For those of you who are interested in bridges , the Minnesota DOT has
just announced that the gusset plates in the Blatnik Bridge (on
I-535/HW53) has gusset plate problems , which from what they have said ,
to me, appears to be "edge buckling" problem. This is similar to what
was photographed in 2003 to have occurred in I-35W bridge (collapsed on
August 1, in 2007 resulting in 13 deaths and more than 100 injuries)
and recently in DeSoto Bridge (closed for demolition and replacement)
without any injury. The Blatnik bridge is a 1961 steel truss arch
bridge about 8000 feet total length. MN DOT is planning to close
certain lanes and repair/retrofit the gusset plates by adding angle
stiffeners to the free edge of gusset plates.
You might wonder what s going on in Minnesota and why all these steel
truss bridges are having gusset plate problems. Well, being a little bit
familiar with gusset plates and steel truss bridges, this is a
nation-wide problem and most likely the reason Minnesota DOT is finding
out about these problems is that they are looking at their gussets!
Also, having worked on I-35W and the DeSoto bridge since last year, I
feel that adding an inch or two of additional resurfacing concrete (
which was done in both cases) is not a good idea unless you check the
stresses and find out that even with that additional dead load , the
AASHTO factors of Safety are in place.
Sincerely
Abolhassan Astaneh-Asl, Ph.D., P.E., Professor and
Consultant on Structural and Earthquake Engineering and Protection of
Buildings and Bridges against Blast and Impact
=====================================
******* ****** ******* ******** ******* ******* ******* ***
* 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@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
******* ****** ****** ****** ******* ****** ****** ********