Tension softening curves of plain concrete

•We examine the fracturing phenomena of concrete using the ESPI technique.•The length and width of fracture process zone in concrete were quantified.•Tension softening curves (TSCs) of concrete were evaluated.•The estimated TSC were approximated by bilinear and exponential curves.•TSC were expressed as a function of cube compressive strength of concrete.

The tension softening curves (TSCs) of plain concrete with compressive strengths varying between 40 and 90 MPa were estimated by performing three-point bending tests on pre-notched beams. Crack evolution and full-field deformation in the beams were measured using the electronic speckle pattern interferometry technique. The crack characteristics, including the crack opening displacement profiles, the width of the fracture process zone and the length of the crack, were evaluated. By using a newly developed incremental displacement collocation method, the TSCs of plain concrete were determined. To facilitate the use of TSCs by commercial finite element packages, the estimated TSCs were simplified to bilinear and exponential curves, and the related parameters were determined.