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According to the requirements of the Ministry of Housing and Urban-Rural Development of the People's Republic of China-"Notice on Printing 'Development and Revision Plan of National Engineering Construction Standards and Codes in 2009'" (Jian Biao [2009] No. 88), this code is revised from the national standard "Load Code for the Design of Building Structures" GB 50009-2001 (2006 Edition) by the China Academy of Building Research jointly with the organizations concerned. During the revision process, the drafting group seriously summed up the design experience in recent years, made reference to the relevant content of the foreign codes and international standards, developed multiple monographic studies, extensively solicited for the comments of construction competent departments as well as design, research and teaching organizations nationally, and finally finalized upon review through repeated discussion, modification and trial design.
This code comprises 10 chapters and 9 appendixes with the main technical contents as follows: general provisions, terms and symbols, classification and combination of loads, permanent load, live load on floors and roofs, crane load, snow load, wind load, thermal action and accidental load.
The main technical contents in the revision of this code: 1. the provisions for adjustment coefficient of variable load considering design working life are added; 2. the accidental load combination expression is added; 3. Chapter 4 "Permanent Load" is added; 4. the characteristic values of uniformly distributed live loads on floors and roofs of partial civil buildings are adjusted and supplemented, and the provisions for the value of live load of fire engine in the design of wall, column and foundation are modified, and the live loads on railings are modified and supplemented; 5. the conditions of nonuniform snow distribution on partial roofs are supplemented; 6. the exposure factor for wind load and the peak topography correction coefficient are adjusted; 7. the shape factor of wind load and the local shape factor are supplemented and perfected, the value range of interference effect coefficient of tall building complex is supplemented, and the provisions for wind tunnel test equipment and method requirements are added; 8. the calculation expression and calculation parameter of along-wind vibration coefficient are modified, and the provisions for the calculation principle of the wind vibration of large-span roof structures are added; 9. the provisions for the calculation of equivalent wind load for across-wind and torsional vibration are added, and the provisions for the combination conditions of along-wind load and equivalent wind load for across-wind and torsional vibration are added; 10. the calculation formula and table of gust factor are modified; 11. Chapter 9 "Thermal Action" is added; 12. Chapter 10 "Accidental Load" is added; 13. Appendix B "Reduction Factor of Fire Engine Load Accounting for the Influence of Covered Soil" is added; 14. the reference snow pressure and reference wind pressure of partial cities are adjusted by counting the snow pressure and wind pressure of each meteorological station throughout the country again based on the new observed data, and the new reference snow pressure and reference wind pressure maps throughout the country are drawn; 15. the reference air temperature of each meteorological station throughout the country are given by counting based on the monthly average maximum and monthly average minimum air temperature data over the years, and the reference air temperature distribution maps throughout the country are added; 16. Appendix H "Equivalent Wind Load for Across-wind and Torsional Vibration" is added; 17. Appendix J "Acceleration of Wind Induced Along-wind and Across-wind Vibration for Tall Buildings" is added.
In this code, the provision(s) printed in bold type is (are) compulsory one(s) 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 code and the explanation of the compulsory provisions, and the China Academy of Building Research is responsible for the explanation of specific technical contents. During the process of implementing this code, the relevant opinions or advice, whenever necessary, can be posted or passed on to the national standard "Load Code for the Design of Building Structures" Administrative Group of China Academy of Building Research (address: No. 30, North Third Ring East Road, Beijing, 100013, China).
Chief development organization of this code: China Academy of Building Research
Participating development organizations of this code: Tongji University
China Architecture Design and Research Group
China Institute of Building Standard Design & Research
Beijing Institute of Architectural Design
CMA Public Meteorological Service Center
Harbin Institute of Technology
Dalian University of Technology
China Aviation Planning and Construction Development Co., Ltd.
East China Architectural Design & Research Institute Co., Ltd.
Southwestern Architectural Design Institute Co., Ltd.
Central-South Architectural Design Institute Co., Ltd.
