r - The Hong Kong Polytechnic University

Table 1 (Contd.) Test and predicted flexural debonding moment
Reference Specimen M e ε e M p* /M e M p** /M e M Oeh /M e M T-Y /M e
(kNm) (µε) (kNm) (kNm) (kNm) (kNm)
Oehlers (1992) 7/2/* 13.5 - 0.9 1.1 0.8 1.0
8/2/* 12.9 - 0.9 1.0 0.7 0.9
Yao & Teng (2007) CS-A 12.5 1158 1.3 1.4 4.9 1.2
CS-L1-A 17.0 2425 1.3 1.3 6.6 1.0
CS-L3-A 13.5 919 1.1 1.2 4.0 1.0
CS-W50-A 13.8 1689 1.7 1.5 3.7 1.1
CS-W100-A 13.3 1038 1.4 1.3 4.3 1.1
CP-A 11.4 404 1.2 1.4 4.1 1.1
SP-A 11.5 215 1.1 1.1 2.9 0.9
GS-A 19.1 2924 1.2 1.4 8.2 0.9
CS-C10-A 18.9 1540 1.1 1.2 4.9 0.9
CS-C50-A 11.9 1211 1.1 1.1 4.0 1.1
Smith & Teng (2003) 6-A 17.0 - 1.0 1.0 3.4 0.8
Mohomed Ali FP-S-5 26.3 325 1.3 1.2 0.7 0.8
et. al. (2001) FP-C-8.5 28.1 342 1.2 1.1 0.7 0.8
FP-CG2-16 28.0 455 1.3 1.2 0.9 0.9
FP-G-32 40.4 809 1.2 1.1 1.1 0.7
FP-CG-16 62.1 1775 1.1 1.0 1.4 0.7
Note: * with Lu et al’s (2005b) bond model; ** with Seracino et al’s (2007) bond model
2.0
2.0
1.5
1.5
Mp* / Me
1.0
Mp** / Me
1.0
0.5
0.0
Average
95% lower bound
0 500 1000 1500 2000 2500 3000
ε e (x10 -6 )
(a) With Lu et al.’s (2005b) bond parameters
Figure 7 Comparison of model predictions with test data
NEW FLEXURAL DEBONDING STRENGTH MODEL
0.5
0.0
Average
95% lower bound
0 500 1000 1500 2000 2500 3000
ε e (x10 -6 )
(b) With Seracino et al.’s (2007) bond parameters
A new theoretical model developed in this section directly employs the theoretical debonding moment M p (Eq. 9)
from the preceding interfacial shear analysis, i.e.
δ f
M p = φ1
(13)
m λ
where λ and m are given in Eqs 3b-c in which the parameters A 1 and I 1 should be replaced respectively by A c,0
and I c,0 that are the elastic sectional properties of the cracked unplated beam section. Coefficient φ 1 is introduced
in Eq. 13 so the model can be turned into a lower bound design model.
Calculation of M p (Eq. 13) needs the bond properties δ f ; τ f and G f for which any bond models such as Lu et al.’s
(2005b) or Seracino et al.’s (2007) can be used. This is referred as M p* and M p** respectively when the above
two bond models are used. The statistical results of prediction-to-test using both bond models give similar
accuracy (Table 2). For predicting the debonding strength, φ 1 = 1.0, and Eq. 13 is the same as Eq. 9. Based on
the data presented in Table 1, φ 1 = 0.737 or 0.701 for the 95 percentile (1.645 × standard deviation) lower bound
respectively when Lu et al. (2005b) or Seracino et al. (2007) bond parameters are used.
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