P-Delta Analysis
P-Delta Analysis
(OP)
Greeting everyone.
This is the first time I use this forum.
May i ask how to do P-Delta analysis?
Thanks for your action.
This is the first time I use this forum.
May i ask how to do P-Delta analysis?
Thanks for your action.






RE: P-Delta Analysis
RE: P-Delta Analysis
Otherwise I believe you are stuck using the B1,B2 factors to get around this problem.
RE: P-Delta Analysis
it is because i am required to do both software and manual analysis.
May I show you a picture here?
its a cantilever circular steel column, fixed - free.
I show you the picture to give you a better understanding.
thanks
RE: P-Delta Analysis
1. Calculate your lateral deflection due to your side load.
2. Add a P delta moment to the model using your lateral deflection "+ a little" per engineering judgement. Also need to consider foundation overturning.
3. Recalculate deflections with both the P delta and lateral moments applied and check to see if you are close to your "+ a little" estimate.
4. Redo again if you want a closer number.
RE: P-Delta Analysis
I have never done this problem before. Could you recommend me that something I can refer? Or an example?
To be honest, I do not know how to start it.
RE: P-Delta Analysis
RE: P-Delta Analysis
RE: P-Delta Analysis
Theta = axial force * Delta / (Shear * story height)
Where Delta is the initial deflection due to the applied shear.
This is a ratio of P-Delta shears to the original story shears. The additional deflections due to the 2nd, 3rd, 4th iterations of deflection would then be:
Theta*Delta + Theta^2 * Detla + Theta^3 * Delta +....
The infinite sum of this series becomes:
Delta total = Delta /(1-theta)
In the end, this is really just an approximate hand calculation. Doing the P-Delta analysis with a computer program will normally provide a better result. Even so, it is never a bad idea to give computer results a sanity check using these types of approximate hand calculations.
RE: P-Delta Analysis