When is P-Delta Calculation required?
When is P-Delta Calculation required?
(OP)
Can someone tell clearly when is a P-Delta Analysis required to be done? I seldom perform such calculations in steel buildings.
Thanks,
Thanks,
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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When is P-Delta Calculation required?
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RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
Best to carry out a second order analysis, particular when members are required to resist large compression forces combined with bending such as sway frames, a second order analysis can add significantly to the drift.
RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
You are correct that X-bracing means little lateral deflection of the X-brace. But with large warehouse structures, the metal deck diaphragm can have significant lateral second-order deflections between the brace lines and this can significantly add to the lateral loading of the structure and should be checked.
RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
Cheers!
RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
RE: When is P-Delta Calculation required?
Mtot = F H + P (FH^3/3EI) = F H [1 + (P H^2/3EI)] =>
Approximately: Mtot = M1 (1 + P/Pcrit)
Because for a cantilever beam:
Pcrit = (pi^2 EI) / (2H)^3 = (9 EI) / (4 H^2)
So you can notice that if P is quite similar to Pcrit (Euler's load) the Mtot is twice bigger than M1.
In other words, with a little P you have little 2nd order effects, maybe negligible. But watch out if your element has a big axial load. In that case you MUST verify second order effects.
RE: When is P-Delta Calculation required?