Foundation Support of a Tank

SUMMARY
A flat bottom 60 foot diameter, 60 foot tall, liquid nitrogen storage tank is supported on a pile foundation at 15' above grade. Pile foundation and pedestal structure to support:
Life of the structure is 30 years. Planar tilt is limited to 1/2" in 60' during the life of the structure. Out-of-plane, differential settlement is limited to 1/8" in 30' and 1/4" in 60' during the life of the structure. Settlements will govern this design as much or more than seismic and wind forces.

DESIGN LOADS  for FRAME ANALYSIS PROGRAM
This frame is an elastic ordinary moment resiting frame.  The design is for elastic response only and does not use yielding of any member for energy absorbtion. The value of R for ordinary moment resisting frames is the same as the R for elevated tanks on unbraced legs.

EXTEND PILING THROUGH PILE CAP to DECK
Piling below the pile cap is considered to be buoyant. Top of piling fixed within pile cap.Spring restraint to resemble soil lateral resistance applied at soil/pile cap interface. Concrete and rebar cage top 25' of pile. The deck is designed as a two-way slab supported by 21 columns.For this analysis,  S-Frame 3D finite analysis program was used to calculate moments, axial loads, and deflections along the midline of the structure.

LOADS to DECK MID-LINE
Design for the '97 UBC ultimate strength of columns. Spring values at grade are given an arbitrary factor of 1.0.

Calculation Reference

Pile Foundation

Pile Design UBC

Pile Design ASCE