Stress-Strain Mechanism of Expanded Polystyrene Foam under Cyclic Loading Conditions within and Beyond Yield States

Abstract

This paper attempts to describe deformation characteristics of EPS geofoam under cyclic loading conditions within and beyond yield states. The loading pattern on geofoam specimen represented a construction sequence as well as a traffic loading of the bridge approach structure. A large size of EPS block specimens with dimensions of 30 cm high, 30 cm wide and 60 cm long were tested in laboratory with different cyclic loads pattern and wide range densities. From testing results, increase in density of EPS geofoam, yield state as well as overall deformation characteristics of EPS foam decreases. The permanent deformation was significantly observed on a low density of EPS geofoam with a low yield state. A stiffness of EPS significantly decreased with increasing of stress level beyond yield stress of material. The stress-strain mechanism of EPS was hardening without failure behaviors when the stress level being more than its yield stress. The overall cyclic behaviors of EPS can be successfully characterized with its yield state.