In order to simulate and evaluate the fiber effect and the synergetic effect of the hybrid using of fibers and stirrups on the flexural shear resistance and diagonal cracking behavior of tunnel segment, a series experiments has been conducted. Different from the conventional testing method, the symmetric inclined beams subjected to combined action of flexure, shear and axial compression were used for simulating of the loading condition of the tunnel segment. The results indicated that steel fibers can enhance the ultimate shear resistance greatly, reduce the strain of tension steel, decrease the diagonal crack width; and the combined use of steel fibers and stirrups shows a significant positive composite effect on the load carrying capacity and the failure pattern of the symmetric inclination beams. The addition of 50 kg/m3 steel fibers can transform the brittle diagonal shear failure pattern of RC beams into a ductile flexural failure pattern.Fundação para a Ciência e a Tecnologia (FCT
