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Recent content by MIBridgeEng

  1. MIBridgeEng

    Concrete Cantilevered Retaining Wall - LRFD Moment at Heel

    In the transportation industry, we are governed by the AASHTO LRFD Bridge Design Specifications. It requires factored loads for the overturning, bearing pressures and sliding. You would then check the heel bending using the factored loads of the soil above the heel and the resultant factored...
  2. MIBridgeEng

    LRFD Gravity Wall Design

    Yes, I've found that sliding is a huge issue with LRFD. The deadload of the wall (which helps create friction) has a small load factor (like 0.9), but the horizontal earth presures have a pretty high load factor like 1.5. It creates a "perfect storm". I've had better luck with spreadfooting...
  3. MIBridgeEng

    AASHTO Interim Blue Pages

    Our office just recieved some interim updates to the AASHTO Manual for Condition Evaluation and the AASHTO Guide Specifications for LRFD Seismic Bridge Design. Historically interims have contained "replacement" pages to show the revised portions of the code. These most recent interims, to...
  4. MIBridgeEng

    Rankine versus Coulomb Earth Pressures

    AASHTO LRFD seems to flip flop in their cantilever retaining wall figures (Section 3 and 11) showing the inclination of the resultand active pressure to be at angle beta (parallel to backfill slope) or at angle delta (wall friction). This confuses me a bit. I've also seen several figures...
  5. MIBridgeEng

    Traffic barrier on MSE Wall

    Check out AASHTO LRFD Article 11.10.10.2. It specifically tells you to design for 2 kips/ft, not the 54 kips bridge barriers are designed for. Also, I do recall seeing a recent paper on the internet regarding this specific issue. I don't have it right now, otherwise I'd attach it.
  6. MIBridgeEng

    retaining wall with keys

    I don't design in California, but sections 5.6.3, 5.6.4.1, and 5.6.4.2 in the Caltrans 2003 Bridge Design Specifications does talk about keys and when to apply active and passive pressures to the key...
  7. MIBridgeEng

    Spread footing abutment question

    Maybe your've already done this, but also the check the case where the wall is built and backfilled without loads from the superstructure. This could be the case during construction (i.e. building the abutment fully prior to setting the beams) or during a future rehabilitation (i.e...

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