Improvements to Modeling of Concrete Slab Curling by Using NIKE3D Finite Element Program

The NIKE3D three-dimensional finite element program is used by FAA for design and analysis of airport pavement thickness. This paper briefly describes research on improvements to the contact interface algorithm of NIKE3D and to the modeling of curling of concrete slabs. A modified algorithm to check the interface penetration has been developed and tested in the NIKE3D program. An example demonstrates that the improved program provides more accurate computational results. Both temperature and concrete shrinkage effects are considered in the modeling. In contrast to the traditional method of including shrinkage effects by changing material properties, a simple, innovative approach is used to predict approximate slab curling responses. A nonuniform distribution of the equivalent temperature gradient can effectively simulate the slab deflection under the combined environmental and wheel loads. Results from the improved NIKE3D program with the new method of modeling slab curling are compared with data from a full-scale slab test as well as with the commercial finite element program ABAQUS.