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ASD load combination (uplift case) and overturning factor

  • 1.  ASD load combination (uplift case) and overturning factor

    Posted 12-24-2019 08:49 AM
    Dear Members,

    For the following load combination in ASCE7-05, what should be the overturning and sliding factor (wind or seismic) to be considered in the foundation design.

    0.6D + W + H
    0.6D + 0.7E + H

    It is understood that 0.6D+W combination assumes a 10% over-estimate in gravity load (0.9D) and then a 1.5 safety factor to bring the number to 0.6D+W. A safety factor of 1.5 is already considered to be present in-built. So, it would be ideal to use 1.0 safety factor for both overturning and sliding case (Wind or Seismic) when the above combinations are used in design.  PIP structural design criteria (PIP STC01015) is also in line with this approach.

    The actual problem is nowhere I can see this explained in ASCE7-05. Request members to share their thoughts and references in this regard.

    Best regards,

    Ratheesh Kuppusamy M.ASCE
    Abu Dhabi, UAE