Analyses of low-rise building damage

Statistical studies were conducted to correlate ground motion with structural damage data from damaging and nondamaging underground high-yield nuclear test explosions detonated during the period from 1968 to 1976. Correlations were established for overall motion-damage relationships, given in terms of incidence of complaints, incidence of damage, and damage cost. Although the correlations established are within statistically acceptable limits, they could not be mathematically defined by simple analytical functions. Also, significant scatter or randomness in the damage statistics was noted for the low ground motion amplitude events. This observed scatter may be attributed either to the fact that damage is not highly dependent on ground motion in the low amplitude range or that credible damage in this range is substantially affected by other factors, such as variations in low ground motion amplitude, wind, or geological conditions. Studies were also conducted to correlate the areal distribution of damage to variations in short-period ground motion and also to active geological conditions in Las Vegas, Nevada. Geological conditions studied included water table drawdown and unstable surficial soils. No strong correlation was observed for either ground motion or geological factors. The short-period ground motion amplitudes tended to be randomly distributed, indicating that other factors, such as extraneous vibratory noise, may have caused the motion to appear random. These study results indicate that the various active geologic conditions in the Las Vegas Valley induce stresses in building components and that damage is triggered by significantly varying the amplitudes of low-intensity ground motion