GB 50011-2010Code for seismic design of buildings (English PDF)

1.0.1

This code is formulated with a view to implementing the relevant laws and regulations on construction engineering and protecting against and mitigating earthquake disasters, carrying out the policy of “prevention first”, as well as alleviating the seismic damage of buildings, avoiding casualties and reducing economic loss through seismic precautionary of buildings.

The basic seismic precautionary objectives of buildings which designed and constructed in accordance with this code, are as follows:

1) under the frequent earthquake ground motion with an intensity being less than the local Seismic Precautionary Intensity, the buildings with major structure undamaged or requiring no repair may continue to serve;

2) under the earthquake ground motion with an intensity being equivalent to the local Seismic Precautionary Intensity, the buildings with possible damage may continue to serve with common repair; or

3) under the rare earthquake ground motion with an intensity being larger than the local Seismic Precautionary Intensity, the buildings shall not collapse or shall be free from such severe damage that may endanger human lives.

If the buildings with special requirements in functions or other aspects are carried out with the seismic performance-based design, more concrete and higher seismic precautionary objectives shall be established.

1.0.2

All the buildings situated on zones of Seismic Precautionary Intensity 6 or above must be carried out with seismic design.

1.0.3

This code is applicable to the seismic design and the isolation and energy-dissipation design of the buildings suited on zones of Seismic Precautionary Intensity 6, 7, 8 and 9. And the seismic performance-based design of buildings may be implemented in accordance with the basic methods specified in this code.

As for the buildings suited on zones where the Seismic Precautionary Intensity is above Intensity 9 and the industrial buildings for special purpose, their seismic design shall be carried out according to the relevant special provisions.

Note: For the purposes of this code, “Seismic Precautionary Intensity 6, 7, 8 and 9” hereinafter is referred to “Intensity 6, 7, 8 and 9”.

1.0.4

The Seismic Precautionary Intensity must be determined in accordance with the documents (drawings) examined, approved and issued by the authorities appointed by the State.

1.0.5

Generally, the seismic precautionary intensity of buildings shall be adopted with the basic seismic intensity (the intensity values corresponding to the design basic acceleration of ground motion value in this code) determined according to the “Seismic Ground Motion Parameter Zonation Map of China”.

1.0.6

In addition to the requirements of this code, the seismic design of buildings also shall comply with the requirements specified in the relevant current standards of the State.

2.1 Terms

2.1.1 Seismic precautionary intensity

The seismic intensity approved by the authority appointed by the State, which is used as the basis for the seismic precaution of buildings in a certain region. Generally, it is taken as the seismic Intensity with a 10% probability of exceedance in 50 years.

2.1.2 Seismic precautionary criterion

The rule for judging the seismic precautionary requirements, which is dependent on the Seismic Precautionary Intensity or the design parameters of ground motion and the precautionary category of buildings.

2.1.3 Seismic ground motion parameter zonation map

The map in which the whole county is divided into regions with different seismic precautionary requirements according to the ground motion parameter (that is the degree of earthquake ground motion intensity indicated by acceleration).

2.1.4 Earthquake action

The dynamic response of structure caused by earthquake ground motion, including horizontal and vertical earthquake action.

2.1.5 Design parameters of earthquake ground motion

The parameters of earthquake ground motion used in seismic design, including the acceleration (velocity or displacement) time history of the earthquake ground motion , the acceleration response spectrum and the peak value of ground acceleration

2.1.6 Design basic acceleration of earthquake ground motion

The design value of seismic acceleration with a 10% probability of exceedance in the 50-years design reference period.

2.1.7 Design characteristic period of earthquake ground motion

The period value corresponding to the starting point of the descending section of the seismic influence coefficient curve used for seismic design, that is dependent on the earthquake magnitude, epicentral distance, site class and etc. For convenience, it is named as “characteristic period” for short.

2.1.8 Site

Locations of the project colonies, being with similar characteristics of response spectra. The scope of site is equivalent to plant area, residential area and natural village or the plane area no less than 1.0km2.

2.1.9 Seismic concept design of buildings

The process of making the general arrangement for the buildings and structures and of determining details, based on the fundamental design principles and concepts obtained from the past experiences in earthquake disasters and projects.

2.1.10 Seismic measures

The seismic design contents except earthquake action calculation and member resistance calculation, including the details of seismic design.

2.1.11 Details of seismic design

All the detailed requirements that must be taken for the structural and nonstructural components according to seismic concept design principles and require no calculation generally.

