TR2 Completes AMC Theater Structural Roof Survey

A red-eye from Los Angeles to Atlanta got me to the airport at 6:00 am. A hotel catnap and my local surveyor's car got us to the AMC theater 15 minutes ahead of schedule. I was looking forward to this.

The projection room was vacant, but the theaters were occupied with a healthy weekday afternoon crowd, spending time together, enjoying the air conditioning and watching the movies. The old film reel tables were there, as well as the conveyors for carrying the film reel from theater 3 to theater 9 for the next showing in 20 minutes. The serpentine corridor-like room weaving between the back-to-back theaters, once traversed back and forth, back and forth, by a couple of projectionists with eyes glued - one to the movie schedule and one to the clock, is now stacked with satellite-connected computer servers and digital projectors.

What a "cool" room (not as in AC cooled) these projectionists had as their secret domain! There are a number of current articles lauding these technicians and lamenting their passing. For more from a projectionist, see "The Last of the Real Live Projectionists". For a slide show of images from projector rooms, try this one from NPR (and don't miss the comments from authentic projectionists). For observations on the current transition from celluloid to digital, see "Where Have All The Projectionists Gone?" And lastly, for a nerdy blog among projectionists that might awaken your inner projectionist, try this. As I write this, I can almost imagine their happy ghosts lingering, longingly, lovingly, in these back rooms of theaters, their secret place, facilitating the entertainment of millions. I stepped closer to peek through the little glass pane through which the projector was throwing the current film onto the theater screen. Quickly stepping back I said, "Digital or film, those projector bulbs still get hot!" "In the Summer, it gets unbearable in here," the Facilities Manager said. "It's not good for the equipment and it's not good for the service technicians. That's why we're installing the new HVACs. Come on, let me show you where."

Through a nondescript door we were now in the backside, underbelly shell of the mall. Down a flight of stairs and then another flight. Back out into the mall space filled with customers. The original mall was built in 1961 with a major expansion in 1991 including two additional wings. The logistics of interlinking the service corridors were obviously challenged by the expansion. "Sorry for the long walk and climb," the manager offered. After the 5 hour plane ride, this was good exercise. "Not a problem," I said. Through another door and up a flight of stairs. Down along a winding corridor with painted doors every 50 or 75 feet. "These doors open into the backside of the mall stores." Up two more flights of stairs and though a door. The door opened onto a brilliant sunshiny day, made almost blinding by the combined facts of the exit from the long walk in darkened corridors and the pure white roofing material recently installed. I squinted through my sunglasses and we all took a moment to let our eyes adjust.

"Here, and....." he walked over approximately 70 feet, "Here. This is where where we want to place the new RTUs." I nodded, scanned the accumulation of other equipment scattered across the roof, and asked, "Do you have flexibility to adjust the locations plus or minus 10 feet if that suits the structure better?" "Sure, no problem." "Alright", I said, "I think we'll be able to work out a solution for you."

Van Heusen Outlet, Orlando, Roof Structure Submittal Completed

The Roof Reinforce, TR2 Inc, completed its submittal for the building deparment for this national retailer. "The client is upgrading the HVAC equipment mounted on the roof," said Tim McCarthy P.E., chief engineer for TR2. It's a routine project for us. We were able to turn it around rapidly for the client."
TR2 supplies structural services for Retailers and HVAC contractors nationwide.

Sears, Texas, Roof Structure Engineering Report Completed

TR2, The Roof Reinforcer, completed and submitted its final evaluation report for this eastern Texas major retailer today. Tim McCarthy P.E. was consulted to investigate a deflected 20T RTU mounted on the roof. "We performed two site visits altogether," said Mr. McCarthy, principal with The Roof Reinforcer. The first visit yielded measurements of deflections at the top of the RTU and the surrounding roof membrane. The second visit was necessary to measure structural element elevations inaccessible without proper equipment."

The project required two weeks to investigate the structure, analyze the acquired data and develop conclusions.

"The deflection in the roof mounted equipment was obvious," noted Paul, Southern Region Project Manager for TR2. "And there were elevation divergences in the roofing measurements and the structural supporting elements too. But what was unusual was that the RTU measurements and the roof top and structural measurements were telling two different stories. The RTU measurements indicated an unacceptably large deflection to one side, unacceptable from the viewpoint of HVAC performance. The structural measurements corresponded in direction but were much less in magnitude, a magnitude that was well within design standards." The expected solution, an inadequate structural roof system for the support of the HVAC, was not indicated by these measurements. Further investigation was indicated.

Tim McCarthy P.E.: "We performed calculations of the center of gravity of the 20 ton RTU in relation to the supporting structure and found it to be significantly off center, about 50%. We further discovered that the mounting system was significantly smaller than the HVAC base. The combination of these two geometries renders this particular RTU significantly vulnerable to laterally imposed loading conditions." Further investigation revealed that this store was within the current code prescribed hurricane region and likely subject to significant wind gusting.

"This appears to be a classic case study for the significant acceleration in recent codes of wind loads on roof mounted equipment," noted Tim McCarthy. "It's only been since 2000 that industry research and the building codes have directly addressed wind gust loads on roof mounted equipment. And the results have been surprising. Current wind codes mandate design loads frequently double or even triple what many current buildings have been designed for."

The report recommends a contemporary wind analysis be performed for this deflected RTU, that a proper load distributing curb be designed, and anchorages installed in accordance with the wind design.