Preliminary prediction of stiffness
The preliminary prediction of detail stiffness may be beneficial for correct structural analysis of complete structure. Following expressions may be used. Initial stiffness of detail is calculated using expression
where z is the inner lever arm. It's a distance between the centre of compressive flange and bolts.
Inner lever arm
References
Wald F., Bauduffe N., Sokol Z.: Preliminary Prediction of the Column-Base Stiffness, in Steel Structures of the 2000´s, Istanbul 2000