Crack Response to Long-Term Environmental and Blast Vibration Effects

This paper synthesizes seven case histories of micrometer changes in the width of cosmetic cracks in a wide range of wall materials and structure types produced by long term (environmental) and transient (blast vibration) effects. Long term crack response over periods of days to weeks is compared to changes in temperature and humidity. Transient crack response is compared to peak velocity ground motions and structural response. It was found that long term, weather-induced crack response can be more than 1 order of magnitude larger than that induced by noticeable ground motions of 2.5 mm/s (0.1 in./s) and that crack response correlates best with wall shear strains.