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Curtain Wall Design

kodstruct

(Structural)

(OP)

20 Mar 15 23:37

Hi there,
Lately I have been getting calls from contractors to design curtain walls and storefront systems for them. So I am thinking to start my practice in the area.
Is there a good software out there for this?
Thanks.

Replies continue below

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RE: Curtain Wall Design

jike

(Structural)

20 Mar 15 23:59

There is a definite need for engineers to design light gage framing. Our office typically would design projects with only a few light gage elements but if it was a large job we would put it under the responsibility of the contractor. Since I retired over a year ago, I cannot remember the names of software. You also need to develop some standard details.
Good Luck!

RE: Curtain Wall Design

kodstruct

(Structural)

(OP)

21 Mar 15 02:00

thank you Jike. What about the aluminum curtain wall/storefront system?

RE: Curtain Wall Design

Ron

(Structural)

21 Mar 15 03:39

kodstruct...most any good FEA software will do. There are some dedicated software packages for light gage design (Check with Dietrich.....they supply light gage framing materials and I believe they have software as well.). If there will be aluminum and glass involved (storefront/curtain wall), you'll need Window Glass Design 5 for all the calcs required to comply with ASTM E for the glass.
I have used RISA 3D for light gage framing analysis and design. I use it for lots of other stuff as well.

RE: Curtain Wall Design

kodstruct

(Structural)

(OP)

21 Mar 15 13:07

Thanks Ron... I use SteelSmart for metal stud or light gauge curtain wall design.
However I am looking for a software for aluminum curtain wall and storefront system, capable of designing mullions, and coming up with shop drawings.

RE: Curtain Wall Design

Ron

(Structural)

21 Mar 15 13:16

Check with Kawneer or YKK...they can tell you packages you can use. Be careful of dedicated package software...they are usually limited and proprietary.

RE: Curtain Wall Design

kodstruct

(Structural)

(OP)

21 Mar 15 14:54

Fantastic Ron.. Thanks.

RE: Curtain Wall Design

glass99

(Structural)

22 Mar 15 02:09

Curtain wall structural engineering is a whole specialty. The basic calculations are conventional beam theory, but there is a bunch of nitty gritty bits and pieces you have to learn. Fasteners are a big one (TEKS Screws, stainless bolts, machine screws, etc. You finish up with a lot of weird plastics. There is the glass. You need to get familiar with the Aluminum Design Manual. Custom extrusions can be a bit tricky with buckling.

RE: Curtain Wall Design

kodstruct

(Structural)

(OP)

22 Mar 15 03:27

@ glass99,
Do you give any suggestion for any software out there?
You know how it works; once you do a couple designs with the right manual you get it. I would like to start my practice in specialty structural engineering like connection design, light gauge curtain wall design, certified welder inspector and storefront design. There is a huge market because many firms don't design those things including the firm I am currently working at.
What I see so far, the revenues are more than typical structural engineering design.
Thanks.

RE: Curtain Wall Design

glass99

(Structural)

23 Mar 15 15:58

kodstruct: If you are looking for software that automates a lot of the checks involved in curtain wall design, there is not one that I know of. I use Strand7 (FEA), Window Glass Design (glass structural), DrBeam (1d beams), ACAD, Rhino, SolidWorks, Hilti Profis. A lot of people like MEPLA for glass, though I don't use it. SAP has automated aluminum design features which I have heard of some people using. I will caveat this by saying aluminum extrusion related work is less than 5% of what I do. I am more of a structural glass guy.
Curtain wall design can be a good business, or it can be terrible.

RE: Curtain Wall Design

RFreund

(Structural)

23 Mar 15 17:39

Quote (glass99)

Curtain wall design can be a good business, or it can be terrible.

Could you elaborate?

Could you elaborate?

EIT
www.HowToEngineer.com

RE: Curtain Wall Design

glass99

(Structural)

23 Mar 15 21:44

I know facade consultants that drive Porsches and others who can barely afford gas for their '98 Camry. There is huge variation in fees for similar work, and it revolves around the attitude of the consultant. Client side and contractor side have pretty different schtick's. Generally client side is better, but not always.
The two things that make you valuable are the perception that you are either a rock star who's gonna make it awesome, or a Guardian of the Clients Rights and Specification Cop. Straight ahead calculations are kind of a commodity, but even there there are ways to do alright I guess.
To do well as a Specification Cop, you need gravitas, business sense, and an army of inspectors. To do well as a rock star designer, you need good ideas and swagger. To do well as a calc machine, you want to be as high in the analysis cleverness food chain as you can, and be efficient.

RE: Curtain Wall Design

RFreund

(Structural)

24 Mar 15 10:31

Thanks Glass!

EIT
www.HowToEngineer.com

RE: Curtain Wall Design

RFreund

(Structural)

24 Mar 15 10:45

Quick edit - You do need "J" for tubular sections but not channels. Although these typically aren't actually tubular. The section property calcs and allowable stresses get a bit intense.

