1 General provision
1.0.1 This specification is formulated to go through with national technical policy during design and construction of latticed shell and also achieve state-of-art technology, economy and rationality, safety and usability and guarantee quality.
1.0.2 This specification is applicable to design and construction of single-layer or double layer latticed shell composed by steel member bar.
1.0.3 Single-layer latticed shell should not be equipped with hanging crane. Double-layer latticed shell could directly bear up hanging crane load of A3 or higher grade. Fatigue computation shall be conducted when cycle index of stress variation is equal to or larger than 105 times, and its permissible stress amplitude and construction shall be determined through special test.
1.0.4 For design and construction of latticed shell, not only the requirements stipulated in this specification but also those in the current relevant ones of the nation shall be complied with.
2 Symbols
2.0.1 Action and action effect
FExji, FEyji, FEzji - Standard value of earthquake effect of j vibration mode and particle i respectively along direction x, y and z;
Gi - Typical value of gravity load of no.i joint;
g - Constant load acts on latticed shell;
M1, M2, M3 - Bending moment of latticed shell along direction 1, 2 and 3;
mx, my, mxy - Distributed moment and torque of imitative shell relative to axis X and Y;
N1, N2, N3 - Axial force of latticed shell along direction 1, 2 and 3;
nx, ny, nxy - Distributed axial force and shearing force of imitative shell relative to axis X and Y; ;
Nti, Nbi; Nci, Nvi - Axial force of top chord, bottom chord, web member and vertical rod of double-layer latticed shell;
NE - Axial force standard value of latticed shell' member bars under horizontal earthquake effect;
NG - Axial force standard value of latticed shell's member bars under typical gravity load;
NR - Design value of axial pressure bearing capacity or tensive capacity of hollow sphere;
Nbt - Design value of tensive capacity of high strength bolt;
[nks] - Permissible load standard value determined according to latticed shell stability;
q - Live load acts on latticed shell;
Rmax - Maximum support pressure caused by all load standard value on latticed shell;
SE - horizontal or vertical earthquake effect;
SEj - Effect of j vibration mode under horizontal or vertical earthquake effect;
Ui - Displacement component of joint i;
us - Horizontal displacement at support section;
Vi - Shearing force of joint i;
wm - Average compression deformation of rubber bearing pad;
θmax - Maximum turning of support.
2.0.2 Material property and structural member resistance
Be - Equivalent film rigidity;
Be11, Be22 - Equivalent film rigidity of latticed shell along direction 1, 2 and 3;
De - Equivalent bending rigidity;
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3 Basic requirements of design
3.0.1 Latticed shell shall be designed according to function and shape of building by comprehensively considering material supply and execution conditions as well as method of production and installation, and selecting rational roof type, boundary member and supporting structure for latticed shell so as to acquire favorable technical and economic effects.
3.0.2 Latticed shell may be build in single-layer or double-layer structure such as the following conventional types: cylindrical latticed shell, spherical latticed shell, elliptical parabolic latticed shell (double curved shell) and hyperbolic paraboloid latticed shell (saddle shaped latticed shell and torsional latticed shell).
3.0.3 Mesh of single-layer latticed shell may adopt the following conventional types.
1 Single-layer cylindrical latticed shell may adopt mesh such as:
— Unidirectional diagonal rod orthogonal spatial mesh (Figure 3.0.3-1a)
— Counter diagonal orthogonal spatial mesh (Figure 3.0.3-1b )
— Lamella mesh (Figure 3.0.3-1c)
— Three-way mesh (Figure 3.0.3-1d)
2 Single-layer spherical latticed shells may adopt mesh such as:
— Heel ring type (Figure 3.0.3-2a)
— Heel ring and diagonal rod type (Figure 3.0.3-2b)
— Three-way mesh (Figure 3.0.3-2c)
— Sector-shaped three-way mesh (Figure 3.0.3-2d)
— Sunflower-shaped three-way mesh (Figure 3.0.3-2e)
— Geodesic type (Figure 3.0.3-2f)
3 Single-layer elliptical parabolic latticed shells may adopt three-way (Figure 3.0.3 - 3a) or unidirectional diagonal rod orthogonal spatial mesh (Figure 3.0.3-3b)
4 Single-layer hyperbolic paraboloid latticed shell should adopt three-way mesh (Figure 3.0.3 - 4a), and mesh of two directions shall be distributed along straight burr; also may adopt two-way orthogonal mesh (Figure 3.0.3 - 4b) and distribute along principal direction of curvature; diagonal rod may be added if necessary.
3.0.4 When mesh of double-layer latticed shell is composed by two-way or three-way crossed girder units, they may be distributed with the method of article 3.0.3 of this specification. When double-layer latticed shell is composed by quadrangular pyramid and triangle pyramid units, they may be distributed with the method of article 3.0.3 of this specification.
