(1) In this Subsection,
Ar =response amplification factor to account for type of attachment of mechanical/electrical equipment, as defined in Sentence 4.1.8.18. (1),
Ax =amplification factor at level x to account for variation of response of mechanical/electrical equipment with elevation within the building, as defined in Sentence 4.1.8.18. (1),
Bx =ratio at level x used to determine torsional sensitivity, as defined in Sentence 4.1.8.11. (9),
B =maximum value of Bx, as defined in Sentence 4.1.8.11. (9),
Cp =seismic coefficient for mechanical/electrical equipment, as defined in Sentence 4.1.8.18. (1),
Dnx =plan dimension of the building at level x perpendicular to the direction of seismic loading being considered,
ex =distance measured perpendicular to the direction of earthquake loading between centre of mass and centre of rigidity at the level being considered,
Fa =site coefficient, as defined in Sentence 4.1.8.4. (7),
F(PGA) =site coefficient for PGA, as defined in Sentence 4.1.8.4. (5),
F(PGV) =site coefficient for PGV, as defined in Sentence 4.1.8.4. (5),
Fs =site coefficient, as defined in Sentence 4.1.8.1. (2),
F(T) =site coefficient for spectral acceleration, as defined in Sentence 4.1.8.4. (5),
Ft =portion of V to be concentrated at the top of the structure, as defined in Sentence 4.1.8.11. (6),
Fv =site coefficient, as defined in Sentence 4.1.8.4. (7),
Fx =lateral force applied to level x, as defined in Sentence 4.1.8.11. (6),
hi, hn, hx =the height above the base (i = 0) to level i, n, or x respectively, where the base of the structure is the level at which horizontal earthquake motions are considered to be imparted to the structure,
hs =interstorey height (hi - hi-1),
IE =earthquake importance factor of the structure, as described in Sentence 4.1.8.5. (1),
J =numerical reduction coefficient for base overturning moment, as defined in Sentence 4.1.8.11. (5),
JX =numerical reduction coefficient for overturning moment at level x, as defined in Sentence 4.1.8.11. (7),
Level i =any level in the building, i =1 for first level above the base,
Level n =level that is uppermost in the main portion of the structure,
Level x =level that is under design consideration,
Mv =factor to account for higher mode effect on base shear, as defined in Sentence 4.1.8.11. (5),
Mx =overturning moment at level x, as defined in Sentence 4.1.8.11. (7),
N =total number of storeys above exterior grade to level n,
=Average Standard Penetration Resistance for the top 30 m, corrected to a rod energy efficiency of 60% of the theoretical maximum,
PGA =Peak Ground Acceleration expressed as a ratio to gravitational acceleration, as defined in Sentence 4.1.8.4. (1),
PGAref =reference PGA for determining F(T), F(PGA) and F(PGV), as defined in Sentence 4.1.8.4. (4),
PGV =Peak Ground Velocity, in m/s, as defined in Sentence 4.1.8.4. (1),
PI =plasticity index for clays,
Rd =ductility-related force modification factor reflecting the capability of a structure to dissipate energy through reversed cyclic inelastic behaviour, as given in Article 4.1.8.9.,
Ro =overstrength-related force modification factor accounting for the dependable portion of reserve strength in a structure designed according to these provisions, as defined in Article 4.1.8.9.,
Rs =combined overstrength and ductility-related modification factor, as defined in Sentence 4.1.8.1. (7),
SP =horizontal force factor for part or portion of a building and its anchorage, as given in Sentence 4.1.8.18. (1),
S(T) =design spectral response acceleration, expressed as a ratio to gravitational acceleration, for a period of T, as defined in Sentence 4.1.8.4. (7),
Sa(T) =5% damped spectral response acceleration, expressed as a ratio to gravitational acceleration, for a period of T, as defined in Sentence 4.1.8.4. (1),
SFRS =Seismic Force Resisting System(s) is that part of the structural system that has been considered in the design to provide the required resistance to the earthquake forces and effects defined in Subsection 4.1.8.,
su =average undrained shear strength in the top 30 m of soil,
T =period in seconds,
Ta =fundamental lateral period of vibration of the building or structure in seconds in the direction under consideration, as defined in Sentence 4.1.8.11. (3),
Ts =fundamental lateral period of vibration of the building or structure in seconds in the direction under consideration, as described in Sentence 4.1.8.1. (7),
Tx =floor torque at level x, as defined in Sentence 4.1.8.11. (10),
TDD =Total Design Displacement of any point in a seismically isolated structure, within or above the isolation system, obtained by calculating the mean + (IE × the standard deviation) of the peak horizontal displacements from all sets of ground motion histories analyzed, but not less than × the mean, where the peak horizontal displacement is based on the vector sum of the two orthogonal horizontal displacements considered for each time step,
V =lateral earthquake design force at the base of the structure, as determined by Article 4.1.8.11.,
Vd =lateral earthquake design force at the base of the structure, as determined by Article 4.1.8.12.,
Ve =lateral earthquake elastic force at the base of the structure, as determined by Article 4.1.8.12.,
Ved =lateral earthquake design elastic force at the base of the structure, as determined by Article 4.1.8.12.,
VP =lateral force on a part of the structure, as determined by Article 4.1.8.18.,
Vs =lateral earthquake design force at the base of the structure, as determined by Sentence 4.1.8.1. (7),
=average shear wave velocity in the top 30 m of soil or rock,
W =dead load, as defined in Article 4.1.4.1., except that the minimum partition load as defined in Sentence 4.1.4.1. (3) need not exceed 0.5 kPa, plus 25% of the design snow load specified in Subsection 4.1.6., plus 60% of the storage load for areas used for storage, except that storage garages need not be considered storage areas, and the full contents of any tanks,
Wi, Wx =portion of W that is located at or is assigned to level i or x respectively,
WP =weight of a part or portion of a structure, e.g., cladding, partitions and appendages,
Wt =sum of Wi over the height of the building,
δave =average displacement of the structure at level x, as defined in Sentence 4.1.8.11. (9), and
δmax =maximum displacement of the structure at level x, as defined in Sentence 4.1.8.11. (9).