Numerical simulations of nonlinear seismic torsional pounding between two single-story structures

Nonlinear seismic torsional poundings between two asymmetric singlestory structures are investigated numerically. The torsional vibrations of these structures are modeled by 2 translational displacements and 1 rotation, and the impact force is modeled by the nonlinear but frictionless Hertz contact. Thirteen pounding scenarios are used to check for impact occurrence during the numerical integration. Inclusion of torsional response leads to more chaotic responses, comparing to the translational poundings considered by Chau and Wei (2001). For certain excitation periods, numerical simulations result in periodic group poundings that have been reported experimentally by Chau et al. (2003), and these periodic group poundings do not exist for the cases of non-torsional poundings. When the separation distance between the two structures increases, the chance of poundings decreases but the magnitude and shape of the relative impact velocity spectrum remain roughly the same. In general, relative impact velocity decreases with the translational damping ratio, but is less sensitive to the torsional damping ratio and to the value of eccentricity.