Browsing by Subject "Foundations"
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Item Performance of pile foundations for fixed-type platforms during Hurricane Katrina(2007-08) Lee, Yonghoon, 1977-; Gilbert, Robert B. (Robert Bruce), 1965-According to increasing demand for oil, numerous offshore oil producing structures have been constructed in the Gulf of Mexico. A jacket-type platform is one of the oil producing structures, which has deck structures, jacket frames and foundation structures. For foundation structures, driven steel pipe piles are typically used. From Hurricane Katrina, no known collapses of offshore oil jacket platforms occurred because of foundation failure even though foundations were subjected to environmental loads greater than their design capacity. Conservatism in pile design significantly impacts on the cost of the jacket platforms. This research intends to study the bias between the predicted and the observed capacity of pile foundations. To investigate the bias, a plastic model of pile system collapse is adapted and extended. The model is useful to account for an interaction between axial and lateral capacities of individual piles and also to consider interactions between multiple piles. Analyses of foundation capacity for 8-leg and 6-leg jacket platforms using the plastic model result in an interaction collapse diagram for the foundation. Compared with the loads from Katrina the plastic model indicates that the pile systems should have collapsed under the loads. Finally, sensitivity studies regarding pile geometry, loading, soil properties and pile-soil interaction are conducted to identify and study the potential sources of bias in the pile design. The potential sources of the bias include (1) uncertainty from soil sampling and field/lab testing, (2) the contributions of mudline elements to vertical resistance of pile system, (3) rate of loading, (4) reverse end bearing, (5) hardening of sands at pile tips and (6) set-up effect. When the effects of these potential sources are considered to increase axial and lateral capacity of individual piles, the interaction diagram for the two example platforms expands beyond the estimated environmental loads from Hurricane Katrina and therefore the survival of the two platforms from the hurricane may be explained.Item Why give to K-12 education : understanding the perspectives, approaches, and desired outcomes of foundations(2017-05) Cox, Lindsay Danielle; Holme, Jennifer Jellison; Treisman, Uri; Jabbar, Huriya; Reyes, Pedro; Gooden, MarkPhilanthropy has a long history in the American public school system, but a marked influx of private dollars and a shift towards strategic giving has drawn increased attention. Prior research has explored funding patterns, strategies used by foundations to leverage their grants dollars, and the emergence of venture philanthropy; yet little has been done to understand the perspectives of the foundations, the philanthropic approaches that guide their giving, and the desired outcomes of their involvement in K-12 education giving. Using a multimethod qualitative design, this study aims to fill this void through a line of inquiry focused on the perspectives of the leading foundations and how they differ from one another in K-12 education giving. This study reviewed the 35 largest United States based K-12 education foundations by total annual giving in 2013 in two stages. Stage One of the study analyzed annual reports, mission statements, foundation portfolios, and online foundation websites to grasp the degree of adherence to venture philanthropic tenets and how foundations differ in their approach and perspectives in education philanthropy. Stage Two then sought to capture the perspectives of foundation representatives through interviews to better understand why foundations choose to give to education, the philanthropic approach of their giving practices, and the desired outcomes from their work in K-12 education. In the study, I found patterns of similarities and differences in foundations’ perspectives, approaches, and desired outcomes by their degree of adherence to venture philanthropy. Further, I illustrated how some moderate to high venture philanthropy foundations are acting as policy entrepreneurs.