# Buckling of profile

Discussion in 'Sailboats' started by pulsar, Sep 15, 2007.

1. Joined: Aug 2006
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### pulsarMechanical engineer

Hi,

How to calculate buckling of beam (length L, circular section), which is fixed on 6 degree of freedom at bottom part (movement and rotation) and catched at the end. I have axial force and out of center force at the endas it is shown on picture. I have found examples with only axial forces for that moments, but it don't help me.
I need some simple explanation. I mean with simple formula without integrals and differentials.

Pulsar

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### GuillermoIngeniero Naval

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### MikeJohnsSenior Member

Unfortunately there is no easy solution. Eccentrically loaded columns require some complex mathematics and manual solutions would start with the Secant formula. As Guillermo has suggested the answer for an easy solution for you lies in software. I would recommend that you use "Cadre" from Guillermo's second link above. It comes with excellent tutorials and supports cable elements as well. Cross check any calculated second moment of area with some one else's calculations to ensure you are in the ball park.

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### tspeerSenior Member

Try Roark's Formulas for Stress and Strain. My copy is at the office, so i can't look it up for you at the moment.

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### pulsarMechanical engineer

oh... it's more optimistic news.

Pulsar

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### PI DesignSenior Member

Yeah, Roark has a table for eccentrically loaded columns. There is no single easy formula as it depends, amongst other things, on the cross sectional shape of the column.

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### pulsarMechanical engineer

I beg your pardon, but who is Roark and how to get those formulas?

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Curious- why do you need this? Just happily computing away buckling equations for fun?

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### pulsarMechanical engineer

I'm during designig gangways for roro ships. Buckling calculation is for checking main beams which support passengers stairs.
The main beam must be small as it's possible.

That's why

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### GuillermoIngeniero Naval

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