load distributed on sheet and thickness assessment

[Shelby]

Hello!
for pure exercise I was evaluating the size of a sheet (framed with l=1 m) leaning with a distributed load. the purpose is to estimate the minimum thickness according to a certain load so that it does not infect.
as recommended in other forum threads I reported to the case of a simple beam supported and I was evaluating the tensions with parameters following the de saint venant.
I have doubts about the setting:
1) how do I assess the load distributed from a certain weight in n?
2) to calculate the moment of inertia and therefore the thickness which section should I consider?

the idea was to calculate the maximum time and maximum voltage and to compare it with the admissible values of the material (e.g. s235jr).

remain available in case I had not been very clear in describing the scheme.
Thank you!

 

[Mattymecc]

you should use the formulas of the "roark's stress and strain formulas", I don't think you can use the theory of Saint-venant beams for a slab. .

 

[meccanicamg]

the topic has been treated in several posts and all refer to the formulas of roark's. find the book online... .
The slab does not act like a beam.

 

[Shelby]

I had seen references to roarks in other threads... my intention was to make a maximum assessment here
thanks for the answers!

 

[Legs]

the beautiful of steel is that it has a great resistance and therefore suffice small thicknesses to support high loads.
but, the real problem is deformation. for variable loads only you should not exceed 1/300 of the light otherwise it means that when you walk above it starts to dance.
the ratio can also be lowered to 1/250 if it also contains the weight of the permanent.
on the covers it is not strange to descend even to 1/200.

We indicate with qk the characteristic value of the load and with qd its ultimate value (I pass the weight of my own. maybe for exercise you consider it):
stress value med = qd*l^2/20,9 (approximately)
with qd = 1.5*qk
resistant value mrd = fsd*t^2/6 (unified width strip)
con fsd = 235/1,05 = 223,8 n/mm2
the arrow is calculated with: f = 0.00406*qk*l^4/b
with b=e*t^3/(12*(1-n^2) with n=0,3 and e=206000 n/mm2
all formulas you find on any manual.

for example for a load of 2 kn/m2 you get a thickness of about 2mm.
but to respect the arrow of about l/200 it is necessary to increase the thickness to 4,4mm.
Normally it is considered for a mandorlata plate (or similar) that can be considered the maximum thickness (and not the average) of the plate in the calculation. therefore with a base thickness plate of 2mm and almond of 3mm here the accounts return (it actually works because in previous calculations I limited the resistance to achieving the plastic threshold. if we consider complete plasticization we have additional resistance to draw from).

 

[Molina]

Good morning.
from the calculations it turns out a bending 115mm leaning a load of 350kg on a plate of 1mq mandorlata in fe s275 sp. 3+2... incorrect value. Could you give me some suggestions?

 

[volaff]

Good morning.
from the calculations it turns out a bending 115mm leaning a load of 350kg on a plate of 1mq mandorlata in fe s275 sp. 3+2... incorrect value. Could you give me some suggestions?

roark's formulas for stress and strain - capitolo 11

 

[PIETRO2002]

roark's formulas for stress and strain - capitolo 11

puoi publicare le formulas? Grazie

 

[volaff]

Bye.
Annex to Chapter 11.

 

[PIETRO2002]

Bye.
Annex to Chapter 11.

thanks for sharing!

 

[Molina]

Bye.
Annex to Chapter 11.

Thank you very much!