當(dāng)某一極限狀態(tài)的計(jì)算或驗(yàn)算起控制作用時(shí)，可僅對該極限狀態(tài)進(jìn)行計(jì)算或驗(yàn)算。
4.2設(shè)計(jì)狀況
4.2.1 建筑結(jié)構(gòu)設(shè)計(jì)應(yīng)區(qū)分下列設(shè)計(jì)狀況：
1持久設(shè)計(jì)狀況，適用于結(jié)構(gòu)使用時(shí)的正常情況；
2 短暫設(shè)計(jì)狀況，適用于結(jié)構(gòu)出現(xiàn)的臨時(shí)情況，包括結(jié)構(gòu)施工和維修時(shí)的情況等；
3偶然設(shè)計(jì)狀況，適用于結(jié)構(gòu)出現(xiàn)的異常情況，包括結(jié)構(gòu)遭受火災(zāi)、爆炸、撞擊時(shí)的情況等；
4地震設(shè)計(jì)狀況，適用于結(jié)構(gòu)遭受地震時(shí)的情況。
4.2.2對不同的設(shè)計(jì)狀況，應(yīng)采用相應(yīng)的結(jié)構(gòu)體系、可靠度水平、基本變量和作用組合等進(jìn)行建筑結(jié)構(gòu)可靠性設(shè)計(jì)。
4.3極限狀態(tài)設(shè)計(jì)
4.3.1 對本標(biāo)準(zhǔn)第4.2.1條規(guī)定的四種建筑結(jié)構(gòu)設(shè)計(jì)狀況，應(yīng)分別進(jìn)行下列極限狀態(tài)設(shè)計(jì)：
1 對四種設(shè)計(jì)狀況均應(yīng)進(jìn)行承載能力極限狀態(tài)設(shè)計(jì)；
2對持久設(shè)計(jì)狀況尚應(yīng)進(jìn)行正常使用極限狀態(tài)設(shè)計(jì)，并宜進(jìn)行耐久性極限狀態(tài)設(shè)計(jì)；
3對短暫設(shè)計(jì)狀況和地震設(shè)計(jì)狀況可根據(jù)需要進(jìn)行正常使用極限狀態(tài)設(shè)計(jì)；
4對偶然設(shè)計(jì)狀況可不進(jìn)行正常使用極限狀態(tài)和耐久性極限狀態(tài)設(shè)計(jì)。
4.3.2進(jìn)行承載能力極限狀態(tài)設(shè)計(jì)時(shí)，應(yīng)根據(jù)不同的設(shè)計(jì)狀況采用下列作用組合：
1 對于持久設(shè)計(jì)狀況或短暫設(shè)計(jì)狀況，應(yīng)采用作用的基本組合；
2對于偶然設(shè)計(jì)狀況，應(yīng)采用作用的偶然組合；
3對于地震設(shè)計(jì)狀況，應(yīng)采用作用的地震組合。
4.3.3進(jìn)行正常使用極限狀態(tài)設(shè)計(jì)時(shí)，宜采用下列作用組合：
1對于不可逆正常使用極限狀態(tài)設(shè)計(jì)，宜采用作用的標(biāo)準(zhǔn)組合；
2 對于可逆正常使用極限狀態(tài)設(shè)計(jì)，宜采用作用的頻遇組合；
3對于長期效應(yīng)是決定性因素的正常使用極限狀態(tài)設(shè)計(jì)，宜采用作用的準(zhǔn)永久組合。
4.3.4對每一種作用組合，建筑結(jié)構(gòu)的設(shè)計(jì)均應(yīng)采用其最不利的效應(yīng)設(shè)計(jì)值進(jìn)行。
4.3.5結(jié)構(gòu)的極限狀態(tài)可采用下列極限狀態(tài)方程描述：
g(X1，X2，…，Xn)=0 (4.3.5)
式中： g(·)——結(jié)構(gòu)的功能函數(shù)；
Xi(i=1，2，…，n)——基本變量，指結(jié)構(gòu)上的各種作用和環(huán)境影響、材料和巖土的性能及幾何參數(shù)等；在進(jìn)行可靠度分析時(shí)，基本變量應(yīng)作為隨機(jī)變量。
4.3.6結(jié)構(gòu)按極限狀態(tài)設(shè)計(jì)應(yīng)符合下列規(guī)定：
g(X1，X2，…，Xn)≥0 (4.3.6)
4.3.7 當(dāng)采用結(jié)構(gòu)的作用效應(yīng)和結(jié)構(gòu)的抗力作為綜合基本變量時(shí)，結(jié)構(gòu)按極限狀態(tài)設(shè)計(jì)應(yīng)符合下列規(guī)定：
R-S≥0 (4.3.7)
式中：R——結(jié)構(gòu)的抗力；
S——結(jié)構(gòu)的作用效應(yīng)。
4.3.8結(jié)構(gòu)構(gòu)件的設(shè)計(jì)應(yīng)以規(guī)定的可靠度滿足本標(biāo)準(zhǔn)第4.3.6或第4.3.7條的要求。
4.3.9結(jié)構(gòu)構(gòu)件宜根據(jù)規(guī)定的可靠指標(biāo)，采用由作用的代表值、材料性能的標(biāo)準(zhǔn)值、幾何參數(shù)的標(biāo)準(zhǔn)值和各相應(yīng)的分項(xiàng)系數(shù)構(gòu)成的極限狀態(tài)設(shè)計(jì)表達(dá)式進(jìn)行設(shè)計(jì)；有條件時(shí)也可根據(jù)本標(biāo)準(zhǔn)附錄E的規(guī)定，直接采用基于可靠指標(biāo)的方法進(jìn)行設(shè)計(jì)。
