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.
This code is established according to requirements of Notice on Issuing Plans for Design and Amendment to 1998 Engineering Construction Standard (first) (JIANBIAO [1998] NO.94, issued by Ministry of Construction P.R.C., and is extensively revised by China Northeast Architectural Design & Research Institute and relevant design, research and education organizations.
During the revision, relevant organizations executed monographic study and extensive investigation on the codes, summarized scientific research achievements and engineering experiences accumulated in recent years, considered economic condition and engineering practices in China, ask for suggestions from relevant organizations. The final piece is reviewed and determined by Standard and Quota Department under Ministry of Construction P.R.C. after extensive discussion, amendment, supplement and try design. The revision covers ten chapters and five appendixes.
This code may be further revised partially in the future and relevant revision will be published on magazine standardization of Engineering Construction.
Chapter 1 General Provisions
Article 1.0.1 This code is established for the purpose of executing technical and economic policies in China, adhering to principles of adjusting measures to local conditions and using local materials, so as to realize choosing appropriate structural methods and materials, to adopt advanced techniques and economic measures and to guarantee construction quality.
Article 1.0.2 The code is applicable to following structural design of masonry in architectural engineering, but specified provisions shall be observed is there are special conditions or requirements.
1. Brick masonry, including reinforced or non-reinforced masonry built of fired common brick, fired perforated brick, autoclaved sand-lime brick and autoclaved flyash-lime brick;
2. Concrete block masonry, including reinforced or non-reinforced masonry built of concrete and light-bone-material concrete block masonry;
3. Stone masonry, including all sorts of squared stone and rubble stone masonry.
Article 1.0.3 This code is designed according to principles of applicable Unified Standard for Reliability Design of Building Structures GB 50068-2001. Design terminology and symbols in this code are compliant with provisions of Standard for Terminology and Symbols Used in Design of Building Structures GB/T 50083.
Article 1.0.4 If this code is applied in design, load shall be executed according to provisions of Load Code for the Design of Building Structures GB 50009; quality of material and construction shall be compliant with provisions of Code for Design of Concrete Structures GB 50010-2002, Code for Acceptance of Construction Quality of Masonry Engineering GB 50203-2002 and Code for Acceptance of Concrete Structure Quality GB 50204; structural seismic design shall also be compliant with provisions described in Code for Seismic Design of Buildings GB 50011.
Article 1.0.5 Besides requirements in this code, structural design of masonry shall also be compliant with provisions described in relevant standards and codes.
Chapter 2 Terms and signs
2.1 Main terms
Article 2.1.1 masonry structure
Masonry structure means structures that are used as main load-bearing members in a building, such as blocks or mortar walls or columns. This term is a general designation for masonry structures of brick or stone.
Article 2.1.2 reinforced masonry structure
Reinforced masonry structure means structures whose main load-bearing members are masonries with reinforced steel. It is a general designation for web-reinforcement masonry column, level reinforced masonry wall, masonry column (wall) build with brick masonry and reinforced concrete or reinforced mortar, compound wall build with brick masonry and reinforced structural concrete column and reinforced concrete masonry shear wall structure.
Article 2.1.3 reinforced concrete masonry shear wall structure
Reinforced concrete masonry shear wall structure means constructional structure build with reinforced masonry shear wall that bears vertical and level loading and concrete building and roof.
Article 2.1.4 fired common brick
Fired common brick means solid bricks whose perforation ratio is less or equal to the stipulated value and physical dimension is compliant with provisions, fired with main raw materials such as clay, shale, coal gangue or flyash. They are classified into fired clay brick, fired shale brick, fired coal gangue brick and fired flyash brick, etc.
Article 2.1.5 fired perforated brick
Fired perforated bricks are divided into P-type brick and M-type brick, both of which are mainly fired with clay, shale, coal gangue or flyash. Their perforation ratio is greater or equal to 25%; perforation is small in size but large in quantity. They are mainly used in bearing section of a building.
