Identification of the Tensile Properties of Concrete in Pre-stressed Elements Subjected to 4-Point-Bending Test

Data collected from 4-point bending tests can be exploited to determine, albeit indirectly, the tension properties of pre-stressed (actually, pre-compressed) concrete beams, which fail by fracture propagation. The overall result of these experiments depends on several factors. Cracks can vary in number and position even in nominally identical samples, and can close almost completely upon unloading. The onset and propagation of fracture in concrete elements can be detected during the loading process by high resolution cameras, which also provide input data to digital image correlation techniques. This rich experimental information can be interpreted with the support of numerical models of different realism and complexity. Their ability to obtain reliable results for parameter identification purposes, at reasonable computational costs, is discussed in this contribution.