## 5 Conclusions  
Structural concrete standards adopt the experimental data coming from bending tests for considering the structural contribution of fiber reinforcement. Based on residual stress values such as \(f_{R3}\) the fiber contribution to tensile and shear strength is assessed. As it has been shown, this approach sometimes leads to different values than those obtained experimentally, even on the unsafe side. This research proposed a novel testing procedure, which complements the bending test with direct tensile and pure shear strength tests, by using the specimens previously used in the bending tests. With the use of a single initial specimen, this fiber reinforced concrete (FRC) testing methodology allows carrying out the mechanical characterization of the material by tensile bending strength tests, tensile strength tests and pure shear strength tests. This means significant savings in specimen preparation and a greater amount of information for the structural use of FRC. For that purpose, the residual halves obtained at the end of the flexural test were used for tensile and direct shear (push-off) tests and so assess the strength properties of FRC. The test was also monitored by a video-extensometry system in order to analyze the cracking displacements and patterns. Specimen preparation for direct tensile and shear tests was quite a laborious and care-taking process and was more time consuming as compared to the standard testing procedures for FRC. The test setup required detailed planning and precise positioning to prevent undesired stresses in the specimens. However, the results provide relevant information for the design of structural elements of FRC compared with the only use of bending tests. The video-extensometry system requires a previous preparation of the specimens, the correct positioning of the cameras, adequate lighting and precise focusing. The results obtained with this technique are similar to the ones provided by physical extensometers but involves complex data processing. On the contrary, it should be underlined that the images can be saved for future analyses. In addition, they can help to understand the cracking processes of FRC. The tensile tests showed a more consistent behavior than the bending test results established by the codes. In any case, the methodology proposed supplies relevant information about the tensile behavior of FRC that could be compared with the constitutive models of the Standards, thus providing reliability in the structural use of FRC. Regarding the shear tests, it should be observed that for small slipping values the behavior of steel fiber reinforcement is better than that of polyolefin fibers due to the higher modulus of elasticity and the effect of the hooked end of the steel fibers. In all cases, the Standards underestimated the shear strength for small sliding values in the range of 0.5 mm. For higher sliding values the experimental and standard values were similar with a better behavior of polyolefin fibers as compared with steel fibers. Figure 14: (**a**) Virtual strain gauges placed on the ligament of a push-off specimen. (**b**) Sliding-opening crack curves obtained by video-extensometry. The video-extensometry of the shear tests allowed the assessment of the sliding and crack opening values at the crack discontinuity. Such values may be quite relevant for the study of the FRC behavior when subjected to shear according to the shear-friction model theories. Moreover, the methodology proposed in this study provide the designer with values of shear strengths coming from push-off tests. It is important to remark that if these tests are not performed, the shear structural design would be developed through the use of residual strengths extracted from bending tests, as shear reinforcement mechanisms are different from bending reinforcement mechanisms. The proposed methodology is applied to various types of concrete and fibers in order to show the versatility of the proposal and the difficulties of some tests.