log (E ] =
3
3.28273 2.1435 log (D D ) + 0.3655 log (D D )
4 10 1 4
- 2.10305 log (t ) + 0.266174 log (E /E )
1 1 2
+ 0.005057 (E ) log (D D ) + 5.54315 (1/E )
2 4 10 4
- 3.78662 (1/t ) + (0.278664 x 10-6)(E E )
1 1 4
- 9.41778 x 10-6(E E ) + 0.0015423 (E /E )
2 4 1 2
- 7.34825 x 10-5(E t ) 0.024136 (E /E )
1 1 2 4
- 0.135502 (E /E ) log (D D ) Eqn. 4.14
2 4 4 10
Equation 4.14 has an R2 of 0.933 with a total of 134 number of cases.
The reliability of this equation is discussed under Prediction Accuracy.
The third E3 prediction equation was developed from a limited range
of variables using D4 D as the basic independent variable. The
resulting equation (Equation 4.15) was later found to be applicable to a
wider range of variables when field measured Dynaflect deflections were
analyzed.
Case 3. For 1.0 < t < 3.0 in., 150.0 < E < 500.0 ksi,
1 1
38.0 < E < 55.0 ksi, 18.0 < E < 30.0 ksi.,
2 3
and 14.0 < E < 22.0 ksi,
4
-1.1256
= 8.606 (D D )
4 7
Eqn. 4.15
(N = 12, R2 = 0.991)