Article 2.1.6 autoclaved sand-lime brick
Autoclaved sand-lime brick are solid bricks that are mainly fired with lime and sand through blank-preparation, shape-pressing and steaming-pressure maintenance. They are also called sand-lime brick for short.
Article 2.1.7 autoclaved flyash-lime brick
Autoclaved flyash-lime bricks are solid bricks that are fired with flyash, lime, ratiod gupsum and cumulated materials through blank-preparing, shape-pressing and high-pressure-steam-maintaining. They are also called flyash brick for short.
Article 2.1.8 concrete small hollow block
Concrete small hollow blocks are hollow blocks fired with common concrete or aggregate concrete. Their main size is 390mm×190mm×190mm; hollowness ratio is 25%-50%. They are also called concrete brick or concrete block for short.
Article 2.1.9 mortar for concrete small hollow block
Mortars for concrete small hollow blocks are mortar masonries that are fired with mixtures of cement, sand, water, and ratiod blending and additives through mechanical mixing. They are mainly used for making concrete block, also called for masonry-special mortar.
Article 2.1.10 grout for concrete small hollow block
Grout for concrete small hollow blocks is fired with cement, aggregate, water and ratiod blending and additives through mechanical mixing. They are mainly used for casting concrete masonry core columns or other concrete that needs perforation filling. They are also called masonry perforation-filling concrete for short.
Article 2.1.11 Pilastered wall
Pilastered walls are stiffening walls that are partial thickened along wall length in certain interval.
Article 2.1.12 rigid transverse wall
Rigid transverse wall means transverse walls whose rigidity and bearing capacity in masonry structure are compliant with provisions. Rigid transverse walls are also called transverse-stabilizing structure.
Article 2.1.13 cavity wall filled with insulation
Cavity wall filled with insulation means walls that are filled with insulation in reserved successive cavity inside wall and connected between internal wall and external wall with rustproof metal anchor.
Article 2.1.14 structural concrete column
Structural concrete column is concrete column which is build at specified parts of wall and is reinforced according to structure, with a wall-to-casting-concrete constructional sequence. They are usually called structural concrete column and are also called structural column for short.
Article 2.1.15 ring beam
Ring beam means reinforced and closed concrete beams that are casted along level direction of masonry wall at specified height of cornice, up window frame, floor, peak or base of crane beam.
Article 2.1.16 wall beam
Wall beam is a kind of support member composed of reinforced concrete girder and masonry walls within calculated height on reinforced concrete girder. Wall beams include simply supported wall beam, successive wall beam and frame supported wall beam.
Article 2.1.17 cantilever beam
Cantilever beams are overhanging reinforced concrete beams that are embedded in masonry. Generally, cantilever beam means balcony cantilever beam, awning cantilever beam or external corridor cantilever beam.
Article 2.1.18 design working life
Design working life means design-specified term, during which structure and structural member could be properly used with only common maintenance, but not with special procedures.
Article 2.1.19 static analysis scheme of building
Static analysis scheme of building is a structural static analysis scheme determined according to space performance of house. It mainly includes rigid analysis scheme, rigid-elastic analysis scheme and elastic analysis scheme.
Article 2.1.20 rigid analysis scheme
Rigid analysis scheme is a scheme for calculating static force of wall and column provided that roof and floor are level immobile hinged support.
Article 2.1.21 rigid-elastic analysis scheme
Rigid-elastic analysis scheme is a scheme for calculating static force of wall and column provided that roof and floor are hinge-connected with consideration of support or frame space.
Article 2.1.22 elastic analysis scheme
Elastic analysis scheme is a scheme for calculating static force of wall and column provided that roof and floor are hinge-connected with wall and column, without considering plane support or frame space.
Article 2.1.23 upper flexible and lower rigid complex multi-storey building
In structural schemes, this term means multi-storey building whose upper storey is compliant with rigid analysis scheme requirements, but lower storeys are compliant.
Article 2.1.24 types of roof or floor structure
This term means classification of roof or floor structures according to their structural constructions and homologous rigidity. According to their general structures, roofs and floors may be divided into three kinds whose level stiffness is almost identical.
