The experimental results are summarized in Table 5 and include (1) tensile strength, (2) tensile strain, (3) average crack width at 0.2% tensile strain, and (4) average bond strength (u) determined by summing the forces parallel to the reinforcement axis, assuming that the bond stress
levels are distributed uniformly over this length , as follows:
Therefore, the three parameters, as shown in Figure 10, the initial stiffness, the value of the softened contact relationship slope, and the maximum bond stress
need calibrating against experiments in order to define the contact model.
The force transferred from the concrete to the reinforcing steel was calculated using Equation (1), while the bond stress
which occured in the reinforcing steel element was obtained by Equation (2).
The most recent consolidated third party cash flow statements which incorporate various Fitch interest-rate and bank bond stress
scenarios, demonstrate a minimum asset parity ratio of 114.3% for the remaining life of the bonds.
The dimensions arisen during stressing operations, and the bond stress
along the tendon bond length were determined in next steps (Stefanak 2013):
where: [[lambda].sub.1] is the expected pull-out length ratio; [[lambda].sub.2] is the fibre orientation factor; [[lambda].sub.3] is the group reduction factor associated with the number of fibres pulling out per unit area; [tau] is the average bond stress
of a single fibre embedded in the concrete; [V.sub.f] is the fibre volume percentage; [beta] is the bond factor, accordingly to Campione (2008), can be assumed being equal to 0.5 for round fibres, 0.75--for crimped fibres, 1.0--for hooked fibres; [l.sub.f] and [b.sub.f] are the length and the diameter of fibre, respectively.
The bond stress
and the shear resistance in the pre-existing crack portion are assumed to be zero.
Stresses predicted by bond stress
analysis and lap shear strength as a function of adhesive modulus.
where A is the contact area between the inner wall of the steel tube and the core concrete; A = 4(B - 2t)[l.sub.a], where [l.sub.a] is the interface length of the bond stress
between the steel tube and the core concrete.
The bond stress
can be calculated assuming a uniform bond stress
distribution along the embedded length of the bar in concrete using
However, the intensity of the stress is less than the bond stress