Shenzhen General Institute of Architectural Design and Research
Zhejiang Prov. Institute of Architectural Design and Research
Chief drafting staff of this code: Jin Xinyang (the following ones are arranged according to family name strokes)
Wang Jian, Wang Guoyan, Feng Yuan, Zhu Dan, Gong Jinxin, Li Ting, Yang Zhenbin, Yang Weibiao, Shu Weinong, Chen Kai, Fan Zhong, Fan Feng, Lin Zheng, Gu Ming, Tang Yi, Han Jisheng
Chief examiners of this code: Cheng Maokun, Wang Dasui, Xu Yongji, Chen Jifa
Xue Heng, Ren Qingying, Lou Yu, Yuan Jinxi, Zuo Jiang, Wu Yihong, Mo Yong, Zheng Wenzhong, Fang Xiaodan, Zhang Yiping, Fan Xiaoqing
Contents
1 General Provisions 1
2 Terms and Symbols 1
2.1 Terms 1
2.2 Symbols 3
3 Classification and Combination of Loads 5
3.1 Classification of Loads and Representative Values of Loads 5
3.2 Combination of Loads 6
4 Permanent Load 9
5 Live Load on Floors and Roofs 10
5.1 Uniformly Distributed Live Loads on Floors in Civil Buildings 10
5.2 Live Loads on Floors in Industrial Buildings 12
5.3 Live Loads on Roofs 13
5.4 Ash Load on Roofs 14
5.5 Construction and maintenance loads, Horizontal and Vertical Loads on Railings 16
5.6 Dynamic Coefficient 16
6 Crane Load 17
6.1 Vertical and Horizontal Crane Loads 17
6.2 Combination of Multi-cranes 17
6.3 Dynamic Coefficients of Crane Loads 18
6.4 Combination Value, Frequent Value and Quasi-permanent Value of Crane Load 18
7 Snow Load 18
7.1 Characteristic Value of Snow Load and Reference Snow Pressure 18
7.2 Distribution Factor for Roof Snow Load 19
8 Wind Load 22
8.1 Characteristic Value of Wind Load and Reference Wind Pressure 22
8.2 Exposure Factor for Wind Pressure 23
8.3 Shape Factor of Wind Load 25
8.4 Along-wind Vibration and Dynamic Response Factor 41
8.5 Across-wind and Wind-induced Torsional Vibration 43
8.6 Gust Factor 45
9 Thermal Action 46
9.1 General 46
9.2 Reference Air Temperature 46
9.3 Uniform Temperature Action 47
10 Accidental Load 47
10.1 General 47
10.2 Explosion 48
10.3 Impact 48
Appendix A Self-weight of Commonly Used Materials and Members 50
Appendix B Reduction Factor of Fire Engine Load Accounting for the Influence of Covered Soil 63
Appendix C Determination Method of Equivalent Uniformly Distributed Live Loads on Floors 64
Appendix D Live Loads on Floors of Industrial Buildings 69
Appendix E Determination Method of Reference Snow Pressure, Wind Pressure and Temperature 75
Appendix F Empirical Formula for Fundamental Natural Period of Structures 103
Appendix G Approximate Vibration Mode Shape of Structures 105
Appendix H Equivalent Wind Load for Across-wind and Torsional Vibration 107
Appendix J Acceleration of Wind Induced Along-wind and Across-wind Vibration for Tall Buildings 114
Explanation of Wording in this Code 117
List of Quoted Standards 118
1 General Provisions
1.0.1 This code is formulated with a view to adapting the need of the building structure design and meeting the requirements of safety and usability, economy and rationality.
1.0.2 This code is applicable to the structural design of building engineering.
1.0.3 This code is formulated in accordance with the basic principles specified in the national standard "Unified Standard for Reliability Design of Engineering Structures" GB 50153-2008.
1.0.4 The actions concerned in the building structure design shall cover direct action (load) and indirect action. This code only specifies load and thermal action, and the provisions for the relevant variable load are also applicable to the thermal action.
1.0.5 The loads concerned in the building structure design shall not only comply with this code, but also those in the current relevant ones of the nation.
2 Terms and Symbols
2.1 Terms
2.1.1 Permanent load
Load of which the value does not vary with time during the structure use period, or of which the variation may be neglected compared with the average value, or of which the variation is monotonous and trends to the limit.
