The Use of Glass as a  
Structural Material is  
Growing; Here’s What  
YbyoElluen RNogeersed to Know  
tructural glass isn’t for every- increase in larger and larger pieces of  
one. Even after decades of proj- structural glass has opened the pos-  
ects, some architects, designers sibilities to embrace the transparency  
and contract glaziers are still hesitant of glass.  
to take on these jobs.After all,these de-  
“We’re seeing such tremendous growth  
signs use glass in ways and places that in manufacturing capabilities that it’s  
no one would have ever imagined— transformed what we can do with glass  
like the glass staircase in Apple’s first [having the ability to design] frame-  
Flagship store in Soho, which opened less glass structures that use structural  
in 2002. Since then, the tech giant silicone and minimize the opaque ele-  
has shown its love for glass in stores ments on the façade has created wonder-  
around the world. And, as fabrication ful opportunities,”says Orsega.  
technologies and capabilities have in-  
creased, so has the glass.  
Eckersley O’Callaghan (EOC) is the  
engineering firm that’s worked closely  
Structural glass projects are becom- with BCJ on many structural glass proj- the ordinary. Then you start to look  
ing more common, but not everyone is ects. EOC associate Marcin March is for the next aspiration.”  
ready to jump in.It takes a team willing leading the newly launched San Fran-  
Richard Green is a principal with  
to challenge the design limits and an- cisco office. He says structural glass Front Inc., an architectural design and  
swer the “what ifs.” There’s a lot to un- has grown to a level of precedent that’s consulting firm, that has worked on  
derstand—and the question of what’s helped increase awareness and interest. major glazing projects all around the  
next, is still waiting to be answered.  
“We’re putting glass on par with more world. He also attributes recent devel-  
traditional building materials (brick, opments in technology as reason for  
concrete, stone, etc.),” he says. “Having the increased interest.  
New Developments,  
New Opportunities  
precedent has done a lot to move that  
“The improvements in glass and  
The industry has seen tremendous along to where people can see using it lamination technology mean that you  
advances over the past decade-plus where it wasn’t used before.”  
can design glass to be robust in a way  
since glass was first used as a struc-  
He adds that the early applications that was not common previously. This  
tural component. Demand for more have evolved to become more com- has facilitated some very high pro-  
glass and less metal spurred glazing plex. “And as you continue to build file glass projects, which has in turn  
product suppliers, designers and en- on that, it creeps into normalizing the given the public confidence in using  
gineers to develop solutions to meet more ambitious stuff, making those glass structures,” he says. “Structural  
these requests. As a result, the growth installations more commonplace,” glass has become architecturally aspi-  
and interest flourished.  
says March. “That’s helped advance rational and as more fabricators gain  
Christopher Orsega is a senior as- growth, as well as more people trying the capacity to produce specialist el-  
sociate in the San Francisco offices of their hand at building and designing, ements, structural glass has become  
Bohlin Cywinski Jackson (BCJ), the so there’s now more who can do it. more accessible.”  
architectural firm behind many of Enough time has passed since the first  
Apple’s glassy retail stores. He says the few installations that it’s not so out of  
continued on page 44  
USGlass, Metal & Glazing | April 2017  
Structural glass has become  
architecturally aspirational and  
as more fabricators gain the  
capacity to produce specialist  
elements, structural glass has  
become more accessible.  
—Richard Green, Front Inc.  
Designed by Renzo Piano Building Workshop/Betaplan, the  
features a 75-foot-tall glass fin supported glazing system  
with the glass fins partially engaged in the exterior envelope.  
Front Inc. provided system design and analysis services from  
concept design through construction administration.  
April 2017 | USGlass, Metal & Glazing  
Steps Toward Success  
“How’s this thing going to work?”It’s  
probably a question that’s been asked  
more than once. That’s okay, but it  
needs to come at the right stage—the  
sooner the better.  
March says that at his firm projects  
sometimes come from the architect or  
from a contractor, who has a concept  
from the owner “that’s not documented  
and hasn’t been designed because it’s de-  
sign-build and they may not necessarily  
know how to approach engineering it.  
