Permissible Shear forces and bending moments harbour/ still water

Discussion in 'Class Societies' started by JoshTruman, Mar 17, 2019.

1. Joined: Dec 2018
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Location: Lithuania

JoshTrumanJunior Member

Good day friends,
I'd like to ask you about - how to calculate permissible shear forces and bending moments in harbour condition and still water .
I just want to calculate it manualy for existing model of the ship.
It is easy to calculate shear forces and bending moments acting through the ships lenght but I do not know how to calculate/ derive permissible value for exact position i/e: x=50 [m] to plot curve of permissible shear/ bending curves for harbour and still water.
I am kindly waiting for any advice/ suggestion or working example.
Best Regards

2. Joined: Oct 2008
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Location: Japan

Josh

Just follow the procedure shown and outlined in any good naval architecture text book.
Work out the weight per unit length and lay over the buoyancy curve when in a static condition:

and then, obtain the positive and negative contributions along the length:

and then, apply a wave (buoyancy curve) onto the static vessel:

That's it.

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3. Joined: Sep 2011
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TANSLSenior Member

The shear force at point X is equal to the weight at that point minus the buoyancy in it. The bending moment is the resultant of the moments of the forces located to the right of said point with respect to that same point. As "simple" as that.

4. Joined: Dec 2018
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Location: Lithuania

JoshTrumanJunior Member

Many thanks for your reply- calculation of SF and BM is simple.
I mentioned maximum safe range of shear force and bending moment in function of length of the ship. Permissible harbour/ Seagoing( sometimes called stillwater) limits.

Best regards

5. Joined: Sep 2011
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TANSLSenior Member

Consult what Classification Societies or any other regulatory body says about it.

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