EIT
www.HowToEngineer.com

RE: Curtain Wall Design

RFreund

(Structural)

24 Mar 15 21:21

Are sills typically designed to carry the dead load (and lateral load) of the glass between vertical mullions even if there is substrate below (Similar to intermediate horizontal mullions)? Usually there is a gap between the bottom sill and the substrate but you could add blocking in which case you wouldn't need to span the sill between the vertical mullions. However unless the substrate is foundation the member is probably not designed to support glass vertically. So I suppose any situation other than the blocking between foundation and sill the sill would need to span between vertical mullions, no?
Is the only connection to the substrate then typically at the T&F anchors at the vertical mullions or is the sill (or head for that matter) ever fastened to the substrate as well? I would think not, as you would want to allow for differential movement and the only way this is accomplished with through the T&F anchors, right?
Thanks!

Another question here...Are sills typically designed to carry the dead load (and lateral load) of the glass between vertical mullions even if there is substrate below (Similar to intermediate horizontal mullions)? Usually there is a gap between the bottom sill and the substrate but you could add blocking in which case you wouldn't need to span the sill between the vertical mullions. However unless the substrate is foundation the member is probably not designed to support glass vertically. So I suppose any situation other than the blocking between foundation and sill the sill would need to span between vertical mullions, no?Is the only connection to the substrate then typically at the T&F anchors at the vertical mullions or is the sill (or head for that matter) ever fastened to the substrate as well? I would think not, as you would want to allow for differential movement and the only way this is accomplished with through the T&F anchors, right?Thanks!

EIT
www.HowToEngineer.com

RE: Curtain Wall Design

Thinktanck

(Structural)

16 Jun 15 16:59

kodstruct...
I'm new to this forum. I actually joined after I read this CW thread. I'm an Engineering Team Lead for a company that designs custom unitized curtain wall. Prior to this, I was Engineering Manager for a similar company that only used stick systems (Kawneer, Efco, Tubelite, etc...) I've also done contract work for glazing and ACM panel companies. You are correct in your assessment of the industry. It is a niche. A lot of our interns or new hires have degrees in Mechanical or Structural Engineering, but there is a lot of intense facade-specific training that we give them. I'd like to know how you are doing in your "infiltration" into the CW world. lol. Maybe I can help.
Thanks

Curtain Wall Basics

Above: Aaron Blom presenting during GlassBuild America

Editor's Note: The following is based on the education session 'Curtain Walls | Design Considerations, Tolerances, and Testing,' presented by Blom at GlassBuild America, held Oct. 18-20, in Las Vegas. Find more news and coverage from the show.

In its basic form, a curtain wall system consists of insulating glass and extruded aluminum framing either installed piece by piece in the field (stock lengths), or installed using pre-assembled, pre-glazed framing and glass panels (unitized). Hybrid versions include various system options and fabrication and installation techniques that can be used to achieve specific design aesthetics as well as maximize fabrication and installation efficiency.

Regardless of the installation methods used, curtain wall systems must address five primary design considerations: structural integrity, movement capability, weathertightness, energy efficiency, and sound control.

Structural integrity

As with all types of fenestration, wind load is an important structural consideration for curtain wall systems. The more the frame deflects due to the design wind load, the more stress is placed on the assembly and the greater the likelihood of system failure and/or glass breakage. The engineering calculation used to determine maximum vertical framing deflection is L/175 for spans up to 13 feet 6 inches and L/240 + ¼-inch for spans that are greater, where L is the vertical span length. Other structural performance considerations include live load, dead load, seismic, and inter-story drift.

Provision for movement

There are multiple factors to consider when designing a curtain wall system to accommodate expected movement, including thermal expansion and contraction, movement due to wind load and gravitational forces, and movement caused by deformation or displacement of the building. Movement must be accommodated to limit the stress on the glass, framing, and anchors, and without excessively reducing the frame's 'bite' or capture of the glass.

Weathertightness

Weathertightness means protection against both air and water leakage.

Water penetration. There are two methods for preventing water leakage through a curtain wall system. One is the 'internal drainage' system utilizing weep holes in the pressure plate and face cap. The other is achieved through "pressure equalization" of the system. Basically, a pressure-equalized design ensures there is not a significant negative pressure pulling water into the system from the exterior.

Air infiltration. For obvious reasons, excessive air infiltration is less critical than water penetration but can compromise the energy efficiency of the building envelope. Industry standards limit air infiltration to 0.3 liters per second air leakage per square meter of fixed wall area (0.06 cubic feet per minute per square foot of area) when tested at an air pressure difference of 1.57 pound-force per square foot.

Energy efficiency

Curtain wall systems must meet an overall maximum thermal transmittance or U-Factor (W/m2'K or Btu/hr'ft2'°F) stipulated by applicable codes based on project location and other project-specific thermal performance requirements. Improved thermal performance can be accomplished in multiple ways, including using thermally broken framing materials, using high-performance insulating glass, and adequately insulating large spandrel areas.

Sound control

Sound Transmission Class (STC) and Outdoor/Indoor Transmission Class (OITC) are the standard methods for rating sound attenuation of glass and window systems. Using laminated insulating glass, using insulating glass with an increased airspace, and minimizing air infiltration will generally improve sound transmission - of particular concern near airports and in metropolitan areas.

Performance and testing requirements

Due to the wide range of forces that act upon a building in a particular location, physical testing for air infiltration, water penetration, and structural performance (including frame deflection limits) is often the only reliable means of verifying performance in field conditions. This testing may be conducted on stand-alone mock-ups or on completed installations, also called in-place mock-ups.

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Additional reading:
How do Aluminium Mesh Ceilings enhance interiors?