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 Buoyancy load

  • ASCE Standards
  • ASCE7
Osama Mazaz's profile image
Osama Mazaz posted 01-17-2025 09:38 AM

Dear ASCE, I have a technical question regarding the buoyancy load ( uplift pressure from the ground water), as per ASCE 7 -22, section 2.3.4, could we consider it as Hw with factor of 1.0 , or the load will be under fluid load (F) with load factor of 1.2? could you please advice

Ronald Hamburger's profile image
Ronald Hamburger

Section 2.3.4 does not address buoyancy, but rather, self-straining effects, such as thermal loads, shrinkage, creep, etc.  In both ASCE 7-16 and 7-22 loads associated with water embodied in soil is considered as load H in the load combinations of Chapter 2.  ASCE 7-22 contains somewhat clarified language in this regard, relative to ASCE 7-16.  The strength load factors on hydrostatic load from saturated soils vary depending on whether the pressure is in concern with primary loads (e.g. lateral pressure against basement walls) or counter to primary loads (e.g. buoyant uplift).

Alex Thomas's profile image
Alex Thomas

Dear Osama , fluctuations in water table is affected to the structure may not be taken as a load in fact reduction of load can be applied. Due to attraction from above and gravity below to cause shrinking and expansion. In any case a basement floor is advisable. Weight of removed material is replaced with new loading. 

Alex Thomas BSc section B civil CEng FIE MASCE MICI MIGS PEng