As many of you know, my oldest daughter (and early adopter of mobile credentials) recently graduated from the University of Tennessee in Knoxville.  When I attended the UTK Honors and Scholars graduation event, I noticed an interesting application that I’m sharing in today’s Fixed-it Friday post.

Here is an exterior view of the Student Union, showing the curtainwall system spanning multiple floors.

There is a large atrium in this portion of the building, and for most atrium applications, the International Building Code (IBC) requires the installation of a smoke control system.

University of Tennessee in Knoxville Glass atrium

Many smoke control systems use automatic-opening doors to provide the necessary airflow when the system is initiated.  I have worked on many projects where the pedestrian doors were equipped with automatic operators that interfaced with the smoke control system to open the doors upon activation of the system.  I could not tell if these entrance doors operated that way, or whether the operators were provided for accessibility and convenience purposes only.

Along the wall pictured in the exterior photo, there are several pairs of doors with no visible hardware.  The purpose of these doors is to open automatically (via a “blow-open” system) to provide the make-up air for the smoke control system.  I had an inkling about the invisible locks, so I contacted Bill Trimble of the William S. Trimble Company to get more information.  I guessed correctly – the doors are equipped with shear locks – a type of electromagnetic lock.  As I mentioned in a 2009 post that includes a video of a shear lock in action, I do not typically recommend this type of lock because of the need for very crucial alignment (among other reasons).  These doors, which are rarely opened and are likely supervised when they are closed at the end of a smoke evacuation event, would be one of the few applications where I might use shear locks.

These doors are not required exits nor are they provided for egress purposes, so they are not required to comply with the code requirements for doors in a means of egress.  The doors are not marked with exit signage, but the university went one step further and added signage stating that these doors are not exits.

I’m guessing from the push button mounted on the mullion that the doors are sometimes opened by university staff and left in the open position to allow easy access to the exterior area, but the actuators are positioned so that they are less likely to be used by an unauthorized person.

What do you think of this application?

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