Popping Noises in Parking Garage?

[bbuzzell]

We have a client that owns a 2-level parking garage, Chicago area. The framing system for the upper level is your typical double-tee-on-inverted-tee, with the inverted tees sitting on corbels on precast columns. Typical double-tees are 12' wide by 60' long. The structure is 8 years old.

Recently residents have reported hearing 'popping' noises in the structure, and one even described it as a 'boom' with a vibration. We went out there and witnessed this for ourselves. The closest sound I can think of is that of a car door slamming shut. It seemed to be coming from random locations, hard to locate exactly because the sounds were echoing around the place. The frequency was random too, from 2-3 seconds to a minute or more.

Hopefully one of the parking garage experts out there can explain this phenomenon to me. Is this due to thermal expansion? (We were there late morning on a sunny day) If so, then does it mean the bearings aren't functioning properly? Something must be getting caught on something else, then releasing as the pressure builds up. But is this normal? We did the inspection on this structure this past summer, and saw no physical damage anywhere that would lead us to believe there was a problem.

Any kind of insight would be greatly appreciated. I'm not ruling out the possibility that this structure is haunted.

Thanks,
BB

 

[hokie66]

I agree that the most likely cause is thermal sliding, and don't consider the noises to be "normal" or acceptable.

 

[FoxSE14]

I'd check out the bearing pads - could be that the pads are not properly installed/specified and are moving suddenly after sufficient pressure build up during thermal cycling as you mentioned. These pads frequently "walk" their way out of the joint if not properly installed/specified.

I'd also check out the shear connectors (sometimes aka "flange connectors") at the double-tee joints. You say the structure is 8 years old? At this point in the garage's life, it could be that some of these have failed due to corrosion from exposure to de-icing salts and are simply moving in response to tire traffic as cars drive by. One way to check for failure of these connections, besides visual inspection, is to stand over a joint as a car drives by - you'll feel the relative motion of the tees as the car transfers it's weight from one member to the other. Shear connector failure is widespread in precast garages throughout the upper midwest.