Article 2.1.25 ratio of height to sectional thickness of wall or column
This term is a ratio of calculated height to specified thickness of masonry wall or column. Specified thickness is a converted thickness through wall thickness, corresponding side length of column and sectional area of pilastered wall.
Article 2.1.26 effective support length of beam end
This term means distribution length of pressure stress on interface of masonry or rigidity cushion block along beam span direction.
Article 2.1.27 calculating overturning point
This term means rotary center that is selected when checking antidumping of cantilever beam according to provisions.
Article 2.1.28 expansion and contraction joint
This term means vertical joint among units that are separated from building and can expand and contract freely. Joints of this kind are generally divided into double-wall expansion and contraction joint and double-column expansion and contraction joint, etc.
Article 2.1.29 control joint
This term means structural joints that are set at positions where stress of wall is relatively concentrated or vertical mortar joints of wall are same, allowing free wall-change and having adequate resistance to exterior force.
Article 2.1.30 category of construction quality control
This term means masonry constructive quality control levels that are set according to general level of quality-guarantee system on site, intensity of mortar and concrete and masonry worker's technical grade.
2.2 Signs
Article 2.2.1 Material performance
MU----intensity grade of block
M----intensity grade of mortar
Mb----intensity grade of mortar for concrete small hollow block
C----intensity grade of concrete
Cb----intensity grade of grout for concrete small hollow block
f1----intensity grade value or average value of block
f2----average value of anti-pressure intensity of mortar
f, fk----design value of anti-pressure intensity or standard value of masonry
fg----anti-pressure design value of aperture-casted concrete masonry masoned with single line aperture and opposite aperture (design value of anti-pressure intensity of aperture-casted masonry for short)
fvg----anti-shear intensity design value of aperture-casted concrete masonry masoned with signle line aperture and opposite aperture (anti-shear intensity design value of aperture-casted masonry for short)
ft, ft,k----masonry design value or standard value of axial anti-stress intensity
ftm, ftm,k----masonry design value or standard value of bend anti-stress intensity
fv, fv,k----masonry design value or standard value of anti-shear intensity
fVE----masonry design value of anti-shake intensity along damage of step section
fn---- design value of anti-pressure intensity of web reinforced masonry
fy, f'y---- design value of anti-stress and anti-pressure intensity of steel bar
fc---- design value of axial anti-pressure intensity of concrete
E----elastic modulus of masonry
EC----elastic modulus of concrete
G----shear modulus of masonry
Article 2.2.2 Action and action effect
N---- design value of axial force
Nι---- design value of axial force on partial compression area
N0---- design value of upper axial force
Nt---- design value of axial tension
M---- design value of bend span
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 loading on top of joist
Q1---- design value of even-distributed loading on top of joist
Q2---- design value of eve-distributed loading on top of wall beam
σ0----average pressure stress on level section
Article 2.2.3 Geometric Parameter
A----sectional area
Ab----area of cushion block
AC----sectional area of structural concrete column
Aι----partial compression area
An----net sectional area of wall
A0----calculating area affecting partial anti-pressure intensity
As, A's----sectional area of tensioned or pressed steel bar
a----actual supporting length and distance of side line and beam end
ai----distance from aperture opening to the nearest supporter center of wall beam
a0----effective supporting length of beam end
as, a's----distance from center of gravity of vertical tensioned and pressed steel bar to near side of section
b----sectional width or side length
bc----width of structural concrete column along wall direction
bf----calculated sectional edge width or calculated side wall width of pilastered wall
b'f----calculated edge width in pressed T-type or reversed-L-type section
bs----width of door or window opening among bordered transverse walls, among walls between windows or among pilastered walls
c, d----distance
e----eccentric distance of axial force
H----height of wall or component
Hi----storey height
H0----sectional height of component, calculated height of wall beam crossing middle section
h----wall thickness, less side length of rectangular section, side length along eccentric axial force direction of rectangular section, sectional height
