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Re: Structural glass design

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Adolfo,
Thank you for comments. Now more specific question:
The minimum recommended length of setting blocks from Neoprene is 10% of square footage of the glass panels but not less than 4". Also the maximum compressive strength of silicone blocks is limited to 60psi. But the architectural requirements doesn't let such lengths to satisfy these requirements. Do you know any other design values that let me use harder materials? And how can I measure the effect of bearing stress on the glass? Is ther any limitation for chamber dimension at the glass edges?
Thanks,
Fariborz Tehrani,                      Phone: (310)509-8826
Civil Engineer                           Fax: (530)481-9532
BSCE, MSCE, PE                    Voice Mail: (877)743-6206
email: fmtehrani(--nospam--at)hotmail.com



From: Adolfo Galvez <agv(--nospam--at)amauta.rcp.net.pe>
Reply-To: seaint(--nospam--at)seaint.org
To: seaint(--nospam--at)seaint.org
Subject: Re: Structural glass design
Date: Sat, 04 Dec 1999 13:39:10 -0500

At 03:05 PM 03/12/1999 PST, you wrote:
>Hi everybody,
>Does anybody know a reference regarding structural glass design. Glazing
>Manual of GANA and AAMA publications have some data for flextural modulus of
>rupture and also practical recommendations. But I'm looking for more data
>regarding compressive, tear-out and bearing allowable stress for structural
>glass panels to use in a rational analysis and design procedure. Also any
>data regarding glass supports design, such as design stresses for setting
>blocks will help.
>Thanks in advance,
>
>
>Fariborz Tehrani,                      Phone: (310)509-8826
>Civil Engineer                           Fax: (530)481-9532
>BSCE, MSCE, PE                    Voice Mail: (877)743-6206
>email: fmtehrani(--nospam--at)hotmail.com
>
>______________________________________________________

Dear Fariborz:

I dont know any reference, but here is some comments from past designs:

Glass is a fragil material, as GANA and AAMA say you need to use a Failure
Probability concept to design glass.

After modeling your structure, select a Limit State to check. Use a normal
distribution for glass strengh, a 25% cov is ok.

Select proper pdf parameters for random variables to use for DL, LL, WL and
EL. DL is normal, 10% cov., LL is gamma, WL is EVD type II, and EL is EVD
type I.

ANSI: "Development of a Probability Based Load Criterion for American
National Standard A58" is a very usefull source of info in random pdf data.

Your reliability Index shall be according to ANSI:

3.00 for DL + LL

2.5 for WL+LL+DL, (look it is almost the same as 8/1000 breaking lites in
GANA and AAMA, for wind design of glass and 2.5 as design factor)

1.75 for EL+DL+LL.

If the glass is supported on structural silicone, like in two or four sided
Curtain Wall systems, you need to do a non linear analysis, to simulate the
effect of the silicone bedding.

If you are supporting on polymer blocks, be carefull to look the glass
never be in contact with the supporting frames, it will break.

Try polimer as springs, but also need to model the silicone used to fill
the joint between glass and supporting structure.

Excuse my grammar, my english is not good¡

Regards,

Adolfo Galvez MSc., PE

Lima, PERU




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