9802184 Panoskaltsis "Mechanics of Clays: Shear Banding and Anisotropy" The objective of this research is the development of a theoretical and computational framework which will constitute the basis for the complete characterization of the irrecoverable, path- dependent and anisotropic behavior of clays, including localization phenomenon. A general elastoplastic constitutive model will be developed. In particular, three aspects of this extremely complex behavior will be addressed. The first one concerns the modeling of the response of both normally consolidated and overconsolidated clays. For this purpose, the elastoplastic theory which will be employed is not the classical one but a new one, which is based on loading-unloading irreversibility and on a shift of the emphasis from the concept of yield surface to the concept of the elastic range. The new theory has the capability to describe both conventional and unconventional patterns of elastic-plastic behavior, in addition to being very attractive from a computational point of view. The second issue to be addresses deals with the modeling of the influence of soil anisotropy, both initial and stress induced, in the observed response. The last issue to be addressed is that of localization of deformation, the determination of the orientation and the width of the localized zone, as well as the associated mesh sensitivity. This is a very important issue, since crack initiation and propagation play a significant role in the serviceability and behavior of structures. ***
