Posted by Per Corell on December 03, 2002 at 04:08:51:
In Reply to: Re: Floating Bridge ... reinventing the pontoon posted by Manuel Oliveros on December 02, 2002 at 10:11:52:
I will do my best, to justify the choices I made according to structure and design about this Bargebridge.
First issue I find very important, is the fact that it is the same shape frame that is used along the intire length of the Barge hull.
------ Now as this is a 2D-H framework, infact there are two different frame shapes ,as one side of the framework will need assembly slots pointing down and the other side, pointing up to provide a possible assembly, so unlike some other 3D-H frameworks ,where it is the idear that the shape of the frame ,don't care as this issue are only about how many feet you need to cut ,while you can cut whatever shape and it will fit into the rest of the frame structure , -------- then with two almost identical shaped frame types ,you can produce the Bargebridge , the length you want.
Now about the choice about 3D-H, I guess you know that this don't leave me with any choice but I se your point. Still the 3D-H were acturly develobed as an attractive alternative, for ships frames and I proberly need to point to why an intergrated framework is so attractive in this application ; as there are a number of resons.
First , in the process where you hands-on are to produce the actural hull ,you find yourself in a situation ,where you need to place a number of ribs to even be able to place the paneling, ---- this is a major problem if you work from the tradisional way how you build a ship ,this requier "lofting" , this mean that you must develob a plane drawing, so you can transfere scaled measures onto standard vertical frames that oposed 3D-H are not interconected to keep the shape while placing the paneling. You spend a lot of time preparing to be able to place panels and this is an expensive and complicated job. Emagine yourself placing a heavy panel onto swinging frames where you must be glad when each panel are just in near it's place on a framework being a hell to project ; now you can say that with tradisional ribwork, the ribs also are identical along the hull, but a 3D-H framework are first of all much more form stable and secondly when you decide for a more "boat-like" shape in the ends of the Bargebridge you realy will se the advanteages of 3D-H and the reson the technike was develobed.
The structure of a 3D-H in a ships hull are ideal, as it will allow the hull to twist without focusing the stress in the weakest places and this way you also control the structure and are able to produce a lightweight structure by the fact that the structure is shaped in the most effective way forming a honeycomb structure rather than a skin-frame-stringer structure.
This offer a number of positive side effects, please check the Cyber-Boat site, where you se hulls where this is a major safety issue ;
This vessel have the floors above water and if the room within the hull are filled with foam, and any water that "enter" the hull ,will run strait out into the sea again.
So please also se the Bargebridge as a "thick hulled" boat construction, where it is no problem, if there are water "inside" the boat as the boyancy come from the thick hull shell, formed as a paneled honeycomb cell structure.
As sketched with my proposal, there will be a huge volume inside the hull and as you point to, there are no doubt ,that there are a number of possible way's ,to refine a Bargebridge . As I point to ,I am not satisfied with the bottom shape and the fact the Bargebridge have no boat ends, as when it have these ,it is much easyer to form a shape , better fittet to restand sideverts waves making the use of moving water ballast a minimum by a better design.
Now hands-on ,I will say that the 3D-H in all respects, are a better choice for producing the all important framework, in a shape and condision to ease the building of any boat hull made from sheet materials. ----------- I se _no_ reson to project the Bargebridge first in 3D-H , and then re-project the structure into a troublesom tradisional way of constructing ; the 3D-H framework process work much more smooth and bring a more reliable and much simpler and stronger structure where addisional structures will smooth in , instead of being clumpsy adding. As just a detail, you can this way , at any time add a bridge deck or a low climat shell cover, but first of all ,the 3D-Honeycomb framework will simplyfi the producton .
Now I did agrea that this Barge bridge are at sketch level, but the graphics you seen also show a very important issue about 3D-H ; the fact that for each drawing I been publishing ,there acturly have been the true assembly. The fact that to be able to show a 3D-H project, the thing are acturly compleated as each part of the assembly exist in the 3D drawing, ----- that I can not show this bridge or any other 3D-H framework, unless I realy projectet each and every assembly piece ,as this is what you se in the renderings ,the complete assembly to produce the object.
This is also why I resist going back to the tradisional ribworks as in any respect, this is a step back.
Guess you se what I mean, as a 3D-H structure can be a simple one offering a single thick shell of honeycomb structure, but the structure can also be made double and other frameworks can be prepared to intergrate ; I know this sound complicated, but it is not and before you attempt to replace the 3D-H structure with the tradisional one, please ask yourself what is acturly the best ;))
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