House on Piles
Structural Engineering for a House Built on a Pile and Grade Beam Foundation System
As lots to build homes on within the urban growth boundary in the City of Portland become scarce, locations that were once thought to be impossible to build on are being developed. This lot had on Mt. Tabor with incredible views large amounts of fill has been dumped on it over the years as other houses in the surrounding area were developed.
This structure is supported by approximately sixty pin-piles driven through fill as deep as twenty feet. Because the soil that was deposited over the past twenty or thirty years can not support any weight from the building, a concrete beam and steel column system was designed to span from pile to pile and follow the grade of the slope down the hill.
This project required close coordination of the several people: the general contractor, the pile driving contractor, the foundation contractor, the geotechnical engineer and Ogren Engineering - the structural engineer - just to get started. In addition, the building department's engineers were initially skeptical a structure could be built on this site; through a series of meetings and presentations Ogren Engineering was able to successfully negotiate a structural system which satisfied the skepticism of the lead structural and geotechnical engineers in the City of Portland building department.
As complex as this project was to design, the plans and construction documents generated by Ogren Engineering were complete and through enough that not a single RFI was generated during the installation of the piles or the construction of the foundation. These clear and complete plans saved the owner time and money building their home.