calcule of wood beams for free-standing floors

Question

First of all i hope your English is good enough to understand my question because my french is oral. So i am trying to calculate what size wood beams i need for a floor. it would be for a light load (150kg/m2) with a chipboard covering. When i asked the people that sell wood i get different answers. This is the plan i made:
[img=http://img118.imageshack.us/img118/365/mezaframejv5.th.jpg]

It would be really cool if somebody could give me the information i need to calculate all of this.

vms09 charpentier · Answer

hello you will need 100mm*260mm for the beams that are 5m long. You will put them with 50cm between each axis for the two others, you will need 120mm*310mm Regards Rémy

NeilP · Answer

thank you remy its really cool to have an objective point of view. When the opinions come from the people that sell its hard to be sure. p.s. how do you work out the forces, what are the formulas?

vms09 charpentier · Answer

thats not so simple, i have a specific software for some carpentry calculations. with it, calculating a floor is done in less than 1 minute.... there are a lot of parameters for wood calculations, that's why there are no ready to use formulas. And be carefull with the people that gives formulas on the net. above all, some very experimented old people can just give you the right dimensions because it's an habit and they are generally not bad Rémy

NeilP · Answer

you can answer in french if it is easyer.

NeilP · Answer

experimented old people don't always give the right dimensions. the dimensions were worked out by an old man.

vms09 charpentier · Answer

i don't have often the chance of speaking english, less often to write it... it's a pleasure for me Rémy

NeilP · Answer

the pleasure is mine. a simple answer to a complicated question that's cool !!!! can i just stack up the beams as in my drawing using metal plates and screws or is there a better way to fix all that together?

vms09 charpentier · Answer

the best way for you is to use "sabots" ( don't know the word in english ) from simpson strong tie company. Thats a piece of metal folded that you can screw on a piece of wood and inside you can put another one but crossed.... Rémy

NeilP · Answer

Are the sabot expensive?and is this about right?

NeilP · Answer

Is there any way i could do the same thing with less wood. it's not my money that i am spending but an "assosiation". could i put more feet (vertical beams) or more 7m beams etc? do you have any good ideas?

vms09 charpentier · Answer

yes sabots are a bit expensive. but it allows to put the 5m beams inside the 7m ones which is better for the floor : can't explain to you in english but beeive me it's better i don't think you will manage to save money but putting more 2.2m piece of wood or other solution...  Rémy

NeilP · Answer

when i look at the prices if the wood i need the most expensive were the 11 (or now 15) 5m beams and not the chunkier ones. They are sold by the cubic m.this is what i meen:

NeilP · Answer

if you have a few minutes could you run this version though your computer program to see if it comes out out with less m cubed.

the 5m span is with larger beams and the smaller beams are now 3,5m
i know your busy but i am curious. please.

NeilP · Answer

I know it is late but i can not sleep. i showed the plans to the rest of the "association" with the new size beams, it works out at about 3m³of wood. at 300 euros the m² it would cost about 900 euros. the problem is we have 1000 euros for everything. so i need to find a cheaper way of doing it.

my latest idea is to put central vertical beams hoping that it would lighten the load on the rest so i an use smaller sections and save a bit of money. a frame with no floor looks good but is not very practical. I have done some drawings to show you what i mean.

please please please run this though your computer program to see if it would be cheaper in the end.

vms09 charpentier · Answer

hello sorry if you had a bad night the 7m beams should be 100*180 the 9 "poteaux" can be 150*150 to save money the median beam 5m long should be 140*230 the two other beams 5m long should be 80*230 Estimated the cube meter of this new solution, i'm not sure it's better Rémy

vms09 charpentier · Answer

it's 2.17 cube m so you"r rigth it's cheaper Rémy

NeilP · Answer

Thats super cool. i will try to get a real price with the new sizes. the wood is the same cost up to 6.99m (about 300 euros/m³) after that it more expensive. so now with the "sabots" the 7m long beams are realy 3.5m?
thanks remy for your help.

omega · Answer

Bonjour!le sujet m'intéresse puisque je prévois une structure de même type chez moi; Pleins de questions bien sûr, et notamment: le plancher de NeilP va reposer sur 9 poteaux; comment ces poteaux sont liés au sol? En général on les voit reposant sur des plots bétons; Comment dimensionner ces plots? Faut-il absolument une ancre métallique scellée dans le béton? Et une autre question: faut-il prévoir des contreventements entre les poteaux et les poutres?Merci pour tout élément de réponse, Matthieu

NeilP · Answer

helloi can not drill holes in the floor. i was hoping that with over 2 m3 of wood the weight would be enough. the whole structure will be fixed to the metal structure of the warehouse on 2 sides and one side against a light wall. when we have more money we want to close the last wall with cp10 and light frame. a bit like this:i hope this gives you ideas. if it does share them

omega · Answer

Merci Neil, je comprends avec ce dessin qu'il n'y a pas forcément besoin de contreventement...
Par contre, pour les poteaux, je ne me rends pas compte: le poteau central est amené à transmettre au sol une charge de plus d'une tonne sur une section de 150*150; c'est le point qui me pose vraiment question pour mon projet...une dalle classique suffit-elle, sinon, quelle dimension de plot prévoir...

Matthieu

NeilP · Answer

it is a good question. i had never asked my self because the warehouse that we have had 20 ton trucks inside before and the concrete never cracked but if someone has an answer it is very interesting.

omega · Answer

Thanks Neil, I understand that in your case there is nothing special to do for the bases of the vertical beams!!I continue my search ...Matthieu

vms09 charpentier · Answer

yes Neil, the 7m beams are in fact 3.5m with the sabots. Rémy

NeilP · Answer

in fact i am happy the hole project (beams, sabot and floor osb) for about 1100. the rest is not structural and can be recuperated. thanks for all your help.

calcule of wood beams for free-standing floors

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