Probabilistic Evaluation of the Separation Distance between Adjacent Systems (2001-2002)

The ABS(ABSolute sum), SRSS(Square Root of Sum of Squares) and DDC (Double Difference Combination) rules for the assessment of the separation distance between adjacent structures are probabilistically evaluated through numerical simulations. Structures are modeled as SDOF systems, both linear and nonlinear. Ground acceleration histories are synthetically generated from modified Kanai-Tajimi power spectral density functions. Both wide-band and narrow-band excitations are considered. Results show that none of the rules considered in this study are satisfactory in the sense that they indicate separation distances whose probability of exceedance (i.e., the probability of pounding or collision) is not equal to the probability of exceedance of the displacement response of the individual systems. The ABS rule is consistently conservative, but its degree of conservatism is generally excessive. The SRSS and DDC rules provide conservative or unconservative results depending on the characteristics of the excitation and the relationship between the fundamental periods of the systems.