This paper presents the results of cyclic axial load tests performed on reduced scale pipe piles at two study sites in sandy soils. In the last several years, offshore wind jacket structures have been introduced into the waters of the United States. Previous experience in developing jacket structures for the oil and gas industry in the Gulf of Mexico has allowed transition for use with offshore wind structures. Inherent differences in loading types and soil conditions are significant, with wind structures experiencing large cyclic overturning moments. Pile response to these high cyclic loadings, as well as aging effects, are critical to incorporate in the design process, and limited research exists on the implications of such. As part of an NGI Houston project funded by US Bureau of Ocean Energy Management, field testing of model piles using monotonic and cyclic loading has occurred at the University of Rhode Island (URI) and University of Texas at Austin (UT) to investigate the effects of these loading conditions. Lower than anticipated 7-day static capacities were observed at both sites. No capacity degradation due to post installation load cycles was observed at either site, while some gain in capacity was observed at both sites.
Timothy E. Keefe, Ahmed M. Hussien, Aaron S. Bradshaw, Andrew D. Deeks, James A. Schneider, Amir Rahim, Farnyuh Menq and Robert Gilbert
Keywords: pipe piles, jacket structure, offshore wind, cyclic loading, sand, aging
Publisher: DFI