The Origins and Use of Various Code Specifications and Design Guides for Concrete Slabs-on-Ground in Hangar Applications
Type of DegreeMaster's Thesis
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Research focused on the origins and applications of various code specifications and design guides used in the design of concrete slabs-on-ground in airplane hangar foundations. This thesis investigates the mathematical origins and theories used in the creation of design charts and nomographs from the American Concrete Institute, the Portland Cement Association, the Unified Facilities Criteria, and the Corps of Engineers. Consideration was also given to the use of built-in safety provisions such as load factors as well as designer-selected safety provisions in the design of slabs-on-ground. This thesis also describes the ideal approach to designing and analyzing slabs-on-ground in the application of hangar foundations. Results revealed that the best approach to designing and analyzing slabs-on-ground is dependent on the loading conditions and application of the slab. It was determined that the American Concrete Institute’s Committee 360 guide to design of slabs-on-ground is based on a number of different methods including the direct application of equations derived by Harold M. Westergaard, a pioneer in the field of plates on elastic foundations, as well as the use of the Portland Cement Association and Corps of Engineers methods for slab thickness selection. Furthermore, it was determined that the United States Department of Defense’s Unified Facilities Criteria method for slab thickness selection is based on the Corps of Engineers method, which is partially based on Westergaard’s equations for loads placed at the edge of slabs-on-ground. In addition, this research determined that the Portland Cement Association method for determining slab thickness is based on Westergaard’s equations for loads placed at the interior of slabs-on-ground. After determining the origins of the various code specifications and design guides, research was conducted to determine if any factors of safety are built into the design charts and nomographs within the codes and guides for selecting slab thickness. It was determined that there is no factor of safety built into the design chart used in the Portland Cement Association method, but that there is a factor of safety built into the design chart used in the Unified Facilities Criteria and Corps of Engineers methods.