p-delta effect

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shjelvan
Posts: 7
Joined: Sun Feb 08, 2015 8:41 am
Location: university of tehran

p-delta effect

Post by shjelvan »

hello
i have a few questions about p-delta effects and i would be tankful for your answers and helps.
1) is there any other way except lineanig column for modeling p-delta effect?
2)can leaning column (p-delta effect) affect frame periods?in leaning column no mass assign to it nodes and it columns and beams are also pinned and they are not affect total stiffness matrix so it seems that it not affect periods.
3)does leaning column change displacements in dynamic analysis? i can see the effect of leaning column clearly in my pushover curve on values of base shear but i had problem in dynamics analysis where leaning column seems not working correctly. it seems that p-delta effect should increase node displacements and inter-story drift but this is not happening when i use leaning column in my model and even the values of inter-story drift decrease.
note that my model in pushover and dynamic analysis are exactly the same and my model is a steel moment frame.and i also use pdelta geotransfer for my columns .
fmk
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Re: p-delta effect

Post by fmk »

you only need a leaning column if you want t o include effects of the rest of the building. otherwise if you just want pdelta effect for frame you have give the columns in the frame a pdelta transformation

not initially. if they lean they will as it effects the K matrix.

the change will depend on the model. remember it is not a pushover, so higher mode effects reduce the effect of PDelta and can actually work in your favor (think about the way it can help against the inertia forces based on shape of deformed shape in dynamic analysis with higher modes effecting)
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