250
-+- Specimen 3
200 Specimen 4
200
150
~100
50
0 2 4 6 8 10
Displacement (in)
Figure 5-17. Moment-displacement curves for specimens 3 and 4
Experimental and Theoretical Peak Loads
The theoretical M-0 program described in chapter 4 was used to calculate
theoretical moment capacities for the piles. For the piles with CFRP grid the entire cross-
section was assumed to be confined by the grid.
The moment due to the self weight of the pile was determined by assuming a
uniform distribution (see Fig. 5-18) of the weight of the specimen. The weight of
specimen 1 was approximately 4900 lbfs and the weight of specimens 2, 3 and 4
approximately 3900 lbfs. The uniform load (w) due to the weight of the specimen is equal
to the weight divided by the length. The moment at mid-span due the self weight (Mself) is
the moment of a simply supported beam with a uniform load of w:
M wL2 (5-1)
The experimental and theoretical moment capacities are presented in Tables 5-4.
For specimens 1, 2 and 3 the theoretical moment capacities are higher than the
experimental capacities. That is an overestimate by the M-0 program. However, it should
be noted that the assumption that the entire cross-section was confined by the CFRP grid,