Study On Static And Dynamic Mechanical Properties Of Steel Fiber Reinforced Concrete

Steel fiber reinforced concrete(SFRC)is a kind of high strength cement-based composite material formed by adding randomly distributed steel fibers into ordinary concrete.It has the advantages of high compressive strength,good durability,strong impact resistance and so on,so it is widely used in military protection and other fields.Therefore,it is of great academic significance and engineering value to study the static and dynamic mechanical properties of SFRC and obtain its response characteristics under different loads,providing necessary constitutive models and material parameters for structural design and numerical simulation.In this paper,the double-sided shear test and quasi-static compression test are carried out for SFRC with three fiber contents,and the stress-strain curves and basic mechanical properties parameters of the material are obtained.Based on the failure mode of the specimens,the shear resistance and toughening mechanism of SFRC were discussed.Based on the constitutive model of ordinary concrete proposed by Carreira and Chu,a modified quasi-static constitutive model of SFRC is obtained by introducing fiber reinforcement.Secondly,the SHPB dynamic compression test at room temperature was carried out for SFRC.The constant strain rate loading of the specimen at medium and high strain rates was achieved by using waveform shaping technology,and the linear transformation relationship between the constant strain rate and the arithmetic average strain rate was 1.35 times.Based on the principle of equivalent strain assumption,a dynamic damage constitutive equation of SFRC is obtained by introducing strain rate enhancement factor,fiber enhancement factor and damage evolution equation.Then,high-temperature SHPB tests at 200? and 400? were carried out on SFRC.The results show that the strain rate effect of SFRC at 200? and 400? is more sensitive than that at normal temperature.There is a strain rate of 60/s-80/s.When the strain rate is less than this range,its compressive strength has a temperature softening effect.The temperature effect is not obvious in this interval.When the strain rate is greater than this interval,its compressive strength has a temperature hardening effect.Finally,through self-programming,the plate impact test of C30 and C70 concrete and SHPB test of SFRC are simulated by using improved smoothed particle hydrodynamics method.The example shows that smoothed particle hydrodynamics method has good applicability in impact dynamics and the dynamic constitutive model proposed in this paper is reasonable to some extent.The above work has important guiding significance for the structural design and optimization of concrete fortifications subjected to impact collision.