Return to index: [Subject] [Thread] [Date] [Author]

Re: Station Square Structural Failure

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Thor,

	The structural failure involving Station Square Shopping Center, in
Burnaby, B.C. took place shortly after the Hyatt Regency failure in
Kansas City.  One of the tenants was "Save on Foods", which, I
understand, is where the "action" took place.

	I have no knowledge of the events other than what was presented in an
engineering seminar presented in Calgary, and which I attended a year or
two after the failure.  The following  are my recollections of the
seminar; but I caution you; they may be incomplete or even inaccurate
after all these years.

	The structure consisted of concrete filled metal deck which was
supported on steel wide flange beams which passed over the top of steel
columns.  The roof was designed to accommodate car parking.

	The grand opening was so well received that, I understand, guards were
posted to keep the building occupancy down to the limit permitted by the
local fire bylaw.  At this time one column and one beam failed allowing
cars to fall into the produce department.  Fortunately, due to a number
of circumstances, there were no (or at least no serious) injuries.

	Following are a number of "circumstances" which had some bearing on the
failure.

1.)  The contractor accommodated structural deflections in the deck by
adding to the concrete topping to level the deck (also adding weight).

2.)  Sidewalks between rows of parked cars were widened without widening
the styrofoam filler underneath (also adding weight).

3.)  During the drafting process the critical beam size had been erased
(pencil work, not AutoCad) and a smaller size accidentally substituted.
As I understand it, this was detected after construction but the
decision was taken to accept the code violation rather than take
corrective action (I speculate that schedule played a role in this
decision).

4.)  One of the sub trades (sprinkler system, I think) drilled a hole in
the web of the critical beam to run his line through rather than run
around the beam.  This turned out to be a godsend because the early
stages of the failure broke the waterline spraying people with water and
warning them to flee for their lives.

5.)  There were no stiffeners in the web of the beam above the column.

6.)  There were no extensions of the bottom chords of the roof joists to
stabilize the columns.

	The initial failure mode was column buckling where the buckling action
took place within the web of the beam.  The bottom flange of the beam
displaced sideways by nearly the depth of the beam and changing the
configuration of the web into an S shape thereby effectively turning the
beam on its side and weakening it as well.  Somewhere about this time
the water line failed spraying water everywhere.  I don't recall the
order of the progression of the failure from this point.  I do, however,
recall that we were informed during the seminar that the metal roof
decking had acted as a catinary and held the cars out of the produce
department for four minutes thereby giving people time to escape.

	That is the best recollection I have of the seminar.  If anyone can
correct or add to what I've presented above I would be pleased to read
it.

	Following this our insurance underwriter wrote to us requesting that we
review all past projects to ensure that we had provided web stiffeners
or joist ties installed on all of our past projects.  Since this time
whenever I go into a warehouse type building I automatically check for
web stiffeners over the columns or for tie joists; I've actually found
this problem three or four times and had it corrected.

				Regards,

				H. Daryl Richardson

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********