Time of dynamic impact to elements of RC frame at column buckling

A method for calculating the time of the dynamic additional impact to the elements of a reinforced concrete framing structural system under special impact caused by a sudden loss of stability of a compressed bearing element is presented. Using the discrete-linear moment-curvature diagram for reinforced concrete compressed-bended element, the analytical relationships for different stages of deformation of a reinforced concrete element before and after cracking are carried out. The obtained relationships for time of the additional dynamic impact to the elements makes it possible to determine the dynamic strength of concrete and reinforcement and the stiffness of the sections of reinforced concrete elements of structural systems under such impacts more accurately and consequently ensure more exact computational analysis to progressive collapse. (paper)