Standards related to:

GB 50009-2012GB 50009-2012

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

UDC

P GB 50009-2012

Load Code for the Design of Building Structures

ISSUED ON: MAY 28, 2012

IMPLEMENTED ON: OCTOBER 1, 2012

Issued by: Ministry of Housing and Urban-Rural Construction of the People’s Republic

of China;

General Administration of Quality Supervision, Inspection and Quarantine

of the People’s Republic of China.

Table of Contents

1 General Provisions ... 8

2 Terms and Symbols ... 9

2.1 Terms ... 9

2.2 Symbols ... 11

3 Classification and Combination of Loads ... 15

3.1 Classification of Loads and Representative Values of Loads ... 15

3.2 Combination of Loads ... 15

4 Permanent Load ... 20

5 Live Load on Floors and Roofs ... 21

5.1 Uniformly Distributed Live Loads on Floors in Civil Buildings ... 21

5.2 Live Loads on Floors in Industrial Buildings ... 23

5.3 Live Loads on Roofs ... 24

5.4 Ash Load on Roofs ... 25

5.5 Construction and Maintenance Loads, Horizontal and Vertical Loads on Railings ... 26

5.6 Dynamic Coefficient ... 27

6 Crane Load ... 28

6.1 Vertical and Horizontal Crane Loads ... 28

6.2 Combination of Multi-cranes ... 28

6.3 Dynamic Coefficients of Crane Loads ... 29

6.4 Combination Value, Frequent Value and Quasi-permanent Value of Crane Load ... 29

7 Snow Load ... 30

7.1 Characteristic Value of Snow Load and Reference Snow Pressure ... 30

7.2 Distribution Factor for Roof Snow Load ... 30

8 Wind Load ... 34

8.1 Characteristic Value of Wind Load and Reference Wind Pressure ... 34

8.2 Exposure Factor for Wind Pressure ... 35

8.3 Shape Factor of Wind Load ... 36

8.4 Along-wind Vibration and Dynamic Response Factor ... 57

8.5 Across-wind and Wind-induced Torsional Vibration ... 59

8.6 Gust Factor ... 61

9 Thermal Action ... 62

9.1 General Requirements ... 62

9.2 Reference Air Temperature ... 62

9.3 Uniform Temperature Action... 63

10 Accidental Load ... 64

10.1 General Requirements ... 64

10.2 Explosion ... 64

10.3 Impact ... 65

Appendix A Self-weight of Commonly Used Materials and Members ... 66

Appendix B Reduction Factor of Fire Engine Load Accounting for the Influence of Covered

Soil ... 78

Appendix C Determination Method of Equivalent Uniformly Distributed Live Loads on

Floors ... 79

Appendix D Live Loads on Floors of Industrial Buildings ... 83

Appendix E Determination Method of Reference Snow Pressure, Wind Pressure and

Temperature ... 88

Appendix F Empirical Formula for Fundamental Natural Period of Structures ... 118

F.1 High-rise Structures ... 118

F.2 Tall Buildings ... 120

Appendix G Approximate Vibration Mode Shape of Structures ... 121

Appendix H Equivalent Wind Load for Across-wind and Torsional Vibration ... 123

H.1 Equivalent Wind Load for Across-wind Vibration of Structures of Circular Section ... 123

H.2 Equivalent Wind Load for Across-wind Vibration of Structures of Rectangular Section . 124

H.3 Equivalent Wind Load for Torsional Vibration of Structures of Rectangular Section ... 129

Appendix J Acceleration of Wind Induced Along-wind and Across-wind Vibration for Tall

Buildings ... 131

J.1 Calculation of Acceleration of Along-wind Vibration ... 131

J.2 Calculation of Acceleration of Across-wind Vibration ... 132

Explanation of Wording in this Code ... 134

List of Quoted Standards ... 135

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.

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-yeardesign

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.

3.2 Combination of Loads

3.2.1 In the design of the building structures, load combination shall be carried out according to the

limit state of bearing capacity and the limit state of normal use respectively based on the loads possibly

emerging simultaneously on the structure during the use process, and the respective most unfavorable

combination shall be taken for design.

3.2.2 For the limit state of bearing capacity, the effect design value of load combination shall be

7 Snow Load

7.1 Characteristic Value of Snow Load and Reference Snow Pressure

7.1.1 The characteristic value of snow load on roofs in horizontal projection plane shall be

calculated according to the following formula:

Sk=μrs0 (7.1.1)

Where Sk——The characteristic value of snow load (kN/m2);

μr——The distribution factor for roof snow load;

s0——The reference snow pressure (kN/m2).

7.1.2 The reference snow pressure shall adopt the snow pressure with 50-year recurrence

interval, which is determined according to the method specified in this code; for the structure

sensitive to snow load, the snow pressure with 100-year recurrence interval shall be adopted.

7.1.3 The reference snow pressure of all the cities throughout the country shall be adopted according

to the value with a recurrence interval R of 50 years in Table E.5 of Appendix E of this code. Where

the reference snow pressure of a city or construction site is not given in Table E.5 of this code, the

reference snow pressure shall be determined through statistical analysis according to the method

specified in Appendix E of this code, in accordance with the local annual maximum snow pressure or

snow depth data, and on the basis of the definition of reference snow pressure; and the analysis shall

consider the influence of sample size. In the absence of local snow pressure and snow depth data, the

reference snow pressure may be determined through comparative analysis on meteorological and

topographic conditions according to the reference snow pressure or long-term data specified for

nearby areas, or determined approximately according to Annexed Figure E.6.1 Distribution Map of

Reference Snow Pressure throughout the Country in Appendix E of this code.

7.1.4 The snow load in mountain area shall be determined through actual investigation. In the

absence of measured data, the snow load may be adopted according to the snow load value of local

adjacent open and flat ground surface multiplied by a coefficient of 1.2.

7.1.5 The combination value coefficient of snow load may take 0.7; the frequent value coefficient

may take 0.6; the quasi-permanent value coefficient shall take 0.5, 0.2 and 0 respectively according to

Zones I, II and III of snow load; the snow load zones shall be adopted in accordance with those

specified in Appendix E.5 or Annexed Figure E.6.2 of this code.

7.2 Distribution Factor for Roof Snow Load

7.2.1 The distribution factor for roof snow load shall be adopted in accordance with those specified

in Table 7.2.1 according to the roof type of different categories.

7.2.2 In the design of building structures and supporting members of roofs, the snow distribution

condition shall be adopted according to the following requirements:

1 The roof slab and purlin shall be adopted according to the most unfavorable condition of

nonuniform snow distribution;

8 Wind Load

8.1 Characteristic Value of Wind Load and Reference Wind Pressure

8.1.1 The characteristic value of wind load vertical to the building surface shall be determined

according to the following requirements:

1 In the calculation of main load-carrying structures, the characteristic value of wind

load shall be calculated according to the following formula:

wk=βzμsμzw0 (8.1.1-1)

Where wk——The characteristic value of wind load (kN/m2);

βz——The dynamic response factor at z height;

μs——The shape factor of wind load;

μz——The exposure factor for wind pressure;

w0——The reference wind pressure (kN/m2).

2 In the calculation of enclosure structures, the characteristic value of wind load shall be

calculated according to the following formula:

wk=βgzμslμzw0 (8.1.1-2)

Where βgz——The gust factor at z height;

μsl——The local shape factor of wind load.

8.1.2 The reference wind pressure shall adopt the wind pressure with 50-year recurrence

interval, which is determined according to the method specified in this code, but shall not be less

than 0.3kN/m2. For the tall buildings, high-rise structures and other structures sensitive to wind

load, the reference wind pressure value shall be increased properly, shall meet the requirements

of the relevant code for the design of structures.

8.1.3 The reference wind pressure of all the cities throughout the country shall be adopted according

to the value with a recurrence interval R of 50 years in Table E.5 of Appendix E of this code. Where

the reference wind pressure of a city or construction site is not given in Table E.5 of this code, the

reference wind pressure shall be determined through statistical analysis according to the method

specified in Appendix E of this code and in accordance with the definition of reference wind pressure

and the local annual maximum wind speed data; and the analysis shall consider the influence of

sample size. In the absence of local wind speed data, the reference wind pressure may be determined

through comparative analysis on meteorological and topographic conditions according to the reference

wind pressure or long-term data specified for nearby areas, or determined approximately according to

Annexed Figure E.6.3 Distribution Map of Reference Wind Pressure throughout the Country in

Appendix E of this code.

8.1.4 The combination value coefficient, frequent value coefficient and quasi-permanent value

coefficient of wind load may take 0.6, 0.4 and 0.0 respectively.

3 Other conditions shall be valued according to μsl of open buildings.

Note: 1 The opening ratio of dominant opening refers to the ratio of the area of single dominant opening to the whole area of this

wall;

2 μsl shall take the value of corresponding dominant opening position.

8.3.6 For the wind tunnel test of building structures, the test equipment, test methods and data

processing shall meet the requirements of the relevant codes.

8.4 Along-wind Vibration and Dynamic Response Factor

8.4.1 For the buildings with height greater than 30m and height-width ratio greater than 1.5 and

various high-rise structures with fundamental natural period T1 greater than 0.25s, the along-wind

vibration influence of wind pressure fluctuation on structures shall be considered. The response

calculation of along-wind vibration shall be carried out according to the theory of random vibration of

structures. For the structures meeting the requirements of Article 8.4.3 of this code, the along-wind

load may be calculated through dynamic response factor method.

