INVESTIGATION OF DYNAMIC CONSTITUTIVE MODEL OF STEEL FIBER CONCRETE UNDER CONVENTIONAL TRI-AXIAL COMPRESSION

The steel fiber content of 0%, 1%, 2%, 4%, 6% of the C30 and C40 concrete were conducted on the conventional three-axis experiment for a regular three-axis dynamic compression test. The confining pressure values of 0, 6, 9, 12, 18 and 24 MPa were used on the C30 concrete specimens, the confining pressure values of 0, 8, 12, 16, 24 and 32 MPa were used on the C40 concrete specimens; The concrete specimen is loaded in certain sine-wave pressures in axis grade by grade. On this basis, the expression of the stress-strain curve was chosen and analyzed, the correlation of the material parameters and the factors were analyzed. The results show that: 1) the stress-strain curve formula parameters using for the SFRC under static force presented by Ezeldin are modified, the modified model has a good description of the stress-strain curve of the SFRC under the three-axis dynamic compression; 2) fiber content on dynamic role of improving the compressive strength of the C40 concrete show more significant than that of C30 concrete, but the improvement of the fiber content to the dynamic strength of the concrete is not considerable under pressure; 3) the concrete dynamic peak stress shows more sensitive on confining pressure size; comparing with C30, the sensitivity of C40 is slighter; the peak strain relationship among other factors is basically the same as that of the peak stress; 4) under dynamic loading, the performance of C40 is higher than that of C30 on the secant elasticity modulus, the relationship between the secant modulus and the steel fiber content; 5) the confining pressure and fiber content of concrete have not much impact on the index toughness on the state of compression.