The use of hybrid fibers in concrete has attracted wide attention in recent years. Using hybrid fibers with different elasticity moduli increases the strength and ductility of fiber reinforced concrete (FRC). In addition, hybrid fibers improve the shear strength of FRC beams significantly. The previous studies have shown that the hybrid use of fibers leads to a phenomenon, called synergy. However, the effect of combining hybrid fibers with stirrups is scantly studied and continues to main unknown. In this study, the effects of stirrups, concrete compressive strength, polypropylene fibers, steel fibers, and their hybrids on the shear strength of FRC beams are investigated. For this purpose, 24 FRC beams were tested in an experimental program. Experimental results show that samples with hybrid fiber have the highest shear performance. Additionally, a new model for simulating these beams' shear strength is presented, using genetic programming technique. The proposed model precisely predicts sample performance. The R2 for this model was 0.868, which is a suitable value due to the complexity of the problem. Manuscript profile