hb----joist height
h0----effective sectional height, converted height cushion girder
hT----converted height of T-type section
hW----wall height, calculated sectional height of wall beam
ι----space among structural column
ι0----calculated span of beam
ιn----net span of beam
I----sectional moment of inertia
i----sectional radius of gyration
s----space, sectional moment of area
xo----distance between calculating overturning point and outer edge of wall
umax----maximum horizontal displacement
W----sectional resistive moment
y----distance between sectional gravity center and eccentric sectional edge of axial direction
z----internal moment arm
Article 2.2.4 Calculated Coefficient
α----ratio of grout concrete area to gross masonry area of concrete block masonry, modification coefficient, coefficient
αM----bend moment coefficient of joist with consideration of combined effect of wall beam
β----height-to-thickness ratio of component
[β]----allowable height-to-thickness ratio of wall or column
βV----coefficient of joist shear force with consideration of wall beam combined effect
γ----increasing coefficient of partial anti-pressure intensity of masonry
γa----adjustment coefficient
γf----partial coefficient of material performance of structural component
γ0----coefficient of structural importance
γRE----aseismic adjustment coefficient of loading capacity
δ----perforation ratio or coefficient of concrete block masonry
ζ----partial pressure coefficient of masonry on upper side of joist bearing
ζc----participation coefficient with participation of core column
ζs----participation coefficient with participation of steel bar
ηi----coefficient influencing space performance of building
ηc----modification coefficient of wall restriction
ηN----medial-axis-force-span coefficient of joist with consideration of combined effect of wall beam
λ----shear-span ratio of calculated section
μ----modification coefficient, coefficient influencing shear-pressure composite force
μ1----modification coefficient of self-bearing wall with allowable height-to-thickness ratio
μ2----modification coefficient of door and window walls with allowable height-to-thickness ratio
μc----increasing coefficient structural column wall with allowable height-to-thickness ratio
ξ----relative height or coefficient of sectional compression area
ξb----limited value of relative height of compression area
ξ1----shear effect coefficient of beam wall shear loading capacity produced by wing wall or structural column
ξ2----shear effect coefficient of hole on beam wall
ρ----grouting ratio of concrete block masonry or reinforcement ratio
ρs----area ratio of horizontal steel bar calculated according to vertical section among storeys
φ----coefficient or effect coefficient of loading force
φn----effect coefficient of loading force of web reinforced brick masonry components
φ0----stable coefficient of axial compression components
φcom----stable coefficient of combined brick masonry components
Ψ----reduced coefficient
ΨM----effect coefficient of hole-to-joist bend moment
Chapter 3 Material
3.1 Material intensity grades
Article 3.1.1 Intensity grade of block masonry and mortar shall be compliant with the following provisions:
1. Intensity grade of fired common brick and fired perforated brick: MU30, MU25, MU20, MU15 and MU10;
2. Intensity grade of autoclaved sand-lime brick, autoclaved flyash-lime brick: MU25, MU20, MU15 and MU10;
3. Intensity grade of block masonry: MU20, MU15, MU10, MU7.5 and MU5;
4. Intensity grade of stone material: MU100, MU80, MU60, MU50, MU40, MU30 and MU20;
5. Intensity grade of mortar: M15, M10, M7.5, M5 and M2.5.
Notes:
1. Specification, size and intensity grade of stone materials may be determined according to Appendix A of this code;
2.When determining intensity grade of autoclaved flyash-lime brick or concrete block masonry mixed with over 15% flyash, corresponding anti-pressure intensity shall multiply natural carbonization coefficient; if no natural carbonization coefficient is available, 1.15 times of manual carbonization coefficient may be adopted;
3. When determining intensity grade of mortar, block of the same type as mortar block shall be adopted as test bottom module.
3.2. Calculating indexes of masonry
Article 3.2.1 For design value of anti-pressure intensity of all types of masonry whose life is 28d calculated according to gross section, if category of construction quality control is grade B, following provisions shall be adopted respectively according to corresponding intensity grade of block masonry or mortar:
1. Design value of anti-pressure intensity of fired common brick masonry and fired perforated brick masonry shall be calculated according to Table 3.2.1-1.
