CR4® - The Engineer's Place for News and Discussion®

 Previous in Forum: Volume of an Object by Using Calculus Next in Forum: Activated Sludge Question
Member

Join Date: Jan 2016
Posts: 5

# Hospital Pendants Structural Calculation

01/13/2016 12:03 AM

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

https://www.dropbox.com/s/gy6sl2ms1wmqwco/Door%20Detail%20WD04.2.pdf?dl=0

Interested in this topic? By joining CR4 you can "subscribe" to
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 19269
#1

### Re: Hospital Pendants Structural Calculation

01/13/2016 1:50 AM
__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Member

Join Date: Jan 2016
Posts: 5
#4

### Re: Hospital Pendants Structural Calculation

01/13/2016 10:45 PM

I think the calculation sheet mainly just want to show the allowable load which the metal plate with anchor fixings can take. The spec of the hospital pendants is only a comparison table to confirm whether the pendant can be mounted on the ceiling safely, which I don't think the numbers there can explain my questions on this calculation, or do you have other thoughts?

Guru

Join Date: Oct 2008
Posts: 39901
#2

### Re: Hospital Pendants Structural Calculation

01/13/2016 8:52 AM

Ask Paul Kong Ming to explain it to you.

Score 1 for Off Topic
Member

Join Date: Jan 2016
Posts: 5
#5

### Re: Hospital Pendants Structural Calculation

01/13/2016 10:50 PM

Well, we are not from the same company. I have only been asked to do that both for practice purpose and if any future construction then I may be asked to demonstrate a calculation. Anyway, I have asked him and it might be best way because he knew what he was doing on those steps but it is not likely he will reply my email though...

Guru

Join Date: Mar 2010
Location: In the pool because it is too hot.
Posts: 3018
#3

### Re: Hospital Pendants Structural Calculation

01/13/2016 9:50 AM

I'm no drop (or other) boxer.

__________________
Plenty of room here
Member

Join Date: Jan 2016
Posts: 5
#6

### Re: Hospital Pendants Structural Calculation

01/13/2016 10:52 PM

Hi,

Send you another link, this forum can't upload things bigger than 500kb

Guru

Join Date: Sep 2009
Location: Louisville, OH
Posts: 1047
#7

### Re: Hospital Pendants Structural Calculation

01/13/2016 10:58 PM

When I was designing stuff, we sometimes puzzled over what the effective area was, knowing that it extended beyond the actual edge, but not how much. That's probably what the page 3 calcs are about, but I have no idea what algorithm they are using.

I don't think you want to attach this to any ceiling--drop, false, whatever. What sort of structure is above the ceiling? And, of course, the place they want it will probably be at some position between the structural material. Therefore, you will need to figure shear, moment, etc on some sort of spanning plate or beams.

Or am I all wet in my assumptions?

__________________
Lehman57
Member

Join Date: Jan 2016
Posts: 5
#8

### Re: Hospital Pendants Structural Calculation

01/13/2016 11:23 PM

ok, fair enough. So 560 and 311 are only small extension from edge of the metal plate but what about those 90 if you have any idea?

Yes, I know 140mm concrete ceiling slab may sound ridiculous for mounting hospital pendants. I m pretty sure there should be something above that slab probably another concrete layer and some insulation layer connecting together. Because this is already a completed project so the pendant is there and it works anyway.

The biggest problem is I don't know where are some numbers come from??? That makes a big headache to me