LIMIT ANALYSIS THEOREMS FOR IMPLICIT STANDARD MATERIALS - APPLICATIONTO THE UNILATERAL CONTACT WITH DRY FRICTION AND THE NONASSOCIATED FLOW RULES IN SOILS AND ROCKS

A new class of materials called Implicit Standard Materials was propos ed in a previous work. It allows one to generalize Fenchel's inequalit y and then to recover dow rule normality for non-standard behaviours, in particular for soils and unilateral contact with dry friction. In t his work an extension of the limit analysis theorems to this news clas s of materials is presented. Some relevant features are pointed out, s uch as non-uniqueness of the limit load and coupling of the lower and upper bound problems. Some analytical and numerical solutions are pres ented to illustrate the theory. (C) 1997 Elsevier Science Ltd.