PDELTA ANALYSIS
PDELTA ANALYSIS
(OP)
Could any fellow structural designer share with me his/her experience on how to replace buckling length factor K by direct application of P-Delta analysis. Please consider a 3 dimensional steel frame model to analyze using for both vertical and lateral loads and utilizing a finite element analysis software.
Thanks in advance.
Thanks in advance.






RE: PDELTA ANALYSIS
RE: PDELTA ANALYSIS
Also I would like to have someone to show a point of view about this subject.
CV
carlosvalinhas@netcabo.pt
RE: PDELTA ANALYSIS
In summary, use PDelta or use moment magnification not both. See the response above.
RE: PDELTA ANALYSIS
eurocode 3 allows k=1 if second order analysis is made,but you have to take some fictitous lateral loading into account.also check ssrc guide on this subject.
RE: PDELTA ANALYSIS
'effective buckling length' to the physical length, or, in other words, is a factor for determination of axial buckling strength of the member. The p-delta analysis, on the other hand determines the additional stresses (primarily bending) induced on account of deformations in the presence of high axial stresses. If you are performing a design or verifying a member adequacy, you cannot ignore k-factor.
If you are verifying the member adequacy based on an analysis which includes p-delta
effect as well as other nonlinear effects (tangent/secant stiffness - stability functions, large deformation effects etc, you may use the interaction formula
(fa/Fa) + (fb/Fb) less than or equal to 1.0.
When you do a conventional linear analysis you would be using the interaction equations as per AISC
(fa/0.6Fy) + (fb/Fb) less than or equal to 1.0 and
(fa/Fa) + (Cm. fb / (1 -fa/Fe') / Fb) less than or equal to 1.0.
The commentary on these equations in AISC (I remember the 8th Ed) describes the basis. The moment magnifying factor (1-fa/Fe') was the easier way of incorporating the p-delta effect approximately.
Hope this helps.
M. Hariharan