Coupled Hydraulic System for Tensile Testing in Compression-only Machines

Abstract

Fracture theory for normal strength concrete has thoroughly been studied over the past decades. Through indirect and direct tensile testing techniques, the postpeak softening response of conventional concrete has been established and utilized in analysis and design. However, for more recently developed concrete materials (e.g. fiber reinforced, high performance) under complex loading conditions, the required fracture properties to predict response are extremely limited. Considering this lack of knowledge, the objective of this research was to develop a uni-axial tensile testing technique to attain the post-peak softening response for ultra-high performance concrete for ultimate use in conjunction with an applied confining pressure system. Specifically, this research was conducted for implementation into an existing, large compression-only machine at the US Army Engineer Research and Development Center (ERDC). The new methodology enabled the existing testing frame to apply a stiffening force, while an external hydraulic plunger cylinder performed the tensile test. The scheme enables tensile testing under confining pressures in the compression-only machine.

Combining Thermal Loading System with Acoustic Emission Technology to Acquire the Complete Stress-Deformation Response of Plain Concrete in Direct Tension

“…Since Evans and Marathe [ 12 ] observed the softening response of plain concrete in a DTT and obtained the corresponding complete tensile stress-strain curve, there has been an outpouring of literature focused on the tensile properties of various concrete materials [ 2 , 13 ], the effects of different test methods [ 3 , 4 , 5 , 14 , 15 , 16 ] and the simulations of the fracture process [ 17 , 18 , 19 ]. Generally, the DTTs are conducted on a tensile test machine (TTM) with high stiffness [ 3 , 14 ], or a special electronic servo-controlled TTM with a fast response time [ 4 , 20 , 21 ].…”