Annex B(Clause 4.2)

Notations

$A =$ Surface area of a structure or part of a structure

$A_{\mathrm{e}} =$ Effective frontal area

$A_{z} =$ Effective frontal area of the building at height $z$

b = Breadth of a structure or structural member normal to the wind stream in the horizontal plane

$C_\mathrm{fs} =$ Cross-wind force spectrum coefficient

$C_{f,z} = \text{Drag force coefficient of the building corresponding to the area } A_z$

$C =$ Coefficient, which depends on $q_{\mathrm{s}}$, used in the evaluation of $k_{3}$ factor

$d =$ Depth of a structure or structural member parallel to wind stream in the horizontal plane

$D =$ Diameter of cylinder or sphere

$E =$ Wind energy factor

$F_{z} = \text{Along wind load on the building/structure at any height } z$

$F =$ Force normal to the surface

$f_{a}$ = First mode natural frequency of the building/structure in along wind direction, in Hz

$f_{c}$ = First mode natural frequency of the building/structure in across wind direction, in Hz

$f_{s} =$ Vortex shedding frequency

$F_{\mathrm{n}} =$ Normal force

$F_{\mathrm{t}} =$ Transverse force

$F^{\prime} =$ Frictional force

$G =$ Gust factor

$g_{\mathrm{R}} =$ Peak factor for resonant response

$g_{\mathrm{v}} =$ Peak factor for upwind velocity fluctuations

$h =$ Height of structure above mean ground level

$h_{x}$ = Height of development of a velocity profile at a distance x down wind from a change in terrain category

$\overline{\nu}_{\mathrm{d}} =$ Design hourly mean wind speed

$\overline{\nu}_{\mathrm{z,d}} =$ Design hourly mean wind speed at height $z$

$\overline{V}_{z,\mathrm{H}} =$ Hourly mean wind speed at height $z$

$w =$ Lesser horizontal dimension of a building, or a structural member

$w^{\prime} =$ Bay width in multi-bay building

$\hat{\dot{x}}$ = Peak acceleration at the top of the building/structure in along wind direction, in m/s $^{2}$ ;

x = Distance down wind from a change in terrain category

X = Distance from the summit or crest of topography feature relative to the effective length, $L_{e}$

$\hat{y} =$ Peak acceleration at the top of the building/ structure in across wind direction

z = Height or distance above the ground

$z_{0,\mathrm{i}} =$ Aerodynamic roughness height for $i^{\mathrm{th}}$ terrain

$Z =$ Effective height of the topography feature

$\alpha =$ Inclination of the roof to the horizontal

$\beta =$ Damping coefficient of the building/structure

$\eta =$ Shielding factor

$\phi =$ Factor to account for the second order turbulence intensity

$\Phi =$ Solidity ratio

$\Phi_{\mathrm{e}} =$ Effective solidity ratio

$\varepsilon =$ Average height of the surface roughness

$\theta_{\mathrm{s}} =$ Upwind slope of the topography feature in the wind direction

$\theta =$ Wind angle from a given axis

ANNEX C

(Clause 4.4.2)

BASIC WIND SPEED AT 10 m HEIGHT FOR SOME IMPORTANT CITIES/TOWNS

PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS