Torsional Spring Stiffness for Serviceability Limit State

Torsional spring stiffness for the serviceability limit state

C_{φ, SLS} = K_{ser} \cdot I_{p}

C_φ,SLS	Torsional spring stiffness for the serviceability limit state
K_ser	Displacement modulus of a fastener
I_p	Polar moment of inertia without component of fastener surfaces

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