*3.4. Bond Slip Behavior*

On the basis of the values of SMs, the slip displacement *s* between the grout mortar and the anchored rebar can be obtained from Equation (1).

$$s = \left(\mathcal{S}\_{SM1} - \mathcal{S}\_{SM2}\right) - \left(\mathcal{S}\_{SM2} - \mathcal{S}\_{SM3}\right) \tag{1}$$

where *SM*1 is the displacement of the anchored rebar in the loading end, *SM*2 is the displacement of the anchored rebar in the anchorage end, and *SM*3 is the displacement of the short-lapped-rebar splices.

The total bond stress between the grout mortar and the anchored rebar is the sum of the bond stress *τ*<sup>i</sup> from the loading end to the anchorage end, as shown below.

$$
\pi = \frac{P}{\pi d l\_l} \tag{2}
$$

where *P* is the axial load applied to the loading end of the anchored rebar, *d* is the diameter of the anchored rebar, and *l*<sup>l</sup> is the lapped length of the anchored rebar.

Figure 10 shows the relationships between the total bond stress *τ* and the slip displacement *s*. Clearly, the total bond stress increases linearly with the increase in the slip displacement. The maximum bond stress (the ultimate bond strength) reaches 35 MPa, which is approximately 1.4 times that in conventional specimens [23,24].

**Figure 10.** *Cont*.

**Figure 10.** Bond and slip relationships in Specimens. (**a**) L12-0.05 (**b**) L16-0.05 (**c**) L20-0.05.
