Allowable deflection of steel posts providing lateral support to glass balustrade panels 1

[ajk1]

1. Does anyone know of any published requirement, or recommendation, for the maximum allowable horizontal deflection of steel posts that are to provide lateral support to glass balustrade panels? Posts are about 1.5 m on centres.

2. We calculate the posts will deflect horizontally h/80 (1070 mm / 80 = 13 mm) under the Code specified horizontal loading (since the posts are cantilevers, this would correspond the about L/160 for a single span member). Is that ok, or should the post be stiffer to avoid cracking the glass?

 

[bookowski]

and this document from California, H/90 or 3/4" under design load:

http://www.documents.dgs.ca.gov/dsa/pubs/IR_24-1_rev02-22-13.pdf

 

[Duwe6]

Talk to the glass supplier. They will have experience with what works, and what has failed in the past.

OSHA is not a design spec; it was written by non-engineers under the supervision of politicians. And OSHA is essentially impervious to feedback, unlike ASME, API, and ASIC. Thus some stupid criteria like "withstand 200# lateral loading". To a real engineer, this means that a failure at 205# is deemed acceptable. Oops.

Handrails, per OSHA, are to be 42" - period. Thus a 46" tall handrail does not meet their criteria. Even though it is safer; at 42", at least 1/4th of American men have their center of gravity above the railing. So if the taller guy is jostled, he will flip over the railing and fall. Next time you go to a shopping mall, put a tape measure on the mezzanine-level handrail. It is taller than the mandatory 42", because their insurance carrier said it had to be; in violation of the OSHA standard. And when you apply a 250# lateral load to that rail, it will not fail, nor deflect significantly. Because 200# is idiotic.

 

[ajk1]

Thank you bookowski . Looks like I have some reading to do
I guess the Australian Standard for deflection limit has to be read in conjunction with their code loading for guards. Does anyone have that information? Ours is 50 pounds per foot of horizontal rail but not less than a concentrated load of 225 pounds (0.75 kN/m, and not less than pounds 1.0 kN).

I think the deflection limit for the glass will be dependent on how it is mounted, and how it is supported.