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  1. SteelMover

    Built-up section - Steel Spreader Beam

    With all of the above concerns by the time you get your beam design modified to your satisfaction, you could have specified an entirely new beam and put the money into material instead of design. I usually keep the designs as simple as possible and use an omega of 5-6 depending on the failure...
  2. SteelMover

    What kind of truss is this?

    A concrete example is attached. Palazetto Dello Sport in Italy completed in the late 50's. Phenominal structure!http://files.engineering.com/getfile.aspx?folder=a6af6ef3-d788-4781-ad3e-762fec8c1a28&file=379487497_b0bd7be023.jpg
  3. SteelMover

    Crazy handshakes

    My anecdote: I am great at concentrating and I actually get very distracted by handshakes. It is typical for people to give you their name just before or while shaking your hand and my concentration on the act of the handshake almost always makes what I hear (the name) never enter my...
  4. SteelMover

    Bolt inspection, vibratory conditions

    I have a pretensioned bolted connection that always sees a rather high level of vibration where I want to use loctite thread locker to prevent bolt rotation, not safety wire. Does anyone have a clever & durable way of marking the bolts for inspection to determine whether or not there has been...
  5. SteelMover

    Bridge Collapse in MN

    Evaluation of this bridge collapse should include bridge experts, the inspection team, as well as material experts, fatigue experts, those with knowledge of long-span truss design, geotech & foundations. A diverse team such as that can avoid tunnel vision you get when you have a very...
  6. SteelMover

    35W Failure Investigation

    I would maintain that we learn....maybe codify...more from 1 bridge that fails than 1000 that stand for their whole life.
  7. SteelMover

    Bridge Collapse in MN

    And deteriorates infrastructure
  8. SteelMover

    Bridge Collapse in MN

    Prost - How about repealing the tax decrease for the wealthiest Americans? When much of our infrastructure was built, dams, interstates, etc. 30s to 60s the top tax bracket ranged from 62% - 92%. Now its political
  9. SteelMover

    Bridge Collapse in MN

    The problem with these technologies is LAWYERS. We actually tried to do this with stadiums, but we were cut off because there was too much liability involved. Your entire organization would be hung unless legislation was passed that barred the possibility of lawsuits against engineers as long...
  10. SteelMover

    Bridge Collapse in MN

    Mtnengr - For a good example of crack propagation due to material temperature see the Hoan Bridge failure in Milwaukee. It was really cold when that happened. Three girders had fatigue cracks propagate clean through. Though it didn't fall due to catenary action in the deck. It is believed temps...
  11. SteelMover

    Bridge Collapse in MN

    Dr. Dexter's 2001 report summary: Bridge 9340 is a deck truss with steel multi-girder approach spans built in 1967 across the Mississippi River just east of downtown Minneapolis. The approach spans have exhibited several fatigue problems; primarily due to unanticipated out-of-plane distortion...
  12. SteelMover

    Bridge Collapse in MN

    Some of the commentary about the event on news programs has been incorrect. The photo shown above by BIMR is of the south end of the bridge. Locks are on the south side of the river here, train tracks are on the north side. The video footage looks like it was taken from a camera that looks at...
  13. SteelMover

    Bridge Collapse in MN

    See below http://en.wikipedia.org/wiki/I-35W_Bridge It doesn't look like a true cantilevered back span, though I'm not a brige guy
  14. SteelMover

    Bridge Collapse in MN

    Additionally, the visible failure or the north side of the main span seems to progress as shear failure at the within the truss at the north abutment, but the south side seems to already be moving, and ahead of the north side. It is plausble that the failure mode seen at the visible abutment...
  15. SteelMover

    Bridge Collapse in MN

    I was down there yesterday just after it happened and it was surreal to see that there was just no bridge there where there used to be one. Unfortunately someone with our knowledge couldn't help much as it was a complete collapse. From watching the video I see an almost perfectly symmetrical...
  16. SteelMover

    A325 vs A490 Bolts used as a pin.

    Just about any machine shop can do pins with a wide range of steels. I would bet you are within 10 miles of multiple shops that will do this. We typically spec AISI 1018, 1045, 4140, 4150, 8620; all readily available in bar stock. Check a Ryerson catalog for material properties & availability...
  17. SteelMover

    Column Failure

    The crack direction is paramount to the fix. Concrete is beautiful in that it describes to you exactly its stress state when it cracks. Your principle tension is perpendicular to that crack, and from what it sounds like it must be angled 60 degrees or more from the plane of the slab. That being...
  18. SteelMover

    Anchor Bolt Tension in BP subject to Moment

    AISC Design Guide 1
  19. SteelMover

    A325 vs A490 Bolts used as a pin.

    HGTX, RARSWC- Even if A325 and A 490 bolts had the same fracture toughness, (which I don't have time to research) you have a lower saftey factor against fracture failure by the Griffith equation if you are applying a higher stress to the A490 than say the A307. You will genearlly be stressing...
  20. SteelMover

    Timber Frame Houses

    From what I understand its fairly specialized. I know these guys know what they're doing: http://www.nehilsivak.com/ It's a passion of Tom's, one of their principles. Maybe they could perform some design review for your first few attempts until your get your feet wet.

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