2.2 Symbols

2.2.1 Actions and effects

FEk, FEvk - - Standard values of total horizontal and vertical earthquake actions of structure respectively;

GE, Geq - - Representative value of gravity load of structure (or component) and the total equivalent representative value of gravity load of a structure ,respectively;

wK - - Standard value of wind load;

SE - - Seismic effect (bending moment, axial force, shear, stress and deformation);

S - - Fundamental combination values of the effects of earthquake action and other loads;

Sk - - Effect of the standard value of action or load;

M - - Bending moment;

N - - Axial force;

V - - Shear;

p - - Pressure on bottom of foundation;

u - - Lateral displacement;

theta - - Storey drift

2.2.2 Material properties and resistance

K - - Stiffness of structure (member);

R - - Resistant capacity of structural component;

f, fk, fE - - Design value, standard value and seismic design value of various material strength (including the bearing capacity of soil) , respectively;

[theta] - - Allowable storey drift.

2.2.3 Geometric parameters

A - - Cross-sectional area of member;

As - - Cross-sectional area of reinforcement;

B - - Total width of structure;

H - - Total height of structure, or the column height;

L - - Total length of structure (unit);

alpha - - Distance;

as, a's - - Minimal distance from the force point of the longitudinal tensile and compressive reinforcements to the margin of section, respectively;

b - - Sectional width of member;

d - - Depth or thickness of soil layer, or the diameter of reinforcement;

h - - Depth of cross-section of member;

l - - Length or span of member;

t - - Thickness of wall or floor slab.

2.2.4 Coefficients of calculation

alpha - - Horizontal seismic influence coefficient;

alphamax - - Maximum value of horizontal seismic influence coefficient;

alphavmax - - Maximum value of vertical seismic influence coefficient;

gammaG, gammaE, gammaW - - Partial factor of action;

gammaRE - - seismic adjusting factor for load-bearing capacity;

zeta - - Calculation coefficient;

eta - - Enhancement or adjustment coefficient of earthquake action effect (internal force or deformation);

lambda - - Slenderness ratio of member, or the proportionality coefficient;

xiy - - Yield strength coefficient of structure (member);

rho - - Reinforcement ratio or ratio;

ø - - Stability coefficient of compressive member;

- - Combination value coefficient or the influence coefficient.

2.2.5 Others

T - - Natural vibration period of structure;

N - - Penetration resistance (in blow number);

IlE - - Liquefaction index of soil under earthquake;

Xji - - The coordinate of modal displacement (relative displacement of the ith mass point of the jth mode in x direction);

Yji - - The coordinate of modal displacement (relative displacement of the ith mass point of the jth mode in y direction);

n - - Total number, such as number of storeys, masses, reinforcements and spans, etc.;

upsilonse - - Equivalent shear wave velocity of soil layer;

Phiji - - The coordinate of modal rotation (relative rotation of the ith mass point of the jth mode around the z axial direction).

3.1 Category and Criterion for Seismic Precaution of Buildings

3.1.1

The seismic precautionary category and the seismic precautionary criterion of buildings shall be determined in accordance with the current national standard GB 50223 “Standard for Classification of Seismic Protection of Building Constructions”.

3.1.2

Unless otherwise specified in this code, Categories B, C and D buildings with seismic precautionary intensity 6 may not be carried out the calculation of earthquake action.

3.2 Earthquake Ground Motion

3.2.1

The earthquake ground motion of the zones in which buildings are suited shall be represented by design basic acceleration and characteristic period of earthquake ground motion corresponding to the seismic precautionary intensity.

3.2.2

The corresponding relationship between the seismic precautionary intensity and the design basic acceleration of ground motion shall be in accordance with those specified in Table 3.2.2. Unless otherwise stated in this code, the buildings in such zones where the design basic acceleration of ground motion is 0.15g and 0.30g shall be carried out with seismic design respectively according to the requirements of seismic precautionary intensity 7 and 8.

Table 3.2.2 Corresponding Relationship Between Seismic Precautionary Intensity and Design Basic Acceleration of Ground Motion

Seismic precautionary intensity 6 7 8 9

Design basic acceleration value of ground motion 0.05g 0.10 (0.15)g 0.20 (0.30)g 0.40g

Note: g is the gravity acceleration.

3.2.3

The characteristic period of earthquake ground motion shall be determined according to the design earthquake groups and the site class of the building site. The design earthquakes in this code are totally divided into three groups, and their characteristic periods shall be adopted according to the relevant provisions in Chapter 5 of this code.

3.2.4

The seismic precautionary intensity, design basic acceleration of ground motion and design earthquake groups of the central areas in the main cities in China may be adopted according to Appendix A of this code.