GB 50003-2011Code for design of masonry structures (English PDF)

1.0.1

This code is formulated with a view to implementing the technical and economic policies of the nation, persisting in wall material innovation, adjusting measures to local conditions, using local materials, reasonably selecting structural scheme and masonry materials, and achieving advanced technology, safety and usability, economy and rationality and quality guarantee.

1.0.2

This code is applicable to the design of the following masonry structures in building engineering, and the design for special conditions or with specific requirements shall be carried out according to special requirements:

1 Brick masonry: including unreinforced and reinforced masonry of fired common brick, fired perforated brick, autoclaved sand-lime brick, autoclaved flyash-lime brick, common concrete brick and perforated concrete brick;

2 Block masonry: including unreinforced and reinforced masonry of concrete block and light aggregate concrete block;

3 Stone masonry: including masonry of various squared stones and rubbles.

1.0.3

This code is established according to the principle specified in the current national standard "Unified Standard Reliability Design of Building Structures" GB 50068. The design terms and symbols are adopted according to the requirements of the current national standard "Standard for Terminology and Symbols Used in Design of Building Structures" GB/T 50083.

1.0.4

For design according to this code, the load shall comply with the current national standard "Load Code for the Design of Building Structures" GB 50009; the selection and application of wall materials shall comply with the current national standard "Uniform Technical Code for Wall Material used in Buildings" GB 50574; the selection of concrete materials shall meet the requirements of the current national standard "Code for Design of Concrete Structures" GB 50010; the construction quality control shall meet the requirements of the current national standards "Code for Acceptance of Constructional Quality of Masonry Structures" GB 50203 and "Code for Acceptance of Constructional Quality of Concrete Structures" GB 50204; and the structural earthquake resistance design shall meet the relevant requirements of the current national standard "Code for Seismic Design of Buildings" GB 50011.

1.0.5

The masonry structure design shall not only comply with this code, but also those in the current relevant ones of the nation.

2.1 Terms

2.1.1 Masonry structure

Structure that wall and column built with block and mortar are used as the main loaded members of the building. It is the general term of brick masonry, block masonry and stone masonry structure.

2.1.2 Reinforced masonry structure

Structure that the reinforced masonry is used as the main loaded member of the building. It is the general term of mesh-reinforced masonry column, horizontal reinforced masonry wall, brick masonry and reinforced concrete layer or composite masonry column (wall) of reinforced mortar layer, composite wall of brick masonry and structural reinforced concrete column and reinforced concrete masonry shear wall structure.

2.1.3 Reinforced concrete masonry shear wall structure

Building structure composed of reinforced concrete masonry shear wall bearing vertical and horizontal action and concrete floor and roof.

2.1.4 Fired common brick

Roasted solid brick which takes coal gangue, shale, flyash or clay as the major raw materials, including fired coal gangue brick, fired shale brick, fired flyash brick, fired clay brick, etc.

2.1.5 Fired perforated brick

Fired brick that takes coal gangue, shale, flyash or clay as the major raw materials, with void ratio not greater than 35%, with small and more holes, and is mainly used for bearing position.

2.1.6 Autoclaved sand-lime brick

Solid brick which takes limy materials such as lime and siliceous materials such as sand as the major raw materials and is formed through blank preparation, pressing exhaust forming and autoclave curing.

2.1.7 Autoclaved flyash-lime brick

Solid brick which takes limy materials such as lime, slaked lime (carbide slag) or cement and siliceous materials such as flyash as well as aggregates (sand, etc.) as the major raw materials, adds an adequate amount of gypsum, and is formed through blank preparation, pressing exhaust forming and autoclave curing.

2.1.8 Concrete small hollow block

Hollow block which is made of ordinary concrete or light aggregate concrete, with a main dimension of 390mmx190mmx190mm and hollow ratio of 25%~50%, referred to as concrete block or masonry block.

2.1.9 Concrete brick

A perforated concrete half blind hole brick or solid brick which takes cement as cementitious material and sand, stone, etc. as the main aggregates and is made through mixing with water, forming and curing. The main dimensions of perforated bricks are 240mmx115mmx90mmm, 240mmx190mmx90mm, 190mmx190mmmx90mm, etc.; the main dimensions of solid bricks are 240mmx115mmx53mm, 240mmx115mmx90mm, etc.

2.1.10 Mortar for concrete small hollow block

Masonry mortar which is made by mechanically mixing such compositions as cement, sand, water and admixtures and additives added as required according to a certain proportion and is exclusively used for building concrete block, referred to as mortar for masonry block.

