# Which method is better for calculating shear force and bending moment of ship by usi

Discussion in 'Boat Design' started by xichyu, May 18, 2016.

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### xichyuJunior Member

1.The bearing shear force and bending moment of ship in longitudinal
direction can be got by using integration. Due to the existence of
accumulative error, it is difficult to guarantee that bearing buoyancy and
gravity of barge can be balanced completely. That is to say, shear force
and bending moment at fore-aft endpoint of barge is not normally zero.
Therefore, its shear force and bending moment curve should be treated with
non-seal correction, which makes the shear and bending moment whose
endpoint is not zero be assigned to curve according to linear proportional
relationship.

2.The shear forces and bending moment can be obtained from fore and aft by using integration. Then, there exist two different shear forces and
bending moment values in barge, and their average value can be the result
of shear force and bending moment at this place，

Last edited: May 20, 2016
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Just open any text book and the procedure is shown clearly how to do by simple hand calculations:

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### AlekseyJunior Member

I have surfed a lot of time in internet to find step by step way of calculation Bending Moment and Shear Forces on container vessel and can not find nothing.

4. Joined: Oct 2008
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There is your first mistake. Using the internet..it is not a source of everything!!
Check out any quality naval architecture reference book...it is all explained...read it...simple!

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### AlekseyJunior Member

How to say simple....))) A have presently a lot of naval arch. books. In this books described how to calc BM and SF for usual beam. I need example for container ship.

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### gonzoSenior Member

What difference do you find between a container ship and other types?

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Then clearly you do not have Basic Ship Theory by Rawson and Tupper.
Chapter 6, example 1...explains all very simply....

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### AlekseyJunior Member

I want to understand one thing: in stability booklet there are max BM and SF for 11 frames. And how to find weight of cargo, ballast, etc exactly for this frame? Or I need to take weights between frames?

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### AlekseyJunior Member

Thanks! Will try to find now

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### gonzoSenior Member

Page 634 has dimensional ratios for different types of ships

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### AlekseyJunior Member

This topic as I understand not for me (( I have make Load Distribution, BM and SF diagram but totally different with Cargo Program Calculation
Here is mine Load Distribution on the vessel

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### gonzoSenior Member

You also need to calculate the buoyancy at the same points you are applying the load (weights). Are you also considering the effect of waves or is this a vessel in flat water?

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### TANSLSenior Member

That is not totally correct. Buoyancy must be calculated along the entire length of the boat. It also happens that not all charges are punctual, many of them are distributed along a certain area of the ship.
But Gonzo, the most important, once calculated all that, how are the BM and SF calculated at each point?

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### gonzoSenior Member

If he calculated buoyancy at different points that where he calculated the weight, it introduces an unnecessary complication. The calculations are all explained on Chapter 6 (see post #7)

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### TANSLSenior Member

So, if I have understood well, buoyancy in the areas between the various points is not taken into account?

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