calculating shock loading?

[gnomatron]

How do you calculate shock loadings? for example, what the attachment point would need to be rated at if someone of a known weight were to fall a known distance whilst harnessed to said point? What other data would you need to make the calculation?

[Seano]

How do you calculate shock loadings? for example, what the attachment point would need to be rated at if someone of a known weight were to fall a known distance whilst harnessed to said point?

 

You dont: if you're installing an anchor point for a fall-arrest system (in the EU) you make it comply with standard EN795. (BS EN 795 in the UK)

British standards are quite expensive to buy, but you can get a read of it for free via your local library (assuming you still have one).

 

As far as loadings go, the anchor point would need an ultimate strength in excess of 15kN to meet the standard.

[andy_s]

How do you calculate shock loadings? for example, what the attachment point would need to be rated at if someone of a known weight were to fall a known distance whilst harnessed to said point?

 

You dont:

Albert Pierrepoint used to make such calculations regularly ... of course it wasn't his objective to ensure the falling body survived! :o

[gnomatron]

hmm, ok. What if it's something like an aerial performance which involves a fall as part of a routine? That rather falls outside the BS' definitions.

 

Or, for that matter, what about harnessing onto trussing? If I understand correctly, 1kN is equivelant to something like 100kg of static load, so you'd need a truss with a point load rating over 1500kg to provide an anchor point that meets the BS.

[ImagineerTom]

You need to ask a specific question if you want a specific answer - vague "what ifs" with no details means no-one can give you an answer.

 

If the performance involves a "fall" then I'd expect it involves a skilled, experienced performer who'll be able to tell you precisely what loading/load capacity they need and how they'd like it.

 

 

[Seano]

hmm, ok. What if it's something like an aerial performance which involves a fall as part of a routine?

Then it comes down to a "competent person" to do the requisite calculations, risk assessments, blah blah blah.

 

If I understand correctly, 1kN is equivelant to something like 100kg of static load

Kind of ish, yes.

 

so you'd need a truss with a point load rating over 1500kg to provide an anchor point that meets the BS.

Depends what you mean by "load rating".

Usually when you talk about what the "load rating" of a rigging point is, you're talking about its SWL (Safe Working Load), not its minimum breaking load.

[oscarkane]

Knowing the Mass [weight] and Distance of travel you can calculate the Impact Velocity [ the force applied when you come to a sudden stop] = square root of 2 times the distance times force of gravity [9.8 meters per second squared].

This is why it is so important to use some type of energy absorbing device between you and your anchor point.

 

How do you calculate shock loadings? for example, what the attachment point would need to be rated at if someone of a known weight were to fall a known distance whilst harnessed to said point? What other data would you need to make the calculation?

 

 

 

[Smiffy]

How do you calculate shock loadings?

 

I don't.

 

I get a competent rigger, and if a required, a licensed structural engineer to do it for me. Takes a load off my mind, and my insurance costs ;)

[abbotsmike]

As said any element of falling onto a static anchor will likely break things. (anchors, bones, you get the idea) There will need to be some sort of dynamic element, so that the fall is slowed, rather than brick wall stopped dead. Although it seems clear that you will need to find out more info about this, what is the performance?