Numerical modeling of RC slabs on tensionless elastic subgrade

The problem of slabs resting on elastic soil is tackled by means of developing two non-linear finite element programs, WINKLER and PSEUDO-3D. The program WINKLER is based on the classical Winkler hypothesis whereas a three dimensional elastic analysis is used in PSEUDO-3D. A tensionless behavior is considered for the subgrade, by assuming that the subgrade reacts only in compression. The existence of sinkholes/cavities underneath the slab is also modeled. The size effect and the location effect of such sinkholes on the behavior of reinforced concrete slabs are studied. A new concept of variable subgrade modulus values for a subgrade is introduced in the PSEUDO-3D model. The new model Pseudo-3D is compared and contrasted with the classical Winkler hypothesis. Contours of subgrade modulus as well as dimensionless equivalent subgrade modulus, for slabs on weak, intermediate, and stiff soils are presented.