They don’t necessarily have the ex-  
perience … in considering structural  
glass as element in itself and need  
help with the design work,”he explains.  
With architects, he says that ideally  
the design will be as realized as possi-  
ble in terms of the mechanics—size,  
shape, details, etc.  
If it’s a straight staircase it’s fairly sim- The 5th Avenue Apple cube, designed by BCJ with EOC as the engineer, was  
ple,but when it starts turning corners,for first built in 2006 with 90 panels of glass. Thanks to new developments in  
example,you can get into lots of details as structural glass technology, as well as the availability of larger panels from  
you go around and that’s sometimes left Sedak, the cube was rebuilt in 2011 with only 15 panels and 40 fittings.  
for the contractor or engineer to figure  
out,”March says.“So by the time the con-  
“The glass has to accommodate we control the non-transparent elements  
tractor gets his hands on it,you could get those movements without stiffening that let glass’s inherent properties shine?  
compromised details—details that work the building itself. These movements Are there limits to what we can do with  
technically, but may not be as resolved need to be taken into account … often exposed edges? What are the restrictions  
architecturally as they could be.”  
that’s one of the last things looked at in terms of structural durability over  
He continues, “From the contractor and should be one of the first. It should time that limit/don’t limit those oppor-  
side, usually they’re more pragmatic be looked at early on in the process tunities,”he says.“We rely heavily on our  
because they want to get it built. There’s rather than having to retrofit the build- engineering partner and they come to the  
no variation from the design unless it’s ing to accommodate the objects. Often, table a lot with answers,but we also know  
necessary to make it work.So what we’re retrofitting additional support struc- the industry is changing quickly and the  
looking at is, does everything work as a ture cannot be avoided, but it’s best to manufacturers are on the front end.”  
whole from the architect side and does it have this known ahead of time rather  
From the installer’s perspective, Joe  
Lucin, principal at Mistral Architec-  
stand up from the contractor side.”  
In any case,attention to detail is crit-  
ical in every phase of the design.  
than a last minute addition.”  
Planning is also important to the tural Metal + Glass Inc. in Woodside,  
installation. N.Y., says one challenge they often face  
“You can’t tweak [the work] on site if involves poor design details. He says  
When designing with glass you  
need to consider every load, every it doesn’t fit,”says March,explaining that they often have to redesign parts of a  
movement, every clearance and every planning ahead of time helps you un- project because they have either been  
tolerance,” says Green. “In metals, if derstand what could go wrong,so issues poorly detailed or don’t work aesthet-  
something is a bit out it can bend or can be addressed before they happen.  
yield and still be structurally sound. Orsega says that, from the architect’s  
ically or structurally.  
“We feel projects would go smoother  
Glass is less forgiving so you have to perspective,much of what they’re look- if there was more thought that went  
think about all the possibilities in ing for is an understanding that goes into the design,” he says. “If you’re de-  
advance. A lot of planning goes into beyond size constraints.  
signing and don’t know how something  
structural glass assemblies.” “If we’re designing with glass fins,what will be built and with what product,  
March points to external factors is the nature of/constraint we have in you didn’t do your job.”  
that affect the design, such as building terms of structural silicone and how it’s  
movement, as an example.  
used in conjunction with glass? How do  
continued on page 46  
USGlass, Metal & Glazing | April 2017  
Know What You’re  
Working With  
and answer the question of how to make of the glass elements and the type of  
these super sizes work smartly from a systems in which they function.”  
Even when the interest is there,struc- sustainability stand point.  
He says the standard will provide for  
four glass risk categories, ranging from  
fruition.And that’s primarily due to cost. Enter the Comfort Zone no post-fracture requirements, through  
Structural glass projects continue to increasing retention and redundancy re-  
tural glass projects don’t always come to  
“Some projects will be going well and  
then they (e.g.,owners) look at the num- take shape in today’s architecture, and quirements appropriate to the circum-  
bers and see it as [too much] of an in- we’re just beginning to see the possi- stance and consequences,up to the most  
vestment,”March says.“… the challenge bilities. Lucin expects to see designers robust class where post-failure capacity  
is that the price depends on the details. continue to push the boundaries of requirements are outlined.  
You can do it inexpensively … but if what can be done with glass.  
“It will allow the specifier to select a  
you go for something more bespoke that “I think there will be more daring level of performance they require, and  
can raise costs significantly.You need to structural glass staircases, along with will allow the industry to classify the  
know the budget you’re expecting and more innovative structural glass store- more robust and sophisticated systems  
the range that could fall in, so you can fronts,” he says.  
manage clients’ expectations.” Despite the interest, structural glaz- ognition over less robust options,” says  
Early involvement with all parties can ing still faces some obstacles. One of Green. “Most importantly, it will pro-  
help ensure staying within the budget.  
the biggest is that many contract gla- mote the continued growth and confi-  
Everyone involved with a structural ziers aren’t comfortable doing this dence in structural glass by architects  
glass project must act as a team: the type of work. This lack of familiarity and the public alike.”  
architect, the designer, the fabricator is a challenge.  
EOC is also involved with these ef-  
The development of codes and stan- forts.March agrees that codes and stan-  
they are selling to gain commercial rec-  
and the installer,” says Green. “The  
sizes and technologies available are dards could help. Work is underway dards can help bring structural glass  
changing rapidly. A good designer can within ASTM to develop a guide for into the mainstream, mitigating risk for  
guide architects to achieve their aspi- the structural use of glass in buildings. installers and increasing awareness.  
rations through knowledge of what can Green has been heavily involved, and  
“However, it also limits those of us  
be fabricated, what can be constructed says while traditional glass standards who’ve been doing it a while,” he says.  
and how to make it safe. Advanced en- around the world have been concerned “It does err on the conservative side.  
gineering plays a vital role in getting with the strength of glass in windows While it’s good to normalize structural  
it to work on paper. The glazing con- and the strength of the material to pre- glass, it’s also a risk that can hem us  
tractor is a key member of the team vent initial cracking,“few of them deal in to being too simple and limit what  
and it’s good to have them involved with the requirements of post-fracture we can do. It’s a balance to maintain;  
throughout the design development or only do so to control falling mate- things that become more standardized  
because they are the ones that have to rial.” He gives ASTM E2751 for glass do come with more restrictions and  
build it.” He adds that it’s also import- walkways or the hurricane glazing [projects] could become less ambi-  
ant for contract glaziers to understand provisions as examples that consider tious. On the flip side, the more that is  
the subtleties of the design and that post-fracture.  
the design considers the practicalities “However, when it comes to the  
built the more the field can evolve.”  
He points out that the ambitious  
of building it.“To achieve the best from broader use of structural glass, there work we’re seeing today is only possible  
modern glass design, everyone has to currently is very little design guidance because of the simpler work that came  
be involved and committed to giving for the architect, designer, glazier or before it.  
the most to the project.”  
Orsega sees future opportunities for  
building authority.  
“There are times where monolithic on what’s been done before … Is there  
“You can have new ideas and build  
structural glass in building envelopes, glass without post-fracture capacity is a limit? We don’t know. We haven’t  
particularly as an environmentally re- suitable and there are times when more reached it yet.” n  
sponsive material.  
robust design is desired,” says Green.  
Large,transparent spaces are difficult “The [ASTM] committee has been  
to condition, so I think one of the really working for several years to come  
interesting challenges is how to advance to consensus on what is appro-  
the engineering of glass itself (its own priate and hopes to have a draft  
composition) in a way that it becomes out this year. The standard aims  
environmentally responsive,” he says, to provide distinctions and min-  
adding that exploring opportunities with imum requirements based on the  
opacity, shade, etc., could be fascinating circumstances and consequences  
E l l e n R o g e r s is the  
editor of USGlass magazine.  
Follow her on Twitter @  
EllenGRogers and like her on  
Facebook at usgellenrogers  
to receive updates.  
USGlass, Metal & Glazing | April 2017  

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