Response of axial-loaded steel-concrete composite walls under low-velocity impact

Steel-concrete (SC) composite walls consisting of two external steel plates and sandwiched concrete core have been employed in various engineering structures such as nuclear facilities, protective structures and high-rise buildings. Impact resistance performance is an important aspect for designing this type of structures. This paper experimentally and numerically studies the low-velocity impact response of axial-loaded SC composite walls. A total of six SC composite walls were fabricated and tested by using drop hammer to obtain damage mode, impact force and mid-span deformation. Effects of impact height (impact energy), steel plate thickness, shear connector type and axial-load ratio were analyzed. The specimens experienced severe local indentation at the impact location. As the axial-load level increased from 0 to 0.2, the indentation area, concrete cracking and global deformation was reduced, indicating the axial-load could effectively enhance the impact-resistant capacity of the SC walls. Additionally, finite element (FE) models were developed and validated using test data. The verified numerical models were then employed to analyze the impact process and energy dissipation mechanism as well as the influences of key parameters on the dynamic responses. After that, a simplified formula was suggested to estimate the maximum mid-span deformation of SC composite walls under impact loading.