wer 1OKm | | = r ozol. | | T_ O2 :a: 0.5 0, | = =2& o10 [| wW 0 4 Qo O15 Re | oe a a 5 - 6 ~0.5 -— _ 0,05 -— =10 4 0 5 | 10 | 15 I 20 25 TIME, SEC Fig. B.5— Displacement from velocity data of Fig. B.3. B.7 \\ y | io | t2 y | 14 TIME, SEC | 16 Fig. B.6-—Displacement from velocity data of Fig. B.4. EVALUATION Evaluation of corrected doubly integrated acceleration-time data is important. Admittedly the example just described is an extreme case involving data which for practical purposes are useless, The actual accomplishment of the correction process in this case was elimination of features of the raw data which, because of duration or period, were judged to be extraneous to pertinent data. As a result significant portions of the velocity and displacement data could be plotted to scales 20 times those feasible for results of the initial integration. The final displacement curve does not depict true motion but gives a reasonable indication of magnitude and a rough idea of the displacement-time pattern. Less complex data involving accelerations of damaging magnitude, high signal-noise ratios, short periods of time, and relatively simple signal patterns, such as those from a clean air shock or close-in on an underground explosion, in general can be corrected by the procedures described. Correction of data in this category, if necessary, is usually much less complex, involving only one or two linear corrections in the first integral, and the results are correspondingly more accurate. Data from short-duration clean signals canbe fitted to the terminal condition of vanishing velocity with more certainty than complex longer signals. Consequently velocity and displacement components of ground motion can be derived by integration of acceleration data with considerable confidence when the data represent ground motion in the area where signal strength is high and durations are relatively short, Fortunately this area includes all ground ranges in which motion of damaging proportions will exist. 55-56