2.1.11 Grout for concrete small hollow block

Concrete which is made by mechanically mixing such compositions as cement, aggregate, water and admixtures and additives added as required according to a certain proportion and is used for concreting block masonry core column or other holes to be filled, referred to as block grout concrete.

2.1.12 Mortar for autoclaved silicate brick

Mortar which is made by mechanically mixing such compositions as cement, sand, water and admixtures and additives added as required according to a certain proportion and is exclusively used for building autoclaved lime-sand brick or autoclaved flyash brick masonry and the masonry shear strength shall not be less than the value of fired common brick masonry.

2.1.13 Pilastered wall

Buttressed wall which is formed by locally thickening the wall along the wall length direction at a certain interval.

2.1.14 Structural concrete column

Concrete column which is made according to the construction sequence of wall building first and then concrete column pouring based on structural reinforcement in the specified position of masonry building wall. Generally, it is referred to as structural concrete column, and structural column for short.

2.1.15 Ring beam

Sealed concrete beam member according to structural reinforcement, arranged along the horizontal direction of masonry wall at building eave, window top, storey, crane beam top or foundation top elevation.

2.1.16 Wall beam

Combined member composed of reinforced concrete joist and masonry wall within the range of calculation height on the beam, including simply-supported wall beam, continuous wall beam and frame-supported wall beam.

2.1.17 Cantilever beam

Cantilever reinforced concrete beam which is embedded in masonry. It general refers to balcony cantilever beam, awning cantilever beam or veranda cantilever beam in the building.

2.1.18 Design working life

Period specified in the design. During this period, the structure or structural member only needs normal maintenance for use according to its preset purpose, without overhaul reinforcement.

2.1.19 Static analysis scheme of building

Static analysis diagram of structure determined according to the space working performance of building. The static analysis scheme of building covers rigid analysis scheme, rigid-elastic analysis scheme and elastic analysis scheme.

2.1.20 Rigid analysis scheme

Static analysis scheme made for wall and column according to floor and roof as horizontally fixed hinged support.

2.1.21 Rigid-elastic analysis scheme

Static analysis scheme made for wall and column according to floor, roof and wall and column as hinged connection and in consideration of space working bent frame or frame.

2.1.22 Elastic analysis scheme

Scheme of static analysis for wall and column according to floor, roof and wall and column as hinged connection and without consideration of space working plane bent frame or frame.

2.1.23 Upper flexible and lower rigid complex multistorey building

Multistorey building that the top storey fails to meet the rigid analysis scheme requirements but the lower storeys meet the rigid analysis scheme requirements in structural analysis.

2.1.24 Types of roof or floor structure

Classification of roof and floor according to the structure detailing and corresponding rigidity of roof and floor. According to the common structure, the roof and floor may be divided into three types, but the horizontal rigidity of each type of roof and floor is approximately same.

2.1.25 Ratio of height to sectional thickness of wall or column

Ratio of calculation height to specified thickness of masonry wall and column. The specified thickness shall take the wall thickness for wall and the corresponding side length for column, and the sectional converted thickness for pilastered wall.

2.1.26 Effective support length of beam end

Distribution length of compressive stress of beam end on masonry or rigid cushion block interface along bean span direction.

2.1.27 Calculating overturning point

Rotating center taken as required for verifying the cantilever beam overturning resistance.

2.1.28 Expansion and contraction joint

Vertical joint with free expansion and contraction after the building is divided into two or several independent units, generally including double-wall expansion and contraction joint, double-column expansion and contraction joint, etc.

2.1.29 Control joint

Joint that the wall is divided into several independent wall limbs, and the wall limb is allowed with free deformation in its plane and has adequate resistivity against external force.

2.1.30 Category of construction quality control

Masonry construction quality control category divided according to quality assurance system of construction site, mortar and concrete strength, and comprehensive level of technical grade of masonry worker.

2.1.31 Confined masonry member

Masonry member which has restraint action by respectively arranging structural reinforced concrete column and ring-beam on both sides and upper and lower positions of unreinforced masonry wall piece for the purpose of increasing the ductility and resistance of unreinforced masonry wall piece.

2.1.32 Infilled wall in concrete frame structure

Wall which is built in frame structure.

2.1.33 Cavity wall filled with insulation

Wall that the continuous cavity reserved in the wall is filled with thermal insulating or heat insulating material and antirust metal tie is used to connect between interior side and exterior side of the wall.

