An experimental and analytical investigation was conducted in order to study the effect of axial compression forces on the shear behavior of high strength fiber reinforced concrete (HSFRC) beams. Nineteen simply supported HSFRC beams were subjected to axial compression forces and tested under two-point vertical loading for three values of shear span to depth ratio. The studied beams contained variable amount of fiber content, two types of fibers (corrugated shape and hooked-end), variable amount of web reinforcement. It was found that the shear strength of beams subjected to axial compression stress level equals 0.1, is higher than that in the literature for beams tested without applying axial stress by a range of 22-98%. In addition, increasing the axial compression stress level to 0.2 led to an increase in the first crack load, ultimate load by 24% and 10%, a reduction in the deflection by (19-30%), compared with those subjected to axial compression stress level equals 0.1. The effect of increase of axial compression stress level becomes less significant with the increase in percentage volume of fibers from 0.5% to 1.5%. A combination of web reinforcement and fibers resulted in a significant increase in the cracking and ultimate loads by 123% and 59%, respectively, over those of the reference beam. A new formula is proposed for predicting the shear strength of HSFRC beams subjected to axial compression. The results obtained by the proposed formula are in a better agreement with the test results when compared with the predictions based on codes of practice such as the ACI 318-99, and the ECCS 203-2001 and the empirical equations proposed by other investigators.
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