HomeMy WebLinkAboutFile Documents.634 W Hopkins Ave.0106-2021-BRES (19)Edward C. Robison, P.E.
16 OCT 2019
C.R. Laurence Co., Inc.
2503 East Vernon
Los Angeles, CA 90058
SUBJ: CRL SRS STANDOFF RAILING SYSTEM
GLASS BALUSTRADE GUARDS
The SRS Standoff Railing System is a guardrail system that utilizes point supported glass
balustrades. When constructed in accordance with the attached details and installation guidelines the
guardrail can designed to safely support the following loading conditions:
200 pound point load on top rail, vertical or horizontal or
50 plf load on top rail, vertical or horizontal or
25 psf uniform load on glass panel horizontal or
50 lb conc load on 1 sf or
Wind load - As listed with respect to glass size or determined by FEA modeling
Typical glass thickness: 3/4” monolithic or 13/16” laminated minimum thickness.
For exterior installations wind loads and glass stress must be calculated by a qualified
licensed engineer.
For single family residential construction only the 200# concentrated top rail load, 50# concentrated
load and wind load (exterior) are applicable (non-concurrent).
The SRS is to be used with tempered glass only, laminated or monolithic. Laminated glass must be
made with Kuraray SentryGlas+ interlayer or an equivalent ionoplast interlayer.
Glass light stresses were evaluated using finite element analysis (FEA) with SCIA Engineer 18.1 in
order to derive rules for designing a code compliant system. Generally, a qualified licensed engineer
must evaluate a specific installation for code compliance using a FEA model or other recognized
method.
All results given in this paper are based on the assumption that the top rail has inadequate strength
and stiffness to cause significant load sharing between the glass lights except as specifically stated
herein. Added support from stronger and stiffer top rails that anchor to posts or walls independent of
the glass balustrade may significantly reduce the glass stresses and deflections. When designing a
glass balustrade with the additional support a FEA model should be used which accounts for the
proposed specific conditions.
The recommendations herein are intended to assist a qualified licensed engineer in developing a code
compliant guard that meets the applicable requirements of the 2009, 2012, 2015 and 2018
International Building Code and state codes adopted from the IBC codes. This paper is not intended
to demonstrate the code compliance of an installation but is to only be utilized by the qualified
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98335 fax 253-858-0856
email: elrobison@narrows.com
CR Laurence Standoff Rail System – SRS 10/16/2019 Page of 2 31
licensed engineer in charge of the glass balustrade guard in analyzing the glass stresses and
anchorage.
This paper only evaluated 2 and 3 standoff pairs per light. Additional standoffs may be used and will
decrease the glass stress. If additional standoffs are proposed a FEA model should be used to
determine the glass stresses, deflections and standoff reactions.
Notes on developing an effective FEA model:
When developing a FEA model the glass stresses are very sensitive to small changes in the boundary
conditions and how the supports are represented. It should be assumed that the clamping at the
standoff fittings when using the fittings in this paper will provide reaction points at the horizontal
centerline of the edges of the holes. No significant moment resistance will occur at the standoffs so
that the reactions should be modeled as surface bearing only. Moment resistance is provided by the
force couple developed between the two standoffs in a pair. These recommendations are based on
creating a FEA model that is consistent with the results of physical testing by CRL
The standoffs must always be used in vertical pairs. Vertical loads should be assumed as acting on
only a single standoff in each pair, and only on two standoffs when more than 2 pairs are used.
Table of Contents
Signature Page 3
Glass Strength 4 - 5
Glass Panel Loads 5
Allowable Wind Loads 6 - 13
Guard Rail Applications 14 - 15
Glass Standoffs 16 – 17
Custom Standoff lengths 18
RSOB20 Fitting 19
Grab Rails and Cap rails 20
FEA Result Tables 1/2” glass 21 - 31
Edward Robison, P.E.
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98335 fax 253-858-0856
email: elrobison@narrows.com
CR Laurence Standoff Rail System – SRS 10/16/2019 Page of 3 31
Signature Page:
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98335 fax 253-858-0856
email: elrobison@narrows.com
42123EDWARD C.
ROBISON
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REGIST ERE D
Edward C. Robison
088030
EXP 03/31/2021
EXP 03/31/2020
EDWARD C.
ROBISON
12/31/2019
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NO. 63683
STATE OF
EXP 02/28/2021
73556
EDWARD C. ROBISON
EXP 09/30/2019
EDWARD C.
ROBISON
STRUCTURAL
No. 49757
EXP 06/30/2020
No. 10738527-2203
EDWARD C. ROBISON
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Professional Certification. I hereby certify that these
documents were prepared or approved by me, and
that I am a duly licensed professional engineer under
the laws of the State of Maryland,
License No. 52500, Expiration Date: 04/09/2020
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THIS WORK WAS PREPARED BY ME OR UNDER MY SUPERVISION
04/30/2020
Signature Expiration Date of the License
ED W A R D C.ROBIS
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LICENSED
PROFESSIONAL
ENGINEER
No. 11576-S
EDWARD C. ROBISON
Lic No. 059203
OREGON
18195PE
EXP 12/31/2020 FIRM #F-12044
EXP 12/31/201921