Note: 1 The natural vibration period of structures shall be calculated according to the structural dynamics; the approximate

fundamental natural period T1 may be calculated according to Appendix F;

2 The acceleration of along-wind vibration of tall buildings may be calculated according to Appendix J of this code.

8.4.2 For the flexible roof structures sensitive to wind or with span greater than 36m, the wind

vibration influence of wind pressure fluctuation on structures shall be considered. The wind vibration

response of roof structures should be determined through calculation according to the random

vibration theory based on the wind tunnel test results.

8.4.3 For general vertical cantilever structures, e.g. Tall buildings and high-rise structures such as

framework, tower frame and chimney, only the influence of the first vibration mode of the structures

may be considered; the along-wind load of the structures may be calculated according to Formula

(8.1.1-1). The dynamic response factor βz at z height may be calculated according to the following

formula:

Z10z 121 RBgI (8.4.3)

Where g——The peak factor, taking 2.5;

I10——The nominal turbulence intensity of 10m height, taking 0.12, 0.14, 0.23 and 0.39

corresponding to Category A, B, C and D terrain roughness respectively;

R——The resonant component factor of fluctuating wind load;

Bz——The background component factor of fluctuating wind load.

8.4.4 The resonant component factor of fluctuating wind load may be calculated according to the

following formula:

3/42

1 )1(6 x

πR (8.4.4-1)

8.4.6 The space correlation coefficient of fluctuating wind load may be determined according to the

following requirements:

1 The correlation coefficient in vertical direction may be calculated according to the following

formula:

H H 60e6010 60/

(8.4.6-1)

Where H——The total height of structure (m), shall not be greater than 300m, 350m, 450m and

550m corresponding to Category A, B, C and D terrain roughness respectively.

2 The correlation coefficient in horizontal direction may be calculated according to the following

formula:

B B 50e5010 50/

(8.4.6-2)

Where B——The windward side width of structure (m), B≤2H.

3 For high-rise structures with smaller windward side width, the correlation coefficient in

horizontal direction may take ρx=1.

8.4.7 The coefficient of vibration mode shall be determined according to structure dynamic calculation.

For the high-rise structures of vertical cantilever type, whose shape, mass and rigidity vary continuously

and regularly along the height, and the relatively uniform tall buildings along the height, the

coefficient of vibration mode φ1 (z) may also be determined according to Appendix G of this code in

accordance with the relative height z/H.

8.5 Across-wind and Wind-induced Torsional Vibration

8.5.1 For the tall buildings with obvious across-wind vibration action effect and the structures of

slender circular section, the influence of across-wind vibration should be considered.

8.5.2 The equivalent wind load of across-wind vibration may be adopted according to the following

requirements:

1 For the tall buildings and high-rise structures with complex plane or elevation shape, the

equivalent wind load ωLk of across-wind vibration should be determined through a wind tunnel test, or

determined according to the relevant data;

2 For the tall buildings and structures of circular section, the equivalent wind load ωLk of

across-wind vibration caused by trans-critical strong wind resonance (vortex shedding) may be

determined according to Appendix H.1 of this code;

3 For the tall buildings of rectangular section and of concave or chamfered rectangular section,

the equivalent wind load ωLk of across-wind vibration may be determined according to Appendix H.2

of this code.

Note: The acceleration of across-wind vibration of tall buildings may be calculated according to Appendix J of this code.

8.5.3 For the structures of circular section, the across-wind vibration (vortex shedding) shall be

checked for different Reynolds numbers Re according to the following requirements:

1 Where Re< 3×105 and the wind speed υH at the top of the structures is greater than υcr, the

subcritical breeze resonance may occur. In this case, antivibration measures may be taken structurally

or the critical wind speed υcr of the structures may be controlled as no less than 15m/s.

2 Where Re≥3.5×106 and 1.2 times the wind speed υH at the top of the structures is greater than

υcr, the crossing critical strong wind resonance may occur; in this case, the equivalent wind load of

across-wind vibration shall be considered.

3 Where 3×105≤Re< 3.5×106, the wind vibration beyond critical range may not be handled.

4 The Reynolds number Re may be determined according to the following formula:

Re=69000υD (8.5.3-1)

Where υ——The wind speed for calculation, taking the critical wind speed value υcr;

D——The diameter of structure section (m), where the structure section reduces along the

height (inclination not greater than 0.02), the diameter at 2/3 structure height may be

approximately taken.

5 The critical wind speed υcr and the wind speed υH at the top of the structures may be

determined according to the following formulae:

StT

cr (8.5.3-2)

0HH 2000 (8.5.3-3)

Where Ti——The natural vibration period of the ith vibration mode of structure, taking the

fundamental natural period Ti in the checking of subcritical breeze resonance;

St——The Strouhal number, taking 0.2 for the structures of circular section;

μH——The exposure factor for wind pressure at the top of structure;

ω0——The reference wind pressure (kN/m2);

ρ——The air density (kg/m3).

