Structural Factor, c_sc_d: Section 6

The factor c_s is called size factor and c_d is dynamic factor. They can be calculated separately or calculated together, c_sc_d. Both cases are implemented in the program.

c_sc_d is calculated together as follows:

c_{s} c_{d} = \frac{1 + 2 k_{p} I_{v} (z_{s}) \sqrt{B^{2} + R^{2}}}{1 + 7 I_{v} (z_{s})}

(6.1)

where

z_s	=	reference height (Figure 6.1). It is taken as z_s=0.6 h
k_p	=	peak factor (ratio of maximum value of fluctuating part of response to its standard variation) (Annex B)
I_v	=	turbulence intensity (Section 4.4)
B²	=	background response factor (Annex B)
R²	=	resonance response factor (Annex B)

Or, they can be calculated separately:

c_{s} = \frac{1 + 7 I_{v} (z_{s}) \sqrt{B^{2}}}{1 + 7 I_{v} (z_{s})}

(6.2)

c_{d} = \frac{1 + 2 k_{p} I_{v} (z_{s}) \sqrt{B^{2} + R^{2}}}{1 + 7 I_{v} (z_{s}) \sqrt{B^{2}}}

(6.3)

Annex B is implemented to calculate the terms k_p, B², and R². Annex C provides an alternative way to calculate these terms, but it is not implemented. Note that the building dimensions ("b" and "d" from Figure 6.1) are needed for the calculation of B² and R². Two options are provided (see Building Width section in the load case dialog): you are allowed to enter "b" and "d" values directly or maximum exposure dimensions are used to obtain values of "b" and "d".

In addition, the user-defined structural damping value is used for total logarithmic decrement of damping, δ, which is need for calculation of R².

You are also allowed to enter c_s and c_d values directly (instead of calculating them according to Eqns. (6.1), (6.2) or (6.3)).

Structural Factor, cscd: Section 6

Structural Factor, c_sc_d: Section 6