unsupported span

[Hisham]

Hi all

I have a simle question

in longitudinal systems what is meant by unsupported span for the deck center girder CG ?
is it the spacing between (transverse Web Frames) or the distance between the two BKHD (Bulkheads) that are carrying the CG ?

i am using GL

is it the same in BV?

hope to find the answer here?

thanks all

[MikeJohns]

Distance between supporting columns (and bulkheads).

[Petros]

That is correct, but actually it depends on the applied load direction. On a simple deck beam span for example, that has deck or cargo loads, then it would be the horizontal distance between the supporting columns or bulkheads or what ever holds the beams up for the vertical loads applied to the beam. The "clear span distance".

If you are talking about the hull forces trying to push the two gunwales together (or apart), than it would be the distance between the deck beams that run transversely from one gunwale to the other.

The word itself "unsupported span" usually means the distance between the member's support that is perpendicular to the applied load direction for members in bending. For columns with axle loads at risk of buckling, then it would refer to the distance between lateral supports. For example a 10 foot long column loaded vertically with a center brace and laterally supported at each end, would have an unsupported length of 5 feet.

[MikeJohns]

If it's a simple section modulus calc with chsl^2 type formula the unsupported span (l) is that of the load carrying member under consideration. In this case the distance between the bulkheads minus any allowance for brackets.

What scantling rule are you designing to Hisham?

[Arvy]

Thanks for all the replies, it made a lot clear to me. Even tho I didn't ask the question in the first place.

[Hisham]

thanks to you all

this is realy a great forum

basicly i am using BV and revising my results with ABS as it is too easy to understand and Clear than BV

but i think the concept is the same in all rules, as it is logic too

thanks again

[Felix-Arees]

Petros explanation is very well and very easy to understand Hisham., nice answer Petros

[Bijit Sarkar]

While what Petros has said is clear and coincise, it will help you to check the rules . If you have bracketed end connections, the clear span reduces, exact measure of which depends on the bracket sizes and are given in the rules.