2.2　Symbols

2.2.1　Earthquake action and action effect:

F —Earthquake action of the electrical equipment（structure）；

m —Mass of the electrical equipment；

m _i —Mass concentrated at mass point i under operating conditions；

M —Bending moment；

T —Natural vibration period of the structure；

T _g —Characteristic period of ground motion；

σ —Tensile（compression）stress；

τ —Shear stress；

g —Acceleration of gravity.

2.2.2　Material performance

E —Modulus of elasticity of the material；

K —Lateral rigidity of the system；

σ —Tensile（compression）stress；

τ —Shear stress；

［ σ ］—Design allowable stress；

［ τ ］—Design allowable shear stress.

2.2.3　Geometric parameters:

A —Area of cross section；

d —ID of circumferential cross section；

D —OD of circumferential cross section；

H —Height of the structure；

H _i —Calculated height of mass point i ；

I —Second axial moment of area；

W —Modulus of section；

Z —Area moment of inertia.

2.2.4　The factors and coefficients used in calculations:

k —Unbalance factor；

α —Seismic influence factor；

α _max —Maximum seismic influence factor；

β —Floor dynamic magnification factor；

λ —Rigidity reduction coefficient；

r —Modal participation coefficient. LtED1lXLNzNFXCiqjWzN39eEY+vnSQDXotGMCevMwjDupWOAtu1Hm1uWkU2wuOgg