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Strains Induced in Urban Structures; a Case StudyThis study measured and interpreted strains induced in two, multiple story, older, urban structures (Art Student League and Fire Station Buildings) by ultra-high frequency rock blast excitation from contiguous excavation. The strains were obtained from relative displacements found by integrating time correlated velocity time histories from multiple positions on the structures and foundation rock. Observations are based on ten instrumented positions on the structures and in the foundation rock during eight blast events, which provided over seventy time histories for analysis. The following conclusions were made based on the study: Despite particle velocities in the rock that greatly exceed regulatory limits, strains in external walls are lower than those necessary to crack masonry structures and weak wall covering materials. These strains are also lower than those sustained by single story residential structures when excited by low frequency motions with particle velocities below regulatory limits. The full-length Fulbright Visiting Report can be found here and the full-length pre-publication case study can be found here. Press here for a one page summary of this study and the accompanying single figure comparison of "urban" and "house" excitation and response. Raw data in Excel format resulting from the eight blast events is available for independent analysis and study below. Each Excel book contains numerous sheets of time histories, which are identified by building and transducer number. Transducers are further identified by building, location, and direction. For clarification: building (1 = art, 2 = fire station), location on building (S1 or B = below, lower, approx. street level, S2 or A = above, higher, approx. top of building) and G = in-rock), and direction (radial, transverse = into excavation). Again, for details refer to the reports linked above. Note: Some of the Excel files have sheets with displacement calculated, but for independent study refer to only the velocity data as it is the original data.
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