2.2　Symbols

2.2.1　Action and action effects

C——limit of crack width or deformation of structure or member；

fa——characteristic value of subgrade bearing capacity after correction；

P——design value of average compressive stress at the bottom surface of the foundation；

Pmax——design value of maximum compressive stress at the edge of bottom surface of the foundation；

R——design value of resistance of structural members；

SEhk——effect of characteristic value of horizontal seismic action；

SEQK——effect of representative value of the variable load of tensions of conductor and earthwire；

SEVK——effect of characteristic value of vertical seismic action；

SGE——effect of representative value of permanent load；

SGK——effect of characteristic value of permanent load；

SQiK——effect of characteristic value of variable load i；

SWK——effect of characteristic value of wind load；

T——maximum working load，line breakage load，string breakage load，check load or annual continuous load of insulator.

TE——design value of foundation uplifting or overturning forces；

Tmax——maximum tension at the lowest point of sag of conductor or earthwire；

TP——ultimate tensile force of conductor or earthwire；

TR——the rated mechanicalfailure load of insulator；

V——wind speed at the height of 10m above the ground；

WI——characteristic value of wind load of insulator string；

WO——characteristic value of reference wind pressure；

WS——characteristic value of tower wind load；

WX——characteristic value of horizontal w ind load perpendicular to the conductor and earthwire；

γS——design value of soil density；

γC——design value of concrete density.

2.2.2　Electrotechnical

n——number of pieces of insulators per insulator string in areas of altitude 1000m；

nH——number of pieces of insulators per insulator string in areas of high altitude；

U——system nominal voltage；

λ——specific creepage distance.

2.2.3　Calculation coefficient

B——magnification factor of wind load when coated with ice；

Ka——altitude correction factor for discharge voltage；

Kc——design safety factor of conductor or earthwire；

ke——effective coefficient of creepage distance of insulator；

ki——coefficient of suspension insulator string；

K1——safety factor of mechanical strength of insulators；

m——altitude correction factor；

m1——characteristic index；

α——nonuniformity coefficient of wind pressure；

βc——adjustment factor of wind load applied on conductor and earthwire；

βz——adjustment factor of tower wind load；

μs——shape factor of structural member；

μsc——shape factor of conductor or earthwire；

μz——height coefficient of wind pressure；

ψ——combination coefficient of variable loads；

ψWE——combination factor for wind loading in seismic basic combination；

γo——importance factor of tower structure；

γEh——partial factor of horizontal seismic action；

γEV——partial factor of vertical seismic action；

γEQ——integration by partial factors for variable loads of tension of conductor and earthwire；

γG——partial factor for permanent load；

γQi——partial factor for variable load i；

γrf——adjustment factor for bearing capacity of subgrade；

γRE——adjustment factor for seismic capacity；

γf——additional partial factor for foundation.

2.2.4　Geometric parameters

AI——calculated wind pressure bearing area of insulator string；

AS——calculated projected area of wind pressure bearing part of member；

D——horizontal clearance between phase conductors；

Dp——horizontal projection clearance between conductors；

Dx——equivalent horizontal clearance between conductors arranged in triangular configuration；

Dz——vertical projection clearance between conductors；

d——conductor or earthwire diameter or the calculating diameter thereof when coated with ice；it shall be the sum of the outer diameters of all sub-conductors for bundle conductors；

fc——maximum sag of conductor；

H——altitude above sea level；

L——span length；

Lk——length of suspension insulator string；

Lol——geometric creepage distance of monolithic suspension insulator；

Lp——horizontal spanlength of towers；

S——clearance between conductor and earthwire；

θ——angle between the wind direction and direction of conductor or earthwire；

γk——characteristic value of geometric parameter.