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The actual stiffness of the connections is compared with the required stiffness, based on the approximate joint stiffness used in the analysis model. See also Ref.[15] Part 6.1.2, Ref.[18] and Ref.[19].
A lower boundary and an upper boundary define the required stiffness :
|
Frame |
Lower boundary Sj,low |
Upper boundary Sj,upper |
|
|---|---|---|---|
|
Braced |
|
|
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|
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Unbraced |
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with
|
Ib |
|
|
Lb |
|
|
Ic |
the second moment of area of the column |
|
Lc |
|
|
E |
the Young modulus |
|
Sj,app |
the approximate joint stiffness |
|
Sj,ini |
the actual initial joint stiffness |
|
Sj,low |
the lower boundary stiffness |
|
Sj,upper |
the upper boundary stiffness |
|
Sj |
the actual joint stiffness |
When a linear spring is used in the analysis model, we check the following :
When Sj,ini >= Sj,low and Sj,ini<=Sj,upper, the actual joint stiffness is conform with the applied Sj,app in the analysis model.
The value of Sj,app is taken as the linear spring value introduced for <fiy> (in the hinge dialog), multiplied by the stiffness modification coefficient η.
|
Type of connection |
h |
|---|---|
|
bolted beam-to-column |
2 |
|
welded beam-to-column |
2 |
|
bolted plate-to-plate |
3 |
When a non-linear function is used during the analysis model, we check the following :
When Sj >= Sj,low and Sj<=Sj,upper, the actual joint stiffness is conform with the applied Sj,app in the analysis model.
The value of Sj,app is taken as the analysis stiffness defined by the non-linear function.
For column base and weak axis connections, the stiffness checks in not performed.
