Glass Railing Concentrated Load

Log Out | Topics | Search Moderators | Register | Edit Profile

Author Message Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1128 Registered: 05-2003 Posted on Saturday, July 12, 2014 - 05:55 am:    I've been told the following excerpt from my spec section for Glass Guardrails is incorrect, that the concentrated load should be 400 lbs. Can any of my learned colleagues tell me if this is true and when this changed? "Infill Area: Capable of withstanding a horizontal concentrated load of 200 lbs. per linear ft. applied to 1 s.f. at any point in the system, including glass panels, intermediate rails, balusters, or other elements composing the infill area." Thanks to all who respond, I appreciate your guidance on this one. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1582 Registered: 03-2002 Posted on Saturday, July 12, 2014 - 11:26 am:    As far as I know, glass guardrails don't have different load requirements than other railings and guards (1607.8 of IBC). However, railings supported by glass must span three glass balusters per IBC 2407, bu I see 2407 has a somewhat new exception to that provision allowing laminated glass in lieu of the three baluster rule. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1130 Registered: 05-2003 Posted on Sunday, July 13, 2014 - 06:27 am:    OBI WAN RON GEREN, oh knowledgeable one, I would appreciate your 2 cents on this: In FBC, Chapter 16: 1618.4.6.3 allows for the use of laminated glazing providing that the it can resist 400 lbs., my client is asking for my opinion on this, my peers and I are specifying 200 lbs, so who is right? Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 670 Registered: 10-2007 Posted on Sunday, July 13, 2014 - 12:09 pm:    The question seems to be what is the applicable building code for the project. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1131 Registered: 05-2003 Posted on Sunday, July 13, 2014 - 12:20 pm:    FLORIDA BUILDING CODE, 2010 EDITION Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1241 Registered: 03-2003 Posted on Sunday, July 13, 2014 - 12:25 pm:    Oh, Anakin Lazar, don't you know the difference between a concentrated load and a kenetic energy impact load? Section 1618.4.6.3 (which is unique to the Florida Building Code [FBC] for those who don't know) states that glass railings shall withstand a kenetic energy impact load of 400 foot-pounds per ANSI Z97.1. A kenetic energy impact load is a load against an element based on the weight of an object increased by the energy of object when in motion. A concentrated load is just a standard static load placed on the supporting element. For example, placing a baseball on your head is a concentrated load; throwing the baseball at your head is a kenetic energy impact load (which do you think will hurt most?). ANSI Z97.1 has three classes of safety glazing: A, B, and C. Each is tested using a 100-lb impactor, but at different heights. Class C is at 12 inches, Class B at 18 inches, and Class A at 48 inches. A foot-pound is the force of one pound displaced by one foot. Since ANSI Z97.1 uses a 100-lb impactor at 48 inches (i.e. 4 feet), the energy is 400 foot-pounds. In other words, they are requiring a Class A rating per ANSI Z97.1. Why they didn't just say that is beyond me--maybe they wanted to show their knowledge of physics. The 200-lb concentrated load is completely different. That just requires placing a 200-lb load against the railing, but it is not an impact load. In other words, understand "the Force." Does this answer your question, young Jedi? Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1132 Registered: 05-2003 Posted on Sunday, July 13, 2014 - 12:30 pm:    I hated Physics, loved the teacher though. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1133 Registered: 05-2003 Posted on Sunday, July 13, 2014 - 01:23 pm:    Thanks Ron, your insight is always valuable, I appreciate you taking the time to respond and comment. Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1242 Registered: 03-2003 Posted on Sunday, July 13, 2014 - 01:41 pm:    Jerome, I don't understand Florida's need to add that requirement in Chapter 16, when Section 2407.1.4 already states that glass railings must be tested to comply with either Class A of ANSI Z97.1 or Category II of CPSC 16 CFR 1201 in wind-borne debris regions. Granted it applies to exterior railings (the FBC seems to indicate that it applies to all glass railings, interior and exterior), but that could easily be amended. Since Florida didn't amend that section, it appears to create a conflict (i.e. exterior only or all glass railings?). They could learn from CSI: Say it once and in the right place (ICC is also culpable in that regard). Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1134 Registered: 05-2003 Posted on Sunday, July 13, 2014 - 01:54 pm:    Its also covered in the 2407.1 under Glass Handrails and Guards. There seems to be a lot of redundancy in building codes, FBC is no exception. In my case, I failed to stipulate Class A, but I did require compliance with ANSI Z97.1 and 16 CFR 1201; based on your input I am going to update all my Glass Railing specs to include Class A specifically. Thanks again OBI WAN GARREN.