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,