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Abstract
A 3D, nonlinear finite element program NIKE3D is used in the Federal Aviation Administration's pavement design and response analysis of the rigid pavement structures. In 2000, an infinite element method was added to the NIKE3D program to simulate the infinitely deep subgrade. Using infinite elements efficiently can reduce the total number of elements, thereby saving the computational time. However, some computational results from the current infinite element formulation are questionable. Errors have been identified in the current mapping and shape functions of infinite elements. A new finite element formulation based on the improved mapping functions and shape functions has been developed and added to the NIKE3D program. The improved program allows meshing pavement foundation with traditional compatible elements, while using incompatible elements to the other layers with flexure deformations for more accurate analysis. In order to reduce geometric effects from meshing infinite elements, and errors arising from coupling of finite and infinite elements, a decay function is proposed and calibrated to the airport pavement application. The analytical results and other finite element programs, such as ABAQUS, are used for the comparison and verification of improvements.
Acknowledgements
The work described in this paper was supported by of the FAA Airport Technology R&D Branch, Dr Satish K. Agrawal, Manager. The contents of the paper reflect the views of the authors, who are responsible for the facts and accuracy of the data presented within. The contents do not necessarily reflect the official views and policies of the FAA. The paper does not constitute a standard, specification or regulation. We thank Jeffrey Gagnon, Dr Gordon Hayhoe and SRA International Inc., Chuck Teubert, Dr Edward Guo, Lia Ricalde and Dr Izydor Kawa of FAA Airport Technology R&D Branch.