This is a whole science. The choice of rule depends on the type of wood, number of knots, residential/office, how much deflection one can accept, etc...
Fortunately, there is an overview dimensioning available at.
http://www.traguiden.se/
Log in and check under planning.
You can also read and learn a lot about wood in general.
Good Luck.
/CC
Fortunately, there is an overview dimensioning available at.
http://www.traguiden.se/
Log in and check under planning.
You can also read and learn a lot about wood in general.
Good Luck.
/CC
For me too, but you can stick your neck out 
If you have two fixed points with cc600 between them, and place a regel/råplan 145x45 on its edge over that, I believe you can load 1 ton on the regel without it breaking.
Maybe someone wants to increase a bit
If you have two fixed points with cc600 between them, and place a regel/råplan 145x45 on its edge over that, I believe you can load 1 ton on the regel without it breaking.
Maybe someone wants to increase a bit
Mention the span you need, and there is probably someone here who will quickly answer which timber dimension you require!
/Ingenjören
/Ingenjören
If we say that we have a uniformly distributed load over the beam, the formula for deflection looks like this:
5 * Q * L³
f = ___________
384 * E * I
f = deflection (m)
Q = The distributed load ( N/m )
L = Length of the beam ( mm )
E = Modulus of elasticity for the material ( N/mm² ) = 7.0 * 10³ for K12 structural timber
I = Moment of inertia (mm^4) = ( Width * Height ³ ) / 12
Something like that, clear as crystal, right?
(Formula and values are taken from my teflon-coated head, so don't bet the house on their accuracy)
5 * Q * L³
f = ___________
384 * E * I
f = deflection (m)
Q = The distributed load ( N/m )
L = Length of the beam ( mm )
E = Modulus of elasticity for the material ( N/mm² ) = 7.0 * 10³ for K12 structural timber
I = Moment of inertia (mm^4) = ( Width * Height ³ ) / 12
Something like that, clear as crystal, right?
(Formula and values are taken from my teflon-coated head, so don't bet the house on their accuracy
)The formula for deflection of distributed load shall be:
4
5 x q x L
f = ------------
384 x E x I
E = 5.2 N/mm[sup]2[/sup] for K12, load type A, climate class 0
The deflection should not be greater than L/300 for total load (L/500 for variable load only)
In addition, it is common to ensure that the deflection of a point load of 100kg (P = 1kN) is less than 1.5mm to avoid the floor feeling wobbly.
3
P x L
f = ------------
48 x E x I
These formulas work for larger spans where deflection is generally decisive.
However, they do not address the strength which must be checked separately (Moment, shear capacity, supports, fixings etc. depending on construction).
The values of E also vary with the timber's strength class, climate class, and load type. E=5.2 N/mm[sup]2[/sup] applies for load type A, K12 and climate class 0 or 1, which means standard construction timber class K12, indoor environment, and residential load (fixed load portion).
/Ingenjören
4
5 x q x L
f = ------------
384 x E x I
E = 5.2 N/mm[sup]2[/sup] for K12, load type A, climate class 0
The deflection should not be greater than L/300 for total load (L/500 for variable load only)
In addition, it is common to ensure that the deflection of a point load of 100kg (P = 1kN) is less than 1.5mm to avoid the floor feeling wobbly.
3
P x L
f = ------------
48 x E x I
These formulas work for larger spans where deflection is generally decisive.
However, they do not address the strength which must be checked separately (Moment, shear capacity, supports, fixings etc. depending on construction).
The values of E also vary with the timber's strength class, climate class, and load type. E=5.2 N/mm[sup]2[/sup] applies for load type A, K12 and climate class 0 or 1, which means standard construction timber class K12, indoor environment, and residential load (fixed load portion).
/Ingenjören
The deflection is calculated separately for each load type and the different deflections are added together. For a floor structure in a residential building, there are typically 3 load types P=self-weight, A=useful fixed load, B=useful free load. The modulus of elasticity varies with the load type.
In deflection calculations, one can account for interaction with the flooring particleboard if it is screw- or nail-glued to the floor joists. In the calculation of deflection, this interaction is usually not considered. Lateral load distribution can also be considered in deflection calculations.
Example
Floor joist 45*220, K24, center distance 60cm, residential house indoors, normal self-weight, supported on two ends. 22mm flooring particleboard. No lateral torsional buckling. No holes in the beam. Shear deformations are not considered.
Screwed flooring particleboard. No lateral load distribution. Max span 3.1m. Deflection decisive for the span.
Screwed flooring particleboard. Lateral load distribution (particleboard). Max span 3.3m. Deflection decisive for the span.
Screw-glued flooring particleboard. No lateral load distribution. Max span 3.8m. Deflection decisive for the span.
Screw-glued flooring particleboard. Lateral load distribution (particleboard). Max span 3.9m. Deflection decisive for the span (permanent damage, max deflection L/300 or max 20mm).
In deflection calculations, one can account for interaction with the flooring particleboard if it is screw- or nail-glued to the floor joists. In the calculation of deflection, this interaction is usually not considered. Lateral load distribution can also be considered in deflection calculations.
Example
Floor joist 45*220, K24, center distance 60cm, residential house indoors, normal self-weight, supported on two ends. 22mm flooring particleboard. No lateral torsional buckling. No holes in the beam. Shear deformations are not considered.
Screwed flooring particleboard. No lateral load distribution. Max span 3.1m. Deflection decisive for the span.
Screwed flooring particleboard. Lateral load distribution (particleboard). Max span 3.3m. Deflection decisive for the span.
Screw-glued flooring particleboard. No lateral load distribution. Max span 3.8m. Deflection decisive for the span.
Screw-glued flooring particleboard. Lateral load distribution (particleboard). Max span 3.9m. Deflection decisive for the span (permanent damage, max deflection L/300 or max 20mm).