2.1.34 Adjustable tie

Tie which is embedded in mortar joint of interior and exterior side of cavity wall filled with insulation and utilizes adjustable behavior to eliminate adverse effect generated by inconsistency of vertical deformation for interior and exterior side.

2.2 Symbols

2.2.1 Material property

MU - - Strength class of block;

M - - Strength class of common mortar;

Mb - - Strength class of mortar for concrete small hollow block;

Ms - - Strength class of mortar for autoclaved silicate brick;

C - - Concrete strength class;

Cb - - Strength class of grout for concrete small hollow block;

f1 - - Compressive strength class value or mean value of block;

f2 - - Compressive strength mean value of mortar;

f and fk - - Design value and characteristic value of compressive strength of masonry;

fg - - Design value of compressive strength of single-row hole and perforated concrete block grout masonry (referred to as design value of compressive strength of grout masonry);

fvg - - Design value of shear strength of single-row hole and perforated concrete block grout masonry (referred to as design value of shear strength of grout masonry);

ft and ft,k - - Design value and characteristic value of axial tensile strength of masonry;

ftm and ftm,k - - Design value and characteristic value of bending tensile strength of masonry;

fv and fv,k - - Design value and characteristic value of shear strength of masonry;

fVE - - Design value of earthquake resistance shear strength damaged along the stepped section of masonry;

fn - - Design value of compressive strength of mesh-reinforced brick masonry;

fy and - - Design value of tensile and compressive strength of steel bar;

fc - - Design value of axial compressive strength of concrete;

E - - Elastic modulus of masonry;

Ec - - Elastic modulus of concrete;

G - - Shear modulus of masonry.

2.2.2 Action and action effect

N - - Design value of axial force;

Nl - - Design value of axial force on local compression area and bearing pressure of beam end;

N0 - - Design value of upper axial force;

Nt - - Design value of axial tension;

M - - Design value of bending moment;

Mr - - Design value of anti-overturning moment of cantilever beam;

Mov - - Design value of overturning moment of cantilever beam;

V - - Design value of shear force;

F1 - - Design value of concentrated load on top of joist;

Q1 - - Design value of evenly distributed load on top of joist;

Q2 - - Design value of evenly distributed load on top of wall beam;

sigma0 - - Mean compressive stress of horizontal section.

2.2.3 Geometric parameters

A - - Sectional area;

Ab - - Area of cushion block;

Ac - - Sectional area of structural concrete column;

Al - - Local compression zone;

An - - Clear sectional area of wall;

A0 - - Calculation area affecting local compressive strength;

As and - - Sectional area of tensioned and compressed steer bar;

a - - Actual support length distance of side length and beam end;

ai - - Distance from opening side to the nearest support center of wall beam;

a0 - - Effective support length of beam end;

as and - - Distance from center of gravity of longitudinal tensioned and compressed steer bar to the proximal edge of cross section;

b - - Sectional width and side length;

bc - - Width of structural concrete column along wall length direction;

bf - - Calculated sectional flange width of pilastered wall and calculated width of wing wall;

- - Flange calculation width of T-shaped and inverse L-shaped sectional compression zone;

bs - - Door and window opening width within the distance range between adjacent transverse wall and wall between windows or between wall columns;

c and d - - Distance;

e - - Eccentricity of axial force;

H - - Wall height and member height;

Hi - - Storey height;

H0 - - Calculation height of member and calculation height of wall beam midspan section;

h - - Wall thickness, smaller side length of rectangular section, side length along eccentric axial force direction of rectangular section, sectional height;

hb - - Joist height;

h0 - - Effective height of section and converted height of cushion girder;

hT - - Converted thickness of T-shaped section;

hw - - Wall height and calculated sectional height of wall for wall beam;

l - - Spacing between structural columns;

l0 - - Calculation span of beam;

ln - - Clear span of beam;

I - - Sectional moment of inertia;

i - - Gyration radius of section;

s - - Spacing and sectional moment of area;

x0 - - Distance between calculating overturning point and outer edge of wall;

umax - - Maximum horizontal displacement;

W - - Section resistance moment;

y - - Distance from section gravity center to section edge of axial force in eccentric direction;

z - - Internal force arm.

