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  1. TTK

    Track Clearances at Passenger Platforms

    I was provided with a sample track clearance diagram for an urban transit authority. The project that I am working on does not necessarily have to follow these clearances, but I don't want to deviate from them unless absolutely necessary. One of the clearance dimensions is a distance from the...
  2. TTK

    Bridge "Rehab" vs. "Retrofit"

    Although definitions can vary from region to region, Qshake provided what I would consider to be the best definition of these terms.
  3. TTK

    Historic Alloy Steel Properties

    Thank you Pressed! That's exactly what I was looking for...may I ask where you found it? If your source is prior to 1917, then all copyrights have expired and it's now in the public domain. If your source is newer than 1917, there is a chance that copyrights still apply. You provided the...
  4. TTK

    Historic Alloy Steel Properties

    Thanks for all of the replies everyone. Just to clarify, it has always been my intent to sample and test the steel (strength, hardness & chemical composition on several samples), but I would also like to have the original ASTM standard to compare the test results against. I have an e-mail...
  5. TTK

    Historic Alloy Steel Properties

    I now know the material was first used in 1915, but the first ASTM specification for it was not created until 1925. ASTM A94-25T "Tentatiave Specifications for Structural Silicon Steel" Fy(min) = 45 ksi Fu = 80 to 95 ksi Carbon (0.44% max) The specification was withdrawn by ASTM in 1963...
  6. TTK

    Historic Alloy Steel Properties

    JoeTank, Thanks for the reply. Silicon Steel was used sparingly in major bridges during the 1920's and 30's. I have read that the steel mills did not market the material because their preference was to keep everyone using the carbon steels (why I do not know). The silicon steel...
  7. TTK

    Historic Alloy Steel Properties

    Hello, I am trying to identify the chemical and strength properties of high strength silicon steel used in the 1920's and 1930's. More specifically, the steel would have been used in bridge construction and it would have likely been the highest strength steel being used in this industry at...
  8. TTK

    AASHTO Bridge 16th and 17th edition differences

    The 17th Edition is really just the 16th Edition with all of the interim updates included. AASHTO wanted to publish one last "clean" version of Standard Specifications before they archived it and moved on to the LRFD Specifications as the new standard. If you have most/all of the interims for...
  9. TTK

    LRFD C6.10.3.4-1

    The L/85 criteria would usually only apply for I-girders, and your steel box (with internal cross frames) should more than satisfy this criteria. Be very careful with this criteria for I-girders though. Many DOT's require contractors to submit specialized erection plans ($$$) for sections...
  10. TTK

    lever rule for DF for interior girders, 2+ lanes

    The AASHTO Standard Specifications for Bridges (STD) suggests WHEEL LOAD distribution factors of S/4.0 and S/5.0 depending on the thickness of the non-composite steel grid deck. These distribution factors are for moments in interior beams for bridges with two or more design lanes. The AASHTO...
  11. TTK

    lever rule for DF for interior girders, 2+ lanes

    When using the lever rule for interior girders, hinges are assumed to exist in the deck at each girder and simple span distribution is used for each wheel load. For a 5 ft girder spacing, two lanes loaded and a truck with 6' transverse wheel spacing, the worst case loading with the lever rule...
  12. TTK

    Tie Rod Connection at Crown of Adjacent Box Beams

    The OhioDOT detail would seem to work for Tie Rods or PT strands but seems like a hassle for normal width bridges. All of the designs I have done have used 7-wire strand for the transverse PT and the strand simply follows the crown of the roadway across the bridge. That is a very wide bridge...
  13. TTK

    Bridge Deck Pouring Sequence

    Sorry of the typos...I need to learn to take more time to proof before hitting submit!
  14. TTK

    Bridge Deck Pouring Sequence

    Hmmm...this could be an interesting discussion on a couple of different levels. One perspective is the contractor bid the work knowing full well that construction joints would be required in the deck at the integral pier bents. If the owner feels that construction joints will provide better...
  15. TTK

    Post for Hip Roof

    I could see a situation where a VERY small hip roof would not require a post to support the ridge beam. An example might be a small roof with low design loads that produces very little thrust. "System effects" or "diaphragm action" are also popular explanations of why some existing hips...
  16. TTK

    1900 Bridge Design

    How do you know the age? Is it on the local or national historic register? If so, the application forms may have information on the designer and possibly the design specification used.
  17. TTK

    1900 Bridge Design

    What type of bridge is it? If it is a metal truss and you can identify the manufacturer by a plaque on the bridge or other historical documents then you may be able to determine their standard design loading. For example, almost all of the lenticluar truss bridges were designed and built by...
  18. TTK

    Top Plate & Trusses

    What is the application? Is this a lightly loaded residential roof truss or a heavy commercial truss? What is the truss spacing and stud spacing? Residential trusses at 24" o.c. don't always line up with studs at 16" o.c., and that's what the double top plate is for. I'm guessing this must...
  19. TTK

    Guard Rail Strong or Weak Posts

    try to get your hands on a copy of the AASHTO Roadside Design Guide, this has a complete discussion of guardrail systems. weak posts are extrememly small and their only purpose is to hold the rail element up at the proper elevation to re-direct traffic upon impact. The posts will easily shear...
  20. TTK

    Excel Engineering Spreadsheet Applications

    Ok, I think I found a fairly easy solution without getting into VBA programming but it would mean reorganizing your data. If you eliminated the second column of data (section size) and instead made these sizes column headings you will have a true array with the Fb values being the raw data in...

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