Elastic limit tensile stress of UHPFRC: Method of determination and effect of fiber orientation

This paper discusses the influence of fiber orientation on elastic limit tensile stress of ultra-high performance fiber reinforced cementitious composites (UHPFRC). An original model relating elastic limit tensile stress to fiber orientation is proposed, and three determination methods of the elastic limit are compared. Five specimens are tested under uniaxial tension and characterized with digital image correlation, acoustic emission and displacement transducers. Before testing, the fiber distribution (local dosage and orientation) of each specimen is determined using a magnetic probe. After testing, three methods (offset with 2 different threshold values, and deformation modulus drop) are applied to determine the elastic limit tensile stress. The test results show that the proposed model estimates well the elastic limit tensile stress on the basis of fiber orientation. The modulus-drop method yields the most representative value for the elastic limit considering the underlying physical phenomena. It may be taken as definition of elastic limit tensile stress of UHPFRC.