2.2.4 Calculation coefficient

alpha - - Ratio of grout concrete area in block masonry to gross area of masonry, correction coefficient and coefficient;

alphaM - - Bending moment coefficient of joist in consideration of the combination action of wall beam;

beta - - Slenderness ratio of member;

[beta] - - Allowable slenderness ratio of wall and column;

betaV - - Shear coefficient of joist in consideration of the combination action of wall beam;

gamma - - Improvement coefficient of local compressive strength of masonry, coefficient;

gammaa - - Adjustment coefficient;

gammaf - - Partial coefficient of structural member property;

gamma0 - - Significance coefficient of structure;

gammaG - - Partial coefficient of permanent load;

gammaRE - - Earthquake resistance adjustment coefficient of bearing capacity;

delta - - Void ratio of concrete block, coefficient;

zeta - - Local compressive coefficient of masonry at the upper part of joist support;

zetac - - Participation service coefficient of core column;

zetas - - Participation service coefficient of steel bar;

etai - - Influence coefficient of space property of building;

etac - - Restraint correction coefficient of wall;

etaN - - Joist midspan axial force coefficient in consideration of the combination action of wall beam;

lambda - - Shear-span ratio of calculation section;

mu - - Correction coefficient, influence coefficient of composite shear and compressive force;

mu1 - - Correction coefficient of allowable slenderness ratio of self-bearing wall;

mu2 - - Correction coefficient of allowable slenderness ratio of wall with door and window opening;

muc - - Improvement coefficient of allowable slenderness ratio of wall arranged with structural column;

xi - - Relative height of sectional compression zone, coefficient;

xib - - Limit of relative height of compression zone;

xi1 - - Influence coefficient of wing wall or structural column to shear bearing capacity of wall for wall beam;

xi2 - - Influence coefficient of opening to shear bearing capacity of wall for wall beam;

rho - - Ratio of grouting and ratio of reinforcement of concrete masonry;

rhos - - Horizontal steel bar area ratio calculated according to vertical section of interlayer wall;

phi - - Influence coefficient of bearing capacity, coefficient;

phin - - Influence coefficient of bearing capacity of mesh-reinforced brick masonry member;

phi0 - - Stability coefficient of axial compression member;

phicom - - Stability coefficient of composite brick masonry member;

psi - - Reduction coefficient;

psiM - - Influence coefficient of opening to joist bending moment.

3.1 Strength Class of Materials

3.1.1

The strength class of bearing structure block shall be adopted according to the following requirements:

1 Strength class of fired common brick and fired perforated brick: MU30, MU25, MU20, MU15 and MU10;

2 Strength class of autoclaved sand-lime brick and autoclaved flyash-lime brick: MU25, MU20 and MU15;

3 Strength class of common concrete brick and perforated concrete brick: MU30, MU25, MU20 and MU15;

4 Strength class of concrete block and light aggregate concrete block: MU20, MU15, MU10, MU7.5 and MU5;

5 Strength class of stone: MU100, MU80, MU60, MU50, MU40, MU30 and MU20.

Notes: 1 The void ratio of light aggregate concrete block masonry with double-row hole or multi-row hole for bearing shall not be greater than 35%;

2 The folding-pressure ratio limit of perforated brick and autoclaved siliceous brick for bearing, the limit of void ratio, wall and rib dimension of perforated brick of non-sintered material for bearing as well as the carbonization and softening performance requirements shall meet the relevant requirements of the current national standard "Uniform Technical Code for Wall Material used in Buildings" GB 50574;

3 The specification, dimension and strength class of stone may be determined in accordance with the method in Appendix A of this code.

3.1.2

The strength class of hollow brick and light aggregate concrete block of the self-bearing wall shall be adopted according to the following requirements:

1 Strength class of hollow brick: MU10, MU7.5, MU5 and MU3.5;

2 Strength class of light aggregate concrete block: MU10, MU7.5, MU5 and MU3.5.

3.1.3

The strength class of mortar shall be adopted according to the following requirements:

1 Strength class of common mortar adopted by fired common brick, fired perforated brick, autoclaved sand-lime brick and autoclaved flyash-lime brick: M15, M10, M7.5, M5 and M2.5; strength class of dedicated masonry mortar adopted by autoclaved sand-lime brick and autoclaved flyash-lime brick masonry: Ms15, Ms10, Ms7.5 and Ms5.0;

2 Strength class of mortar adopted by common concrete brick, perforated concrete brick, concrete block with single-row hole and gangue concrete block masonry: Mb20, Mb15, Mb10, Mb7.5 and Mb5;

3 Strength class of mortar adopted by light aggregate concrete block masonry with double-row hole or multi-row hole: Mb10, Mb7.5 and Mb5;

4 Strength class of mortar adopted by untrimmed squared stone and rubble masonry: M7.5, M5 and M2.5.

Note: In determination of strength class of mortar, the block of the same kind shall be adopted as the bottom formwork of test block for mortar strength.