Failure Paths and Safety Factors for Multiaxial Stress in Concrete

Abstract

Although mass concrete structures, such as dams are governed by multiaxial stress patterns, their safety is commonly evaluated in terms of a uniaxial safety measure. To assist such a structure's safety more realistically a multiaxial failure criterion and a relevant stress path to failure could be chosen in a reformulation of the safety measure. This paper compares the Mohr failure envelope with the principal stress failure envelope in terms of feasible paths, and their effect on the safety factor for a medium-strength concrete. Different values of the commonly defined safety factor are shown to be obtained for identical states of stress because of different assumptions for the initial stress state. To evaluate the safety of existing structures, the most likely failure path should be considered, and a distinction made between new and existing structures in the assumption of the initial state of stress.