2. Design value of anti-pressure intensity of autoclaved sand-lime brick masonry and autoclaved flyash-lime brick masonry shall be calculated according to Table 3.2.1-2.
Design value of anti-pressure intensity of fired common brick and fired perforated brick masonry (MPa) Table 3.2.1-1
Intensity grade of brick Intensity grade of mortar Mortar strength
M15 M10 M7.5 M5 M2.5 0
MU30 3. 94 3. 27 2. 93 2. 59 2. 26 1. 15
MU25 3. 60 2. 98 2. 68 2. 37 2. 06 1. 05
MU20 3. 22 2. 67 2. 39 2. 12 1. 84 0. 94
MU15 2. 79 2. 31 2. 07 1. 83 1. 60 0. 82
MU10 -- 1. 89 1. 69 1. 50 1. 30 0. 67
Design value of anti-pressure intensity of autoclaved sand-lime brick masonry and autoclaved flyash-lime brick masonry (MPa) Table 3.2.1-2
Intensity grade of brick Intensity grade of mortar Mortar strength
M15 M10 M7.5 M5 0
MU25 3. 60 2. 98 2. 68 2. 37 1. 05
MU20 3. 22 2. 67 2. 39 2. 12 0. 94
MU15 2. 79 2. 31 2. 07 1. 83 0. 82
MU10 -- 1. 89 1. 69 1. 50 0. 67
3. Design value of anti-pressure intensity of single-rang-hole concrete masonry and light-bone-material-concrete block masonry shall be calculated according to Table 3.2.1-3.
Design value of anti-pressure intensity of single-rang-hole concrete masonry and light-bone-material-concrete block masonry (MPa) Table 3.2.1-3
Intensity grade of block masonry Intensity grade of mortar Mortar strength
Mb15 Mb10 Mb7.5 Mb5 0
MU20 5. 68 4. 95 4. 44 3. 94 2. 33
MU15 4. 61 4. 02 3. 61 3. 20 1. 89
MU10 -- 2. 79 2. 50 2. 22 1. 31
MU7.5 -- -- 1. 93 1. 71 1. 01
MU5 -- -- -- 1.19 0. 70
Notes:
1 For hole-interlaced masonry, values listed in this table shall be multiplied by 0.8;
2 Fro concrete block masonry of independent column or double-line thickness, values listed in this table shall be multiplied by 0.7;
3 For masonry of T-type section, values listed in this table shall be multiplied by 0.85;
4 Light-bone-material concrete block masonry in this table means coal gangue and cement-cinder concrete block masonry.
4. For single-range hole-to-hole concrete block masonry, design value of anti-pressure intensity of grouted masonry shall be calculated according to following formulas:
fg＝f+0. 6αfc (3.2.1-1)
α＝δρ (3.2.1-2)
Where, s:
fg----design value of anti-pressure intensity of grouted masonry, not exceeding 2 times design value of non-grouted masonry;
f----design value of anti-pressure intensity of non-grouted masonry, according to Table 3.2.1-3;
fc----design value of axial anti-pressure intensity of grout concrete;
α----ratio of grout concrete area to gross masonry area in concrete block masonry;
δ----perforation ratio of concrete block masonry;
ρ----grouting ratio of concrete block masonry. It is also the ratio of sectional grout concrete area to sectional perforation area. It shall not be less than 33%.
Grout concrete intensity grade of concrete block masonry shall not be less than Cb20, and not be 2 times less than block intensity grade.
Notes: intensity grade of grout concrete Cb×× is equal to intensity standard of corresponding concrete intensity grade C××.
5. Design value of anti-pressure intensity of double rang holes or multiple rang holes light-bone-material-concrete block masonry with perforation ratio not greater than 35% shall be calculated according to Table 3.2.1-5.
