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#1 Thrashed

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Posted 27 March 2016 - 08:13 PM

Hi guys

 

i am making a jacking beam for a ramp i have made and need to work out how much weight box section will take.

 

The bar will be 2m long and jacked at the centre point.  The max size box section i can use is 40x40.  Thickness can be anything up to 4mm.

 

I need it to be able to take at least 2 tonne so that i have a 100% safety margin.

 

Can anyone help with calculations.

 

Thanks

 

Steve



#2 peter2b2002

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Posted 27 March 2016 - 08:20 PM

Google it's been over 30 years since I did these calculations
peter2b

#3 Thrashed

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Posted 27 March 2016 - 08:24 PM

Google it's been over 30 years since I did these calculations
peter2b

 

Thanks, tried that, but made not sense and dont wont to risk my life of google.  



#4 2b cruising

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Posted 27 March 2016 - 08:35 PM

If it is welded both ends to a jacking plate, its strength is much greater.
Use the max gauge possible. Put a length at an angle on the kirb and ask a friendly bus driver to run over it. 😬
You should be able to jack it up somehow to find its strength. Nothing like a bit of practical instead of math.

Edited by 2b cruising, 27 March 2016 - 08:42 PM.

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#5 Shaft

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Posted 27 March 2016 - 08:40 PM

have a read here. It's complex to explain without an essay.

 

Be aware as you're using it for jacking as the 'bounce' effect creates a dynamic load rahter than a 'static' load.

 

Also, the 8:1 ratio for SWL if wanting insurance. i.e lifting 100kg swl the beam must test at 800kg.

 

http://www.engineers...calc_menu.shtml


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#6 Thrashed

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Posted 27 March 2016 - 08:54 PM

have a read here. It's complex to explain without an essay.

 

Be aware as you're using it for jacking as the 'bounce' effect creates a dynamic load rahter than a 'static' load.

 

Also, the 8:1 ratio for SWL if wanting insurance. i.e lifting 100kg swl the beam must test at 800kg.

 

http://www.engineers...calc_menu.shtml

Thanks, saw these calcs and this made no sense.  Never considered the bounce effect.   Got no issue with a 8:1 ratio for safety.

 

Is anyone able use these calcs to telling me the load bearing of a 2000x40x40x4mm mild steel box section.

 

Thanks



#7 Shaft

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Posted 27 March 2016 - 10:09 PM

It's unfortunately not as simple as A+B=C Steve.
There are numerous variables to take into account to glean your answer.
You say 2m long but the point of load won't be a singular point in the middle so you'll need to know how your proposed 2 tonne load will be spread over the length.
To learn the swl you need to firstly work out the deflection for a given load at a given point, but how far along the 2m? (Hence the need to know load spread?)

Sorry to be vague but that's why I posted the link above; more for explaining what I'm getting at rather than using it as a calculator.
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#8 Thrashed

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Posted 27 March 2016 - 10:15 PM

It's unfortunately not as simple as A+B=C Steve.
There are numerous variables to take into account to glean your answer.
You say 2m long but the point of load won't be a singular point in the middle so you'll need to know how your proposed 2 tonne load will be spread over the length.
To learn the swl you need to firstly work out the deflection for a given load at a given point, but how far along the 2m? (Hence the need to know load spread?)

Sorry to be vague but that's why I posted the link above; more for explaining what I'm getting at rather than using it as a calculator.

Thanks Shaft

 

Been doing some calcs and the deflection of a 2m bar is 0.01045 inches and the bending stress is 120.47 psi.

 

Going to work through the website you gave me.

 

Thanks for the help.



#9 Shaft

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Posted 27 March 2016 - 10:20 PM

No worries. Welcome to my world! Lol.
Have a read here also, it talks through the fundamentals of deflection and the ratio of compression to tension versus the neutral line of any given beam but more in Layman's terms than the 1st link.
I'm happy to help with any calcs if you need me but you'll learn more from good old fashioned reading.

https://en.m.wikiped...rg/wiki/Bending

Edited by Shaft, 27 March 2016 - 10:22 PM.

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#10 richyb66

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Posted 28 March 2016 - 08:49 AM

Steve, I'm off work next week but if you give me a sketch on Wednesday night I'll get one of our CAE guys at work to run it through their FEA software.


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#11 Thrashed

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Posted 28 March 2016 - 09:10 AM

Steve, I'm off work next week but if you give me a sketch on Wednesday night I'll get one of our CAE guys at work to run it through their FEA software.


Thanks Rich. Will bring with me. See ya Wednesday

#12 Ian & Carole

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Posted 28 March 2016 - 10:26 AM

It's threads like this one that  confirm what a great club this is.

 

We must all save our £15.00 / year membership every time we ask a question on  here.   :clapping:  :clapping:  :clapping:  :drinks:


 


#13 Tim Norman

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Posted 30 March 2016 - 09:23 PM

I have a 2T jacking beam from sgs engineering I can stick a tape  on it tomorrow if that helps?


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#14 Thrashed

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Posted 30 March 2016 - 11:01 PM

I have a 2T jacking beam from sgs engineering I can stick a tape  on it tomorrow if that helps?


Thanks, that would be very helpful. If you can measure the width and height of the box section they use plus what gauge metal the box section is made from that would be great.

Cheers

#15 Tim Norman

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Posted 31 March 2016 - 03:56 PM

Jacking beam

 

Centre section is 95 x 50mm 4mm thick


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