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Title: Field evaluation of grillage foundation uplift capacity

Technical Report ·
OSTI ID:6621506
;  [1]
  1. Cornell Univ., Ithaca, NY (USA). Geotechnial Engineering Group

This study presents the results of eight full-scale field uplift tests on steel grillage foundations. The two field sites where the tests were conducted in New York State are described, along with the three grillage types found at these sites. Structural and construction details of the grillages are given. Soil characterization of the sites was conducted using a variety of in-situ test methods including the standard penetration, cone penetration, pressuremeter, borehole shear, drive cone, and dilatometer tests. Laboratory classification and strength tests also were performed to aid in the characterizations. The field testing equipment and the test procedures used for the uplift tests are described. The load-displacement results are given, as well as the ground movements in the zones above the grillages. The vertical shear model reported in EPRI EL-2870 is used to predict the uplift capacities, and comparisons are made with the field measurements. The vertical shear model, coupled with well-documented geotechnical properties, can be used to predict accurately the uplift capacity of grillage foundations. For grillages in granular soils, the incorporation of side shearing resistance is important. The field test results indicated that, for D/B ratios from 1 to 3, roughly 55 to 80 percent of the uplift capacity is attributable to side resistance, with only 20 to 45 percent of the capacity resulting from soil weight. This result is important when deciding on the allowable loadings that may be imposed from upgradings and increased tower heights. The use of existing foundations may result in substantial cost savings over new foundations, provided that adequate subsurface exploration and geotechnical data are incorporated into the planning and design stages. 63 refs., 224 figs., 82 tabs.

Research Organization:
Electric Power Research Inst., Palo Alto, CA (USA); Cornell Univ., Ithaca, NY (USA). Geotechnial Engineering Group
Sponsoring Organization:
EPRI
OSTI ID:
6621506
Report Number(s):
EPRI-EL-6965
Country of Publication:
United States
Language:
English