Design of floor joists in a domestic building

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The discussion focuses on designing floor joists for a domestic building with a 3.0m span between walls, using specific materials and dimensions. Key parameters include 50mm wide joists at 450mm centers, with a permissible stress of 5.3N/mm² and an elastic modulus of 8000N/mm², while deflection must not exceed 0.3% of the span. Participants emphasize the importance of local building codes and recommend consulting a licensed engineer for accurate calculations. The original poster clarifies that this is a college assignment, prompting further inquiries about material densities and live load requirements. Accurate design requires detailed calculations and adherence to local regulations.
john paul jr
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Could i have some help with the following:

Design, floor joists in a domestic building to span between walls 3.0m apart.

the construction of the floor is
18mm timber boards
joists
15mm overall plasterboard + skim coat

The joists are 50mm wide and at 450mm centres
The permissible stress in the timber is 5.3N/mm(squared) and the elstic modulus of the timber is 8000N/mm(squared)
the deflection must be limited at 0.3% of the span.
 
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john paul jr said:
Could i have some help with the following:

Design, floor joists in a domestic building to span between walls 3.0m apart.

the construction of the floor is
18mm timber boards
joists
15mm overall plasterboard + skim coat

The joists are 50mm wide and at 450mm centres
The permissible stress in the timber is 5.3N/mm(squared) and the elstic modulus of the timber is 8000N/mm(squared)
the deflection must be limited at 0.3% of the span.

What is your background? What city is this in? What are the local codes regarding this kind of construction? You need a licensed engineer to make those calculations for you -- one who is familiar with your municipality's building codes and inspectors.
 
Is this homework? If not, there's not much of a chance for getting an accurate result without knowing local building codes.
 
Even if we had a PE structural engineer as a member or on staff, we wouldn't condone giving such advice since we can't be sure this isn't a code violation (a homeowner trying to do his own structural engineering).
 
Thanks for getting back to me this is actually a college assignment that I've been stuck on for quite a while that i needed help on for designing the floor joists.
 
Ok so is a college assignment. Start off by showing your work, so we can know with what you are having problems.
 
john paul jr: Do you have the density of the timber boards, and of the joist material? Do you have the density of plasterboard? Do you have the floor applied live load per unit area?
 

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