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  1. civilperson

    Bridge Design Consulting Fees

    Try $65/sq ft for first estimate and use Standard Plans from AASHTO and the DOT for details and examples. Any changes from these assumptions will require a higher fee.
  2. civilperson

    column under designed, what now?

    Wrapping the column with either high modulus fabric, (with epoxy matrix) or steel is a normal method of retrofitting for seismic requirements. This may work for you if bending is the critical fail mechanism.
  3. civilperson

    Pipe Zone Material

    If the design optimum moisture is held in the native soil and the compaction of the bedding/spring line is uniform and meets compaction requirements then the pipe will utilize the available wall strength. The backfill is equally important with thin lifts compacted at optimum moisture content...
  4. civilperson

    cast in situ concrete piles

    If the holes are excavated immediately prior to concrete placement then a minimum strength of 80% of F'c is recommended before disturbing the adjacent soil. Using high early mix designs, this can be less than 24 hours.
  5. civilperson

    Omitting Base Plate Grout

    High moment foundations such as light poles do not use grout, but bear on leveling nuts. Grout is unnecessary when the bolts/plates are correctly designed to accept the load.
  6. civilperson

    6000 psi in 12 HOURS!

    A heated form for the concrete mix can get you 50-75% of the ultimate strength in the first 18 hours. Try a 8400 psi or better design mix warmed to 160 degree max(f) at 20 degree/hour increase from the initial set temperature.
  7. civilperson

    Cantilevered Slab Deflection

    The stiffest dimension will determine the deflection. Given equal load/area, the 7' cantilever deflection will govern.
  8. civilperson

    Question about pitch of underground drainage pipe

    Water will flow in a flat pipe, (or ditch). Minimum pitch is required for velocity requirements.
  9. civilperson

    AASHTO SHEAR CONNECTORS

    AASHTO worries about fatigue.
  10. civilperson

    How to prevent another leaning tower of pisa

    Calculate the horizontal forces on the structure, (wind, waves, seismic), and apply to the proposed foundation. The 1000 pound per square foot design may not match a saturated subgrade, (a better than 90% chance that the soil is sufficient), but expansive or collapsing soils should be checked...
  11. civilperson

    expansion couplings in above grade pipe

    Expansion joints are unnecessary. Either the water will maintain a close temperature or the steel will be stressed within the allowable limits for changes of temperature.
  12. civilperson

    Bi-Axial Bending + Tension

    The net compression due to bending will be reduced from the uniform tension. A conservative method would ignore this lessening for the compression side. The tension would have to be permanent and unchanging to use the lesser compression.
  13. civilperson

    Permit Vehicle Braking Load

    Change of speed is not "speed". This is acceleration and it is proportional to force,(or friction).
  14. civilperson

    Permit Vehicle Braking Load

    Speed will NOT effect the "braking load", the coefficient of friction between the tires /pavement is the limiting case for locking the brakes and causing horizontal load.
  15. civilperson

    Wind farm job on 100m fill?

    Cast in place drilled piles/caissons will work if the horizontal subgrade modulus can be determined. Wind foundations are moment controlled, (a vertical beam with horizontal load).
  16. civilperson

    Doubling RC Lintels

    Add only, no composite action with mortar.
  17. civilperson

    6x6 welded wire mesh as "chairs"

    Steel resting on the surface before topping is the surest method of knowing the vertical location for that steel. A low/medium frequency compressed air driven vibrator made out of a series of closely spaced pipes will assure good consolidation when used on leveled/placed mix. A chair would be...
  18. civilperson

    Existing Soil Foundation

    Why do you need a concrete foundation?
  19. civilperson

    Jib Crane Foundation

    The maximum moment from the jib crane can be resisted by the caisson depending on the horizontal soil modulus and the depth. I would model the caisson as a rigid structure with a pivot location approximately a third up from the bottom of the caisson. This is usually the most economical design...
  20. civilperson

    Building Expansion joints in Middle East

    Air conditioned buildings experience very little temperature change in the structural steel inside the cladding.

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