Dynamic responses and damage mechanisms of low-rise reinforced concrete frame structures subjected to rockfall impacts

Combined with the validations of the nonlinear material models, this study addresses the nonlinear dynamic response, damage mechanisms and failure modes of reinforced concrete frame structures under rockfall impacts, utilizing explicit dynamic analysis software for detailed model of structures. The findings indicate that the peak impact force is primarily influenced by the impact velocity and subsequently by the impact mass, while the impact location exerts the least influence; A linear relationship is observed between the maximum impact force and rockfall diameter, whereas a nonlinear association exists with rockfall velocity; Predominant failure modes include global and local failures, with damage and failure predominantly concentrated on the impacted columns and their surrounding components; Notably, similar damage levels were observed for corner and edge middle columns of structures under rockfall impacts; The column base, mid-column and column top primarily exhibit flexural-shear failure, flexural failure and flexural-shear failure, respectively; Given the higher rate of plastic energy absorption during mid-column impacts compared to column base and top impacts, a rockfall striking mid-column results in higher dynamic response and greater structural damage. This study can provide useful reference in design and restoration of low-rise reinforced concrete frame structures located in areas prone to frequent geological disasters.