Rotational Restraint CD,C

Rotational restraint C_D,C due to the bending stiffness

C_{D, C} = C_{D, C} / e

C_{D, C} = \frac{k \cdot E \cdot I}{s}

E	Modulus of elasticity
k	Coefficient for position (inner span, outer span)
I	Moment of inertia I_y
s	Beam spacing
e	Distance of the purlins

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