*3.2. Ultimate Strength*

Figure 7 shows the load–displacement curves of the short-lapped-rebar splices under tensile loading. Clearly, Specimen L20-0.15 (Figure 7c) showed an obvious yielding stage and hardening stage and it had higher strength than Specimen L20-0.10 and L20-0.05. In contrast, the yielding stage was not exhibited for Specimen L20-0.05, and it fractured at an early stage due to the limited bond strength between grout and rebar. Table 4 lists the yield strength and the ultimate strength, including the ultimate bond strength of the short-lapped-rebar splices. Compared with the conventional splices without high strength grout [20] or transverse spiral hoops [21], the ultimate strength of the short-lapped-rebar splices was significantly improved.

**Figure 7.** *Cont*.

**Figure 7.** Load–displacement curves. (**a**) L12 (**b**) L16 (**c**) L20.

As listed in Table 4, the effect of the rebar diameter on the ultimate strength of the short-lapped-rebar splices is not significant. For example, the ultimate strength of Specimen L20-0.15-1 is 1.12 times of that of Specimen L12-0.15-1 when the rebar diameter increases from 12 mm to 20 mm.
