About me: Technorati Profile
310 Mesnard Street
Hancock, Michigan 49930
(906) 482-5202
billkallman@charter.net
Born - February 18, 1937 Brooklyn, New York
Marital Status - Married - Mary Richards-Kallman
Children - Margaret, Holly, David, Regina, Nancy, Carol, Arlene, Elizabeth, David, Charlotte, Rebeccah and Fiona
Who I'd like to meet: I 35W over Mississippi River Bridge 9340
August 15, 2007
Bill Kallman, PE
Investigation of Collapse by Kallman Engineering
On August 1, 2007 at 6:05 pm the subject bridge completely collapsed, from
abutment to abutment. The bridge consists of approach spans consisting of
stringers, and a 3-span deck truss over the river. Completed in 1967, this
bridge has had major repairs since then, and in-depth inspections since 1997.
Two engineering reports, one by University of Minnesota Civil Engineering
Department in 2001, and the other by the URS Corporation in 2006 attempted to
explain faults discovered in the field inspections made by Mn-Dot for over 30
years. The complete file is found on the Mn-Dot website
http://www.dot.state.mn.us/i35wbridge/history.html and we have read all of this
material and visited the actual bridge site in Minneapolis.
We conclude that the approach pavements on-grade shoved the bridge during the
replacement of the transverse joints on the trussed section, hard enough to
destabilize the upper chord members, detach the deck, and drop the center span
at the points of contraflexure. Less than a second later all the other spans
fell towards the river.
The very warm weather preceding August 1, 2007 and the deck joint removal
defined the timing of the collapse. The "frozen" bearings, cracked and
misaligned approach span members, early deck repairs, the tilted north pier,
distressed condition of the on-grade highway pavement joints leading to the
bridge, all point to severe pavement shove as the cause of collapse.
Quite often, and erroneously so, the phenomena of joint widening in P.C.
concrete pavement is associated with traffic loads, age, and water infiltration.
NOT SO. As the concrete slabs expand and contract with temperature change,
sub-grade material forced up into the joints ejects the joint filler and
gradually widens the joint. This causes a general movement of the pavement
slabs (downhill usually), often relieving the pressure by "blowing up" at a
joint during hot weather. An asphalt repair is then made by a highway
maintenance crew to be permanently replaced by concrete at a later date, which
in turn increases the shove forces.
Any bridge in the way of this pressure will have its bearings displaced. Later
the abutment backwalls are sheared off at the bridge seats, decks rotated, and
other signs of distress appear.
During my 35-year career with the New York State DOT, a pavement detail was
implemented prior to the 1964 Worlds Fair in Queens, NY, where a 5-foot
expansion joint was introduced into the at-grade concrete pavement. This joint
was ordinarily asphalt on the sub-grade and served well, but required removal
the resultant "bump", annually. I recall later lengthening it to 25 feet for
ease of construction and maintenance. These joints were called Stress Relief
Joints. I know of no experimental work on this phenomena, however measurements
of compression within pavement slabs have approached 8,000 p.s.i.. I believe
this pavement shove affects many, if not most, bridges and should be eliminated
by appropriate details in highway pavement design.
With great respect for the responsibility to our clients – the highway travelers
– who in this case have been killed by our ignorance, I consider it our duty to
inform the public of the cause of the collapse, our regret for the lives lost,
and our program to see that this doesn't happen again.
Bill Kallman
Structural Engineer
310 Mesnard Street
Hancock, MI 49930
Phone: (906) 482-5202
Fax: (906) 482-5202 (call first)
E-mail: billkallman@charter.net
CT 16546 MI 41074 NY 40760
Have you heard about our solution to Global Warming?
In addition to eliminating half of all greenhouse gases by replacing coal-fired electricity plants, the use of a Solar Roadway system will easily allow the return of an all-electric car, since it can be recharged by the road itself. Electricity generated by the road and vehicles recharged by the road. No more fossil fuels at all (except for lubricant, which can be synthesized).
Global warming solved, wildlife protected, dependency upon foreign oil eliminated, & terrorism bankrupt.
Just think about it...
If you wouldn't mind, we'd love for you to go to our website and sign our Encouragement List. You could help us to save our environment one road at a time. We’ll give you a free link back to your MySpace page or website!
If you’d like to support our solution, then please – sign our Encouragement List and place the Solar Roadways in your Top Friends List.
