Abstract
Seismic pounding of two closely-spaced buildings can be a serious hazard, and adequate building separation distance must be used to preclude pounding. It can be calculated as the peak value of the relative displacement between the buildings through time history analysis. For an alternative and more practical estimate, the writers proposed the "spectral difference (SPD) rule" that simply uses the buildings' oeak displacements. The present paper proposes a simplified method combining the rule with elastic response spectrum to approximate peak inelastic displacement of each building. Utilizing this SPD-based method, the paper clarifies the relative displacement trends based on building periods, damping ratios, ductility demands, and earthquake soectral characteristics. The method is validated and various trends discussed by using numerous code-comoatible building pairs and 33 earthquakes. The SPD-based method is shown to be much more accurate than other simplified methods, due to its ability to account for the inelastic vibration phase of two buildings. The results are also readily applicable to the problem of finding a necessary sliding seat distance to prevent falling of a bridge, which is supported by two separate structures developing relative motion.
