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How would you start this investigation?
2

How would you start this investigation?

How would you start this investigation?

(OP)
There was a partial collapse of a parking garage near Penn State on September 4th.

Part of the structure was a slab on grade with a retaining wall. That portion is still in place. The other part was framed as follows:

  • asphalt topping on

  • concrete-topping on

  • DOX plank floor system (essentially, a panelized prefabricated

  • assembly of concrete block with rebar grouted into voids near the tension face of the panel) framing between lines of steel girders, both cantilevered and drop-in spans, over
    steel columns

  • masonry shear walls at the perimeter


RE: How would you start this investigation?

Rich,
After the typical initial steps of background, construction, age, exposure, etc.  the most obvious approach would be to investigate corrosion...rebar and connections.

Structural overload is rarely an issue with parking garages that have been in place for a while.  Deterioration of members/components/connections would be the center of my attention, considering the time of year,lack of wind loading (unless you had a coincident storm event!), etc.

Ron

RE: How would you start this investigation?

Hello Rich,
I have recently begun my own investigation on an existing one story building.  I believe the roof structure is DOX Plank. I am in search for material specifications and detail information on DOX Plank.  Do you have any further information on this building system? Or know of a particular direction to take?
Thanks,
Jessica

RE: How would you start this investigation?

Hi Rich2001

As with any investigation I would start by checking with people in the area. (ie. security guards or locals) as to the weather and if they had witnessed or heard anything at the time.  For example this may lead to clues such as heavy rain resulting in large hydrostatic pressures from old, broken storm water lines.

I have found this initial approach helps greatly with respect to starting my calculations.

Regards

VOD

RE: How would you start this investigation?

If rainfall/precipitation is an issue.  The best data is from NOAA at http://www.ncdc.noaa.gov/oa/ncdc.html.  Costs just $10.00 per set.  Otherwise it's hearsay.  Also local newspapers almost always have archives on the Internet.  Make sure you get ALL of the construction, design, and maintenance records.  Check around for any photos or videos prior to the collapse, you'd be surprised how much can be out there.  Such pictures can help you determine the pre-incident conditions.  I assume you have the police photos and others taken immediately after.  Airphotos that are archived can also help with ponding water, general site conditions, etc.  Have fun!

RE: How would you start this investigation?

Does anyone have any design information regarding dox plank or can anyone refer me to a reference guide??

Thanks in advance,

Mozzo

RE: How would you start this investigation?

Mozzo,
  DOX plank was probably the first precast-prestressed plank manufactured in the (us).It appeared around the 1950's.
the planks were 16" wide,and were mostly 8"in depth.
It was a decent prefab concrete material(used in motels,and other reprtitive structures where cmu walls and steel framing occured.the biggest problem with it was the steel.
At that time steel was not at the proper or max strength yet.

this makes the product suitable only as a mild reinfoced product.Rich2001,when you get to the Dox part of your investigation look hard at the steel and pressure tha the design engineers intended for the deck.

RE: How would you start this investigation?

37ed

I have a similar problem with a 1950s structure.

Don't know any other way to consult with you except this reply.

Please talk to me within the guidelines of eng-tips.



RE: How would you start this investigation?

One good source book to help organize a forensic investigation is "Forensic Structural Engineering Handbook" by Robert T. Ratay. He has many good outlines and checklists for various aspects of an investigation as well as case studies to show how he has used the ideas presented. I recommend it as a good place to start!

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