The experimental work of this research included the test of seven columns, with dimensions of 900mm length, and cross section (150*150), a series of tests were carried out on control specimens (cylinder and prisms) for each mix for the purpose of studying the mechanical properties of reactive powder concrete such as compressive strength, splitting tensile strength, modulus of rupture and modulus of elasticity. The experimental results showed the increasing in steel fibers ratio by 2% led to the

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... increase in the compressive strength by 22.3% and increased splitting tensile strength by 329.7%, modulus of rupture by 234.44% and modulus of elasticity by 20.80%. The experimental results of the tests of slender columns indicated that increasing the steel fiber ratio from 0% led decreasing the ultimate load by 36.454 % compared to the control columns, to 2% led increasing the ultimate load by 21.685 % compared to the control columns. The results showed that of diameter steel reinforcement ratio of short columns from Ø10 led to decreasing the ultimate load by 1.859% compared to the control columns, to Ø16 led to increasing the ultimate load by 32.901% compared to the control columns. And the results showed that of spacing between of stirrups (200mm) led to decreasing the ultimate load by 4.778% compared to the control columns, to (100mm) led to increasing the ultimate load by 12.924% compared to the control columns. In the second part of this research, the ANSYS program was used as a numerical method to investigate the behavior of these columns using nonlinear analysis (Finite element). When comparing the results of experimental with theoretical side ,the theoretical results showed a