Experimental investigation on strength and deformation of plain high-strength concrete under multiaxial stress state

To investigate the strength and deformation behavior of plain high-strength concrete(HSC)under multiaxial stress states,a large static-dynamic true triaxial machine was employed,and multiaxial tests were performed on 100 mm×100 mm×100 mm cubes concrete specimens.Friction-reducing pads were three-layer plastic membranes with glycerine in-between for the compressive loading plane.The tensile loading plane of concrete samples was processed by attrition machine,and then the samples were glued up with the loading plate with structural glue.Failure modes of specimens were described. The principal static compressive strengths,strains at the peak stress and stress-strain curves were measured,and the influence of stress ratios on them was analyzed as well. Experimental results show that the ratio of the compressive strength σ_(3f) over the uniaxial compressive strength f_c depends on brittleness-stiffness of concrete besides stress state and stress ratios. The formula of Kupfer-Gerstle' s and Ottosen's failure criterion for plain HSC under biaxial compression and multiaxial stress state is proposed respectively.