6. Design value of anti-pressure intensity of rubble stone masonry 180~350mm high shall be calculated according to Table 3.2.1-6.
Light-bone-material-concrete block masonry的 design value of anti-pressure intensity (MPa) Table 3.2.1-5
Intensity grade of block masonry Intensity grade of mortar Mortar strength
Mb10 Mb7.5 Mb5 0
MU10 3.08 2.76 2.45 1.44
MU7.5 -- 2.13 1.88 1.12
MU5 -- -- 1.31 0. 78
Notes:
1 Masonries that are mentioned in this Table means cinder, pumice and pottery grain light-bone-material-concrete block masonry;
2 Design valve of anti-pressure intensity of light-bone-material-concrete block masonry whose thickness is double ranges masonry shall be calculated according to 80% of values listed in this Table.
Design value of anti-pressure intensity of rubble stone masonry (MPa) Table 3.2.1-6
Intensity grade of rubble stone Intensity grade of mortar Mortar strength
M7.5 M5 M2.5 0
MU100 5.42 4.80 4.18 2.13
MU80 4.85 4.29 3.73 1.91
MU60 4.20 3.71 3.23 1.65
MU50 3.83 3.39 2.95 1.51
MU40 3.43 3.04 2.64 1.35
MU30 2.97 2.63 2.29 1.17
MU20 2.42 2.15 1.87 0. 95
Notes:
For following masonries, corresponding coefficients shall be multiplied:
fine stone masonry 1.5
semi-fine stone masonry 1.3
rubble stone masonry 1.2
dry-laid stone masonry 0. 8
7. Design value of anti-pressure intensity of rubble stone masonry shall be calculated according to Table 3.2.1-7.
Design value of anti-pressure intensity of rubble stone masonry (MPa) Table 3.2.1-7
Intensity grade of rubble stone Intensity grade of mortar Mortar strength
M7.5 M5 M2.5 0
MU100 1.27 1.12 0. 98 0. 34
MU80 1.13 1.00 0. 87 0. 30
MU60 0. 98 0. 87 0. 76 0. 26
MU50 0. 90 0. 80 0. 69 0. 23
MU40 0. 80 0. 71 0. 62 0. 21
MU30 0. 69 0. 61 0. 53 0. 18
MU20 0. 56 0. 51 0. 44 0. 15
Article 3.2.2 If construction quality control is grade B, design value of all kinds of masonry, whose life term is 28 days, calculated through gross section, including design value of axial tensile strength, bend tensile strength and shear strength shall be calculated according to Table 3.2.2.
Design value of axial tensile strength, bend tensile strength and shear strength when sections along mortar joints are damaged (MPa) Table 3.2.2
Strength type Damage feature and masonry type Intensity grade of mortar
≥M10 M7.5 M5 M2.5
axial tensile strength along teeth joints
fired common brick, fired perforated brick
autoclaved sand-lime brick，autoclaved flyash-lime brick
concrete block masonry
rubble stone 0. 19
0. 12
0. 09
0. 08 0. 16
0. 10
0. 08
0. 07 0. 13
0. 08
0. 07
0. 06 0. 09
0. 06
0. 04
bend tensile strength along teeth joints
fired common brick, fired perforated brick
autoclaved sand-lime brick，autoclaved flyash-lime brick
concrete block masonry
rubble stone 0. 33
0. 24
0. 11
0. 13 0. 29
0. 20
0. 09
0. 11 0. 23
0. 16
0. 08
0. 09 0. 17
0. 12
0. 07
along joints
fired common brick, fired perforated brick
autoclaved sand-lime brick，autoclaved flyash-lime brick
concrete block masonry 0. 17
0. 12
0. 08 0. 14
0. 10
0. 06 0. 11
0. 08
0. 05 0. 08
0. 06
shear strength fired common brick, fired perforated brick
autoclaved sand-lime brick，autoclaved flyash-lime brick
concrete and light-bone-material concrete block masonry
rubble stone 0. 17
0. 12
0. 09
0. 21 0. 14
0. 10
0. 08
0. 19 0. 11
0. 08
0. 06
0. 16 0. 08
0. 06
0. 11
Notes:
1 If ratio of lap-joint length to block height is less than 1, design value of axial tensile strength (ft) and bend tensile strength (ftm) of masonries build with blocks of regular shape shall be calculated according to result of values in this table multiplying ratio of lap-joint length to block height;
2 Shear strength design value of double rang holes or multiple rang holes light-bone-material concrete block masonry whose perforation ratio not exceeds 35% may be calculated according to result of concrete block masonry shear strength design value in this table multiplying 1.1;
3 If reliable test data are available, design value of autoclaved sand-lime brick and autoclaved flyash-lime brick masonry may be changed appropriately;
4 If reliable test data are available, design value of fired shale brick, fired coal gangue brick and fired flyash brick masonries may be changed appropriately.
