Facade Issues in Steel Buildings
Of special note to anyone who been working with facade connections in steel buildings is two documents from AISC. The first is their “Design Guide 22: Facade Attachments to Steel-Framed Buildings” and the other is a recent article in MSC: “Steel Framing & Building Envelopes”.
The Design Guide 22 is free to AISC members (~$60 otherwise) and is probably one of their best. It has a great amount of information about spandrel beams, connections, facade issues, and even backs it up with some FEA work.
The MSC article “Steel Framing & Building Envelopes” by James A. D’Aloisio, PE, SECB, LEED AP should be considered as an addendum to the design guide, specifically dealing with the issues of thermal bridging and building envelope thermal performance. Basically, if an engineer applies the suggestions from DG22 without considering thermal bridging effects, then the R-value of the wall assembly could be halved (!).
D’Aloisio’s has published some interesting details he is experimenting with. His recommendation is to always use a thermal break, and he shows a Fiberglass-Reinforced Plastic shim plate to isolate steel lintels and hangers from the exterior environment. As he points out, many LEED NC buildings are not meeting their expected performance levels. The reason may be because of conventional details used by the construction industry.
