Click for next page ( 34


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 33
33 Table 40. Analysis of variance for unconfined repeated load permanent deformation response. Cycle ITC IPC MDTS Grand Pooled Analysis of Variance Avg SSW Avg SSW Avg SSW Avg COV SSB MSW MSB F Fcr Conclusion 1 0.04 0.0000 0.05 0.0000 0.06 0.0001 0.05 6.02 0.0014 0.0000 0.0007 55.85 4.26 Permanent strains are different 16 0.23 0.0008 0.27 0.0002 0.27 0.0008 0.26 4.67 0.0040 0.0002 0.0020 10.42 4.26 Permanent strains are different 25 0.28 0.0010 0.33 0.0002 0.33 0.0012 0.31 4.54 0.0050 0.0003 0.0025 9.36 4.26 Permanent strains are different 40 0.34 0.0020 0.39 0.0002 0.39 0.0017 0.38 4.77 0.0063 0.0004 0.0031 7.32 4.26 Permanent strains are different 63 0.41 0.0026 0.46 0.0002 0.46 0.0024 0.45 4.68 0.0065 0.0006 0.0033 5.58 4.26 Permanent strains are different 100 0.49 0.0048 0.54 0.0003 0.54 0.0039 0.52 5.23 0.0082 0.0010 0.0041 4.10 4.26 Permanent strains are the same 160 0.58 0.0072 0.64 0.0005 0.63 0.0066 0.62 5.58 0.0088 0.0016 0.0044 2.77 4.26 Permanent strains are the same 250 0.69 0.0130 0.75 0.0007 0.74 0.0105 0.73 6.19 0.0094 0.0027 0.0047 1.75 4.26 Permanent strains are the same 400 0.83 0.0219 0.89 0.0015 0.88 0.0192 0.87 6.88 0.0090 0.0047 0.0045 0.95 4.26 Permanent strains are the same 630 1.01 0.0377 1.07 0.0032 1.06 0.0375 1.05 7.70 0.0080 0.0087 0.0040 0.46 4.26 Permanent strains are the same 1000 1.30 0.0721 1.35 0.0078 1.33 0.0871 1.32 8.91 0.0056 0.0186 0.0028 0.15 4.26 Permanent strains are the same 1600 1.80 0.1451 1.84 0.0225 1.80 0.2871 1.81 10.75 0.0034 0.0505 0.0017 0.03 4.26 Permanent strains are the same 2500 2.91 0.4842 2.89 0.0964 2.83 1.7224 2.88 15.22 0.0152 0.2559 0.0076 0.03 4.26 Permanent strains are the same The permanent deformation curves in Figure 20 are for un- permanent deformation response from different machines. confined tests; those in Figure 21 are for confined tests. For The analysis for selected load cycles is presented in Table 40 unconfined tests, flow occurred at approximately 1,000 cycles. for the unconfined tests and Table 41 for the confined tests. Flow did not occur in the confined tests. The sections below The data in Table 40 indicate a significant difference in the discuss the statistical analysis of these data. permanent deformation response between devices early in the tests up to approximately 100 load cycles. Although there is a significant difference and based on the Duncan multiple 3.3.1 Statistical Analysis range test, the permanent deformation from the ITC device Analysis of variance as discussed previously in the dy- is significantly lower than the other two, the difference is only namic modulus section was used to analyze differences in the 0.05 percent, which is not significant from an engineering Table 41. Analysis of variance for confined repeated load permanent deformation response. Cycle IPC ITC MDTS Grand Pooled Analysis of Variance Avg SSW Avg SSW Avg SSW Avg COV SSB MSW MSB F Fcr Conclusion 1 0.14 0.0001 0.13 0.0100 0.14 0.0009 0.13 22.83 0.0002 0.0014 0.0001 0.06 4.46 Permanent strains are the same 16 0.55 0.0032 0.52 0.2046 0.52 0.0229 0.53 26.14 0.0017 0.0288 0.0008 0.03 4.46 Permanent strains are the same 25 0.64 0.0063 0.61 0.2692 0.62 0.0304 0.63 25.58 0.0017 0.0382 0.0009 0.02 4.46 Permanent strains are the same 40 0.74 0.0082 0.72 0.3464 0.73 0.0432 0.73 24.99 0.0009 0.0497 0.0004 0.01 4.46 Permanent strains are the same 63 0.84 0.0133 0.84 0.4260 0.84 0.0602 0.84 24.40 0.0001 0.0624 0.0001 0.00 4.46 Permanent strains are the same 100 0.96 0.0191 0.98 0.5152 0.96 0.0862 0.96 23.69 0.0010 0.0776 0.0005 0.01 4.46 Permanent strains are the same 160 1.09 0.0279 1.13 0.6066 1.09 0.1218 1.10 22.88 0.0046 0.0945 0.0023 0.02 4.46 Permanent strains are the same 250 1.23 0.0394 1.30 0.6931 1.23 0.1735 1.25 22.12 0.0128 0.1133 0.0064 0.06 4.46 Permanent strains are the same 400 1.39 0.0573 1.49 0.7840 1.39 0.2531 1.43 21.37 0.0277 0.1368 0.0139 0.10 4.46 Permanent strains are the same 630 1.57 0.0713 1.71 0.9001 1.56 0.3657 1.61 20.86 0.0544 0.1671 0.0272 0.16 4.46 Permanent strains are the same 1000 1.77 0.0857 1.96 1.0391 1.74 0.4888 1.82 20.31 0.1052 0.2017 0.0526 0.26 4.46 Permanent strains are the same 1600 2.00 0.0963 2.23 1.2087 1.94 0.6473 2.06 19.77 0.1810 0.2440 0.0905 0.37 4.46 Permanent strains are the same 2500 2.26 0.0954 2.51 1.3856 2.16 0.8518 2.31 19.21 0.2682 0.2916 0.1341 0.46 4.46 Permanent strains are the same 4000 2.62 0.0746 2.85 1.5940 2.41 1.1233 2.63 18.45 0.4015 0.3490 0.2007 0.58 4.46 Permanent strains are the same 6300 3.06 0.0966 3.22 1.8747 2.67 1.4255 2.98 17.91 0.6448 0.4246 0.3224 0.76 4.46 Permanent strains are the same 10000 3.50 0.3918 3.62 2.1780 2.96 1.7957 3.36 18.23 0.9769 0.5457 0.4884 0.90 4.46 Permanent strains are the same

OCR for page 33
34 1.0 0.9 0.8 Permanent Strain, % 0.7 0.6 ITC 0.5 IPC MDTS 0.4 0.3 0.2 0.1 0.0 0 20 40 60 80 100 Load Cycles Figure 22. Comparison of permanent deformation response for the early portion of the unconfined repeated load tests. standpoint. Figure 22 compares to early portion of the perma- significant differences more difficult to detect. Figure 23 is a plot nent deformation curves for unconfined tests with the three showing the coefficient of variation for confined and uncon- devices. fined tests as a function of axial strain in the specimen. The co- The data in Table 41 indicate that there is not a significant efficient of variation plotted in this figure is a pooled value based difference in the permanent deformation response for confined on data from the three machines. The coefficient of variation in tests using different equipment. However, confined testing has the unconfined test increases with increasing axial strain, while greater variability compared to unconfined testing making it decreases with increasing strain in confined tests. Before, the 30 25 Coefficeint of Variation, % 20 Unconfined 15 Confined 10 5 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Permanent Strain, % Figure 23. Coefficient of variation for unconfined and confined repeated load tests.