8.5.4 For the tall buildings and high-rise structures with obvious wind-induced torsional vibration

action effect, the influence of wind-induced torsional vibration should be considered.

8.5.5 The equivalent wind load of wind-induced torsional vibration may be adopted according to the

following requirements:

1 For the tall buildings with complex shape and obviously eccentric mass or rigidity, the

equivalent wind load ωTk of wind-induced torsional vibration should be determined through a wind

tunnel test, or determined according to the relevant data;

determined according to the method specified in Appendix E of this code; the reference air temperature

values of the cities throughout the country may be adopted according to Table E.5 in Appendix E of

this code. Where the reference air temperature value of a city or construction site is not given in

Appendix E of this code, the reference air temperature value may be determined through statistical

analysis according to the method specified in Appendix E based on the air temperature data recorded

by local meteorological station. In the absence of local air temperature data, the reference air

temperature may be determined through comparative analysis on meteorological and topographic

conditions according to the reference air temperature specified for nearby areas, or determined

approximately according to Figure E.6.4 and Figure E.6.5 in Appendix E of this code.

9.2.2 For the structures such as metal structures which are sensitive to air temperature variation, the

influence of extreme air temperature should be considered; the reference air temperature Tmax and Tmin

may be properly increased or decreased according to the local climate conditions.

9.3 Uniform Temperature Action

9.3.1 The characteristic value of uniform temperature action shall be determined according to the

following requirements:

1 For the operating condition of structures at maximum temperature rise, the characteristic

value of uniform temperature action shall be calculated according to the following formula:

ΔTk=Ts,max−T0,min (9.3.1-1)

Where ΔTk——The characteristic value of uniform temperature action (℃);

Ts,max——The maximum average temperature of structure (℃);

T0,min——The minimum initial average temperature of structure (℃).

2 For the operating condition of structures at maximum temperature drop, the characteristic

value of uniform temperature action shall be calculated according to the following formula:

ΔTk=Ts,min−T0,max (9.3.1-2)

Where Ts,min——The minimum average temperature of structure (℃);

T0,max——The maximum initial average temperature of structure (℃).

9.3.2 The maximum average temperature Ts,max and the minimum average temperature Ts,min of the

structures should be determined according to the heat engineering principle in accordance with

reference air temperature Tmax and Tmin respectively. For the indoor structures with enclosure, their

average temperature shall consider the influence of indoor and outdoor temperature difference; for the

structures exposed outdoors or structures during construction period, the influence of solar radiation

should be considered according to the structure orientation and surface heat absorptivity.

9.3.3 The maximum initial average temperature T0,max and the minimum initial average temperature

T0,max of the structures shall be determined according to the structure healing or restraint forming time,

or determined according to the unfavorable condition based on the possible structure temperature

during construction.

10 Accidental Load

10.1 General Requirements

10.1.1 The accidental load shall cover the loads caused by explosion, impact, fire and other

accidental disasters. This chapter is only applicable to explosion and impact load.

10.1.2 Where the accidental load is used as the dominant load in structural design, the structure shall

be ensured without progressive collapse caused by accidental load under the condition that local

member damage is allowed for the structure.

10.1.3 The design value of accidental load may directly take the characteristic value of accidental

load determined according to the method specified in this chapter.

10.2 Explosion

10.2.1 The explosion load caused by explosive, gas and dust, etc. should be adopted according to

the equivalent static load.

10.2.2 Under the action of dynamic explosion load of routine explosive, the characteristic value of

equivalent uniformly distributed static load of structural members may be calculated according to the

following formula:

qce=Kdcpc (10.2.2)

Where qce——The characteristic value of equivalent uniformly distributed static load acting on

structural members;

pc——The maximum pressure of uniformly distributed dynamic load acting on structural

members, may be adopted according to the relevant requirements of Article 4.3.2

and Article 4.3.3 of the national standard “Code for Design of Civil Air Defence

Basement” GB 50038−2005;

Kdc——The dynamic coefficient, determined according to the principle of equivalent

maximum internal force based on the dynamic analysis result under the action of

uniformly distributed dynamic load for the members.

Note: For the explosion caused by other reasons, the equivalent uniformly distributed static load may be determined according to the

equivalent TNT charging quantity by reference to the method of this article.

10.2.3 For the building structures with access plate, where the ratio of the access plate area Av to the

explosion space volume V is 0.05~0.15, and the volume V is less than 1000m3, the equivalent uniformly

distributed static load pk of gas explosion may be calculated according to the following formula and

shall take the larger value:

pk=3+pV (10.2.3-1)

Vk 04.05.03

App (10.2.3-2)

...