Mechanical behavior and failure criterion of the gangue-based haydite concrete under triaxial loading

Abstract

Triaxial loading tests were carried out on the gangue-based haydite concrete cube specimens (100 × 100 × 100 mm³) and plate specimens (100 × 100 × 50 mm³) to investigate the mechanical behavior of this kind of lightweight aggregate concrete (LWAC) under multi-axial stress state, and accordingly to develop the failure criterion for the finite element analysis of LWAC structures. Experimental results revealed that, under triaxial compression loading, most of the haydites within the specimen were crushed when the stress ratios σ _1/ σ ₃ ≥ 0.3 and σ _2/ σ ₃ ≥ 0.5. The gangue haydite concrete exhibited “plastic flow plateau” at this stage, which was conservatively regarded as the ultimate strength of the LWAC under triaxial compressive stress state. As a result, the tensile and compressive meridians on failure envelope surface are intersected with hydrostatic axial at two points, completely different from the characteristics of normal weight concrete for which the failure surface is unclosed and open-ended under compression. In terms of the test data, a four-parameter triaxial failure criterion for LWAC was developed. The strength envelope in the deviatoric plane adopted elliptic curve similar to that of Willam–Warnke model, and the tensile and compressive meridians were represented by quadratic functions with four parameters. Two alternative methods, i.e. the characteristic strength points method and the least square regression method, were used to determine the model parameters. After compared with the failure criterion recommended by fib Model Code 2010, methods proposed in this study are preferred especially when the plastic flow property is taken into account.