2.1.2 Variable load
Load of which the value varies with time during the structure use period, and of which the variation cannot be neglected compared with the average value.
2.1.3 Accidental load
Load which does not always occur within the design working life of the structure, but its quantity value is very large once occurred and its duration is very short.
2.1.4 Representative values of a load
They are used to check the quantity value of loads adopted in the limit state in the design, such as characteristic value, combination value, frequent value and quasi-permanent value.
2.1.5 Design reference period
Time parameter which is selected to determine the representative value of variable load.
2.1.6 Characteristic value/nominal value
Basic representative value of load and characteristic value of maximum load statistical distribution within the design reference period (such as mean, mode, median or some tantile).
2.1.7 Combination value
For variable load, load value which can make the exceedance probability of the combined load effect within the design reference period consistent with the corresponding probability when this load occurs separately; or load value which can make the combined structure have a unified reliability index.
2.1.8 Frequent value
For variable load, load value that the total exceedance time is the specified smaller ratio or the exceedance frequency is the specified frequency within the design reference period.
2.1.9 Quasi-permanent value
For variable load, load value that the total exceedance time is about one half of the design reference period within the design reference period.
2.1.10 Design value of a load
Product of representative value and partial coefficient of a load.
2.1.11 Load effect
Reaction of structure or structural member caused by load, such as internal force, deformation and cracking.
2.1.12 Load combination
Provisions for various design values of loads emerging simultaneously in order to ensure structure reliability in the limit state design.
2.1.13 Fundamental combination
Combination of permanent load and variable load in calculation of limit state of bearing capacity.
2.1.14 Accidental combination
Combination of permanent load, variable load and one accidental load in calculation of limit state of bearing capacity, and combination of permanent load and variable load in checking of monolithic stability of damaged structure after accidental event occurs.
2.1.15 Characteristic/nominal combination
Combination that adopts characteristic value or combination value as the representative value of a load in calculation of limit state of normal use.
2.1.16 Frequent combination
For variable load, combination that adopts frequent value or quasi-permanent value as the representative value of a load in calculation of limit state of normal use.
2.1.17 Quasi-permanent combination
For variable load, combination that adopts quasi-permanent value as the representative value of a load in calculation of limit state of normal use.
2.1.18 Equivalent uniform live load
Discontinuously distributed actual load on floor in structural design, which is generally replaced with uniform load; the equivalent uniform live load refers to the uniform load that the load effect obtained from its structure can keep consistent with the actual load effect.
2.1.19 Tributary area
Floor area for member load calculation in consideration of uniform load reduction of members such as beam and column.
2.1.20 Dynamic coefficient
Equivalent coefficient adopted for structure or member bearing dynamic load in static design, of which the value is the ratio of maximum dynamic effect to corresponding static effect of structure or member.
2.1.21 Reference snow pressure
Reference pressure of snow load, generally determined based on the 50-year maximum value obtained through probability statistics according to the snow self-weight observation data on the local open and flat ground surface.
2.1.22 Reference wind pressure
Reference pressure of wind load, wind speed generally determined based on the 50-year maximum value obtained through probability statistics according to the 10min average wind speed observation data at 10m height on the local open and flat ground surface, and wind pressure determined reconsidering corresponding air density according to Bernoulli Formula (E.2.4).
2.1.23 Terrain roughness
Grade for describing the distribution condition of irregular obstructions above this ground where wind blows across 2km range before reaching the structure.
2.1.24 Thermal action
Action caused by temperature variation in structure or structural member.
2.1.25 Shade air temperature
Temperature measured in a standard thermometer screen and recorded at regular time by the hour.
2.1.26 Reference air temperature
Reference value of air temperature, which is determined through statistics according to the average maximum air temperature in the months with maximum temperature and the average minimum air temperature in the months with minimum temperature over the years by taking 50-year monthly average maximum air temperature and monthly average minimum air temperature.
2.1.27 Uniform temperature
Temperature which is a constant in the whole section of the structural member and leads the expansion or contraction of the structural member.
2.1.28 Initial temperature
Temperature when the structure forms an entirely-confined structural system in some particular construction stage, also called healing temperature.
2.2 Symbols
2.2.1 Representative values and combinations of loads
Ad——Characteristic value of accidental load;
C——Specified limit when the structure or member reaches the normal use requirements;
Gk——Characteristic value of permanent load;
Qk——Characteristic value of variable load;
Rd——Design value of resistance of structural member;
S_(A_d )——Characteristic value of accidental load effect;
SGk——Characteristic value of permanent load effect;
SQk——Characteristic value of variable load effect;
Sd——Design value of load effect combination;
γ0——Significance coefficient of structure;
γG——Partial coefficient of permanent load;
γQ——Partial coefficient of variable load;
γ_(L_j )——Adjustment coefficient of variable load considering design working life;
ψc——Combination value coefficient of variable load;
ψf——Frequent value coefficient of variable load;
ψq——Quasi-permanent value coefficient of variable load.
2.2.2 Snow load and wind load
aD,z——Acceleration of along-wind vibration at z height of tall buildings (m/s2);
aL,z——Acceleration of across-wind vibration at z height of tall buildings (m/s2);
B——Windward side width of structure;
Bz——Background component factor of fluctuating wind load;
C'L——Across-wind force coefficient;
C'T——Wind-induced torque coefficient;
Cm——Angle edge correction coefficient of across-wind force;
Csm——Angle edge correction coefficient of power spectrum of across-wind force;
D——Structural plane depth (along-wind dimension) or diameter;
f1——Natural vibration frequency of the first order of structure;
fT1——Natural vibration frequency of the first order torsion of structure;
f1*——Reduced frequency;
f_T1^*——Reduced frequency of torsion;
FDk——Characteristic value of along-wind force in unit height;
FLk——Characteristic value of along-wind force in unit height;
TTk——Characteristic value of wind-reduced torque in unit height;
g——Gravity acceleration or peak factor;
H——Structure height or peak height;
I10——Nominal turbulence intensity of wind at 10m height;
KL——Correction coefficient of across-wind vibration mode;
KT——Correction coefficient of torsional vibration mode;
R——Resonant component factor of fluctuating wind load;
RL——Resonance factor of across-wind vibration;
RT——Resonance factor of wind-induced torsional vibration;Re——Reynolds number;
St——Strouhal number;
Sk——Characteristic value of snow load;
S0——Reference snow pressure;
T1——Natural vibration period of the first order of structure;
TL1——Natural vibration period of the across-wind first order of structure;
TT1——Natural vibration period of the first order of structure torsion;
ω0——Reference wind pressure;
ωk——Characteristic value of wind load;
ωLk——Characteristic value of wind load equivalent to across-wind vibration;
ωTk——Characteristic value of wind load equivalent to wind-induced torsional vibration;
α——Slope angle, or wind speed profile index;
βz——Dynamic response factor at z height;
βgz——Gust factor;
υcr——Critical wind speed of across-wind resonance;
υH——Wind speed at the top of structure;
μr——Distribution factor for roof snow load;
μz——Exposure factor for wind pressure;
μs——Shape factor of wind load;
μsl——Local shape factor of wind load;
η——Correction coefficient of wind load landform;
ηa——Fluctuation coefficient of acceleration of along-wind vibration;
ρ——Air density or snow density;
ρx and ρz——Correlation coefficient of fluctuating wind load in horizontal and vertical directions;
φz——Coefficient of vibration mode of structure;
ζ——Damping ratio of structure;
ζa——Across-wind aerodynamic damping ratio.
2.2.3 Thermal action
Tmax and Tmin——Monthly average maximum air temperature and monthly average minimum air temperature;
Ts,max and Ts,min——Maximum average temperature and minimum average temperature of structure;
T0,max and T0,min——Maximum initial temperature and minimum initial temperature of structure;
ΔTk——Characteristic value of uniform temperature action;
αT——Coefficient of linear expansion of materials.
2.2.4 Accidental load
Av——Area of access plate (m2);
Kdc——Dynamic coefficient for calculating equivalent uniformly distributed static load in explosion;
m——Mass of automobile or helicopter;
Pk——Characteristic value of impact load;
pc——Maximum pressure of uniform dynamic load in explosion;
pv——Verified breakdown pressure of access plate;
qce——Characteristic value of equivalent uniformly distributed static load in explosion;
t——Impact time;
υ——Automobile speed (m/s);
V——Volume of explosion space.
3 Classification and Combination of Loads
3.1 Classification of Loads and Representative Values of Loads
3.1.1 The loads of the building structures may be classified into:
1 Permanent load, including structure self-weight, soil pressure, prestress, etc.
2 Variable load, including live load on floor, live load on roof and ash load, crane load, wind load, snow load, thermal action, etc.
3 Accidental load, including explosive force, impact force, etc.
3.1.2 In the design of building structures, the different loads shall adopt different representative values according to the following requirements:
1 For permanent load, the characteristic value shall be its representative value;
2 For variable load, the characteristic value, combination value, frequent value or quasi-permanent value shall be its representative value according to the design requirements;
3 For accidental load, its representative value shall be determined according to the use characteristics of the building structures.
3.1.3 The determination of the representative value of variable load shall adopt 50-year design reference period.
3.1.4 The characteristic values of loads shall be adopted according to the requirements of each chapter of this code.
3.1.5 In the design of limit state of bearing capacity or the design of limit state of normal use according to the characteristic combination, for variable load, the combination value or characteristic value shall be its representative value according to the specified load combination. The combination value of variable load shall be the characteristic value of variable load multiplied by the load combination value coefficient.
3.1.6 In the design of limit state of normal use according to frequent combination, for variable load, the frequent value or quasi-permanent value shall be its representative value; in the design according to quasi-permanent combination, the quasi-permanent value of variable load shall be its representative value. The frequent value of variable load shall be the characteristic value of variable load multiplied by the frequent value coefficient. The quasi-permanent value of variable load shall be the characteristic value of variable load multiplied by the quasi-permanent value coefficient.
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Classification and Combination of Loads
3.1 Classification of Loads and Representative Values of Loads
3.2 Combination of Loads
4 Permanent Load
5 Live Load on Floors and Roofs
5.1 Uniformly Distributed Live Loads on Floors in Civil Buildings
5.2 Live Loads on Floors in Industrial Buildings
5.3 Live Loads on Roofs
5.4 Ash Load on Roofs
5.5 Construction and maintenance loads, Horizontal and Vertical Loads on Railings
5.6 Dynamic Coefficient
6 Crane Load
6.1 Vertical and Horizontal Crane Loads
6.2 Combination of Multi-cranes
6.3 Dynamic Coefficients of Crane Loads
6.4 Combination Value, Frequent Value and Quasi-permanent Value of Crane Load
7 Snow Load
7.1 Characteristic Value of Snow Load and Reference Snow Pressure
7.2 Distribution Factor for Roof Snow Load
8 Wind Load
8.1 Characteristic Value of Wind Load and Reference Wind Pressure
8.2 Exposure Factor for Wind Pressure
8.3 Shape Factor of Wind Load
8.4 Along-wind Vibration and Dynamic Response Factor
8.5 Across-wind and Wind-induced Torsional Vibration
8.6 Gust Factor
9 Thermal Action
9.1 General
9.2 Reference Air Temperature
9.3 Uniform Temperature Action
10 Accidental Load
10.1 General
10.2 Explosion
10.3 Impact
Appendix A Self-weight of Commonly Used Materials and Members
Appendix B Reduction Factor of Fire Engine Load Accounting for the Influence of Covered Soil
Appendix C Determination Method of Equivalent Uniformly Distributed Live Loads on Floors
Appendix D Live Loads on Floors of Industrial Buildings
Appendix E Determination Method of Reference Snow Pressure, Wind Pressure and Temperature
Appendix F Empirical Formula for Fundamental Natural Period of Structures
Appendix G Approximate Vibration Mode Shape of Structures
Appendix H Equivalent Wind Load for Across-wind and Torsional Vibration
Appendix J Acceleration of Wind Induced Along-wind and Across-wind Vibration for Tall Buildings
Explanation of Wording in this Code
List of Quoted Standards
