Experimental Study of Bonding Performance of Post-installed Rebar Anchors under Unilateral Pressure

Post-installed rebar (PIR) is extensively utilized for rehabilitating, strengthening, and retrofitting existing concrete structures, and its anchorage design greatly concerns the failure mode and tensile behavior. PIR anchored in joints or columns generally suffers pressures normal to its anchorage section in one direction, and PIR's failure mode and tensile behavior can be