Shear strength design value (fvg) of grouted masonries that are built with single-range hole-to-hole concrete block masonry shall be calculated according to the following formula:
fvg＝0. 2f0. 55g (3.2.2)
Where
fg----anti-pressure intensity design value of grouted masonry (MPa).
Article 3.2.3 Intensity design values of following masonries shall multiply adjustment coefficient (γa):
1 For crane-building masonry, under-beam fired common brick masonry with span not less than 9m, under-beam fired perforated brick, autoclaved sand-lime brick and autoclaved flyash-lime brick masonries with span not less than 7.5m, γa shall be 0.9;
2 For masonry members，if their sectional area is less than 0.3m2, γa shall be sectional area plus 0.7. For reinforced masonry members, if their sectional area is less than 0.2m2, γa shall be sectional area plus 0.8. Sectional area of member shall be calculated according to m2;
3 If masonry is built with cement mortar, for values described in Article 3.2.1, γa shall be 0.9; for values described in Table 3.2.2 of Article 3.2.2, γa shall be 0.8; for reinforced masonry members, if they are built with cement mortar, only masonry strength design value multiple adjustment coefficient γa;
4 If construction quality control is grade C, γa shall be 0.89;
5 When checking building members under construction, γa shall be 1.1.
Notes: construction quality control of reinforced masonry shall not be grade C.
Article 3.2.4 During construction, strength and reliability of newly built masonry whose mortar hasn’t hardened may be calculated under assume that mortar strength is zero.
For masonries that are built by adding salt in winter, if intensity of mortar built under usual temperature increases one grade higher, intensity and stability of masonry need not be checked.
Notes: reinforced masonry shall not use salt-added mortar.
Article 3.2.5 Elastic modulus of masonry, line expansion coefficient, shrinkage coefficient and wearing coefficient may be calculated according to values listed in Table 3.2.5-1, 3.2.5-2 and 3.2.5-3. Shear modulus of masonry may be calculated according to 40% elastic modulus of masonry.
1 Elastic modulus of masonry may be calculated according to Table 3.2.5-1.
elastic modulus of masonry (MPa) Table 3.2.5-1
masonry type Intensity grade of mortar
≥M10 M7.5 M5 M2.5
fired common brick and fired perforated brick masonry 1600f 1600f 1600f 1390f
autoclaved sand-lime brick and autoclaved flyash-lime brick masonry 1060f 1060f 1060f 960f
concrete block masonry 1700f 1600f 1500f --
rough stone, rubble stone, rubble stone masonry 7300 5650 4000 2250
fine stone and semi-fine stone masonry 22000 17000 12000 6750
Notes:
Elastic modulus of light-bone-material-concrete block masonry may be calculated according to elastic modulus of concrete block masonry listed in the table.
Elastic modulus of concrete grouted masonry built by single-range hole-to-hole method shall be calculated according the following formula:
E＝1700fg (3.2.5-1)
Where, ,
fg----design value of anti-pressure intensity of grouted masonry
2 Line expansion coefficient and shrinkage rate of masonry may be calculated according to Table 3.2.5-2.
line expansion coefficient and shrinkage rate of masonry Table 3.2.5-2
masonry type line expansion coefficient
10-6/℃ shrinkage rate
mm/m
fired clay brick masonry 5 -0. 1
autoclaved sand-lime brick and autoclaved flyash-lime brick masonry 8 -0. 2
concrete block masonry 10 -0. 2
Light-bone-material-concrete block masonry 10 -0. 3
Stone and rubble stone masonry 8 --
Notes:
Shrinkage rate listed in the table is applicable to block masonry whose shrinkage reaches allowable standard after 28 days. Reliable local test data may be used, if they are available.
3 Table 3.2.5-3 Friction coefficient of masonry
friction coefficient Table 3.2.5-3
material type type of friction surface
dry Wet
Masonry slides on masonry or concrete 0. 70 0. 60
Wood block slides on masonry 0. 60 0. 50
Steel slides on masonry 0. 45 0. 35
Masonry slides on mortar or scree 0. 60 0. 50
Masonry slides on powder soil 0. 55 0. 40
Masonry slides on cohesive soil 0. 50 0. 30
Chapter 4 Basic design provisions
4.1 Design principle
Article 4.1.1 In this code, calculation is processed according to limit-state design method based on probability theory, reliability of structural member measured with reliable index and design expression formula of partial coefficient.
Article 4.1.2 Masonry structure shall be designed according to limit state of bearing capacity, and satisfy limit-state requirements under normal use.
Notes: generally, according to constructional features of masonry, corresponding structural measures may guarantee limit-state requirements of masonry structure under normal use.
Article 4.1.3 Masonry structure and structural member must be ready for use within working life with normal maintenance, but need not special repair. Design working life of masonry may be determined according to Unified standard for reliability design of building structures GB 50068-2001.
Article 4.1.4 Based on severity of results (harm to life, economic losses or social impact) that may be caused by structural damage, building structure shall be divided into three security grade according to Table 4.1.4, and proper grade shall be followed in practical conditions.
security grade of building structure Table 4.1.4
security grade Damage result Building type
Grade one Very severe Important building
Grade two severe Common building
Grade three Not severe Lesser building
Notes:
1 Security grade of special building may be determined according to practical conditions.
2 Structural designs of masonry in seismic area shall be compliant with applicable Standard for Classification of Seismic Protection of Buildings GB50223, according to importance of building.
Article 4.1.5 If masonry structure is designed according to limit-state bearing capacity, the worst formula below shall be adopted:
Where,
γ0----structural importance coefficient. For structural members of grade one or structural members whose design working life is 50 years, γ0 shall not be less than 1.1; for structural members of grade two or structural members whose design working life is 50 years, γ0 shall not be less than 1.0; for structural members of grade three or structural members whose design working life is 1-5 years, γ0 shall not be less than 0.9;
SGk----efficiency of characteristic value of pamanent load;
SQ1k----efficiency of characteristic value of variable load exerting control affect in basic combination;
SQik----efficiency of characteristic value variable load (i);
R (·)----forcing function of structural member;
γQi----partial coefficient of variable load (i);
Ψci----combined value coefficient of variable load (i). Generally, Ψci shall be 0.7; for book store, archives store, storeroom, ventilation machine room and elevator machine room, Ψci shall be 0.9;
f----design value of masonry strength, f＝fk/γf;
fk----characteristic value of masonry strength, fk＝fm-1.645σf;
γf----partial coefficient of material performance in masonry structure. Generally, if construction control is grade B, γf shall be 1.6; if construction control is grade B, γf shall be 1.8;
fm----average value of masonry strength;
σf----standard deviation of masonry strength;
ak----characteristic value of geometric parameter.
Notes: 1 if characteristic value of live load is greater than 4kH/m2, coefficient where, shall be 1.3;
2 Division of construction quality control categories shall be compliant with provisions of Code for acceptance of construction quality of masonry engineering GB50203.
Article 4.1.6 If stability of masonry structure is calculated as a whole, such as overturn, slide or float, the following formula shall be used:
