Volume 8, Issue 2 (June 1985)
A Direct Tensile Loading Apparatus Combined with a Cubical Test Cell for Testing Rocks and Concrete
A novel tensile loading apparatus is described, which when used in conjunction with an existing fluid-cushion cubical test cell, allows the simultaneous application of a pure principal tensile stress and transverse principal compressive stresses to concrete and rock specimens with a minimum of boundary constraints. A tensile stress is applied along one axis of a cubical specimen through brush platens glued to the specimen surface while compressive stresses are applied along the two remaining axes through fluid cushion systems. In this manner, three totally independent principal stresses can be applied with virtually no tangential surface tractions so that the actual stress state in the specimen is identical to the applied stresses. Stress-strain response curves and strength relations from biaxial tension-compression tests on Indiana limestone and steel-fiber reinforced concrete are presented as examples of the capabilities of the new device.