Research On Anti-Penetrating Performance Of New Type Combined Concrete Protective Structure

Steel-fiber reinforced concrete has already been applicated in military protective structures and nuclear facilities successfully. However, the concrete in these structures possibly is in risk of fire hazard or high temperature. At the same time, the concrete may suffer the impact load. For the typical characters of concrete such as high brittleness and low tensile strength, the protective capability of concrete protective structures is generally deficiency when the structures get projectile penetration. Thus, in this paper,Φ40mm SHPB (Split Hopkins Pressure Bar) was adopted to investigate the dynamic mechanics capability of steel-fiber reinforced concrete exposed to high temperature. A combined steel-fiber reinforced concrete structure is designed to improve the capability of penetration. The process of projectile penetrating concrete target is numerical simulated.The statics performance of steel-fiber reinforced concrete with different steel-fiber contents exposed to high temperature was investigated. SEM was adopted to analyse the microstructure alteration of SFRC exposed to high temperature. The results of compressive and splitting strength were fitted respectively. The relationship between compressive strength and temperature is according with the function of Boltzman. The relationship between splitting strength and temperature is accord with the function: y = y0 +Ae?x/t. The transformation of microstructure of SFRC exposed to high temperature is according with the marco-mechanics. Along with the increasing of temperature, the micostucture of hydrated procucts in concrete matrix changes. The matrix loosens from compaction. There are much cracks observed with the temperature gets higher. After exposed to high temperature, there are clearances and cracks occurring between the matrix and aggregate. The felting capability is weakened. At the same time, the binding between stee fiber and matrix also decreases.Combined with strain gauge measurement method, the modified split Hopkinson pressure bar was adopted to investigate the dynamic behaviour of steel-fiber reinforced concrete exposed to high temperature under impact load. The stress-strain curves can be obtained accurately. The error from manual sampling in the early phase of curves is avoided. The experiment results show the ultimate stress of SFRC decreases with the increasing of temperature. There is little influence of high temperature on elasticity modulus of SFRC. The damage of SFRPC is much lower than SFRC. The elasticity modulus of SFRPC with various W/B decreases obviously with the increasing of temperature. With the increasing of W/B, the residual dynamic strength of SFRPC increases also.A new concrete protective structure is suggested in this paper. The structure is combined of multi-material. The SFRPC, steel pipe concrete and aluminium foam combined structure is adopted to improve the anti-penetraion capability of concrete target. TheΦ12.7mm LGG was employed to penetrate 15 concrete targets. The scale of concrete target is 360mm×360mm×400mm. The results show that the depth of penetration of combined structure decreases one-third of the targets made of single SFRC.The calculation software of finite element AUTODYN is employed to simulate the process of projectile penetrating the SFRC target and the combined structure target. The destroy conformation of targets, velocity variation of projectile during penetration are simulated accutately.