# Thread: Hospital Pendants Structural Calculation

1. ## Hospital Pendants Structural Calculation

Hi,

I m asked to calculate the allowable load for a designed hospital pendant which needs to be mounted on the ceiling.
The company has given me a similar sample to take reference but I have a lot of steps which I don't understand, so sorry there may be a lot of questions I need to ask for...

First, at page 3, Spreading area = (560+2x90)x(311+2x90) = 740x491mm^2
I don't know where are those numbers come from?

And at page 4 about the Restoring moment about edge, I also don't understand the whole step, where 9.8 kN comes from and FS = 14>1.5. Does FS mean Factor of Safety?

And last at page 6, starting from Check Restoring Moment: 3 nos. of M10 HSL
It will be grateful if anyone could explain whole calculation steps.

Thank you for helping
Door Detail WD04.2.pdf

2. Having looked through this, I have to say, the engineer hasn't done a very good job of outlining his methods. In the UK it would be typical to say "blah blah requires a blah thick plate. The plate is to be analysed using the blah method." This makes it easier to check too.

Spreading area - The only thing that comes to mind is some sort of effective area method. Without seeing the equations, its hard to say.

Restoring moment - I'm guessing that the 9.8 kN is the factored SWL of a singular bolt. The whole step is the engineer checking the turning moment from the centre of the pendulum arm Vs. the resistance moment of the bolts.

Check Restoring Moment - I don't know why 3 bolts are being checked when 4 have already been specified. I think he may of had a brain fart and wrote 3 No HSL M10 instead of HSL-3-M10 which is the type Hilti bolt he wants to use.

Without being able to go through it with the designing engineer, all of the above could be a bag of BS so take it with a fat spoonful of salt.

P.S.

Hope it helped.

EDIT
I think you're correct that FS = Factor of Safety, personally, I always write FoS so it can't be confused or taken out of context with any-other loading.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•