Proceedings of the 29th Annual Conference on Deep Foundations, 2004, Vancouver, British Columbia, Canada "Emerging Technologies", (DFI)
St. Joseph Hospital of Bellingham, Washington Addition Supported on Helical Pulldown Micropiles
J.L. Goen PE, C.M. Davis, R.A. Vickars
The Saint Joseph Hospital of Bellingham is located on a site underlain by glacial outwash. The construction of a five-story tower addition above an existing two story wing was supported by five large trusses that impose a 1600 kips (7117 kN) column load on five pile caps in the courtyard of the hospital and on the new pile caps inside the existing laboratory. The exterior columns of the trusses and the new parking garage addition were supported on conventional auger cast piles installed with conventional equipment. Helical PulldownŽ micropiles were selected for use in the courtyard and the MRI laboratory because lightweight installation equipment (maximum unit weight of 7.5 kips (33.3 kN)) had to be used and it was required that no spoils be produced. The installation equipment was lifted into the courtyard by the jobsite crane. Sixty Helical Pulldown Micropiles were installed for the pile caps in the courtyard. The pile caps inside the hospital were supported on 240 Helical Pulldown micropiles. Initial compression test indicated an allowable load for the micropiles to be 55 kips (244 kN). However, retest at a later date resulted in an increased allowed design load to be 85 kips (378kN) reducing the number of micropiles required by more than fifteen percent.
|article #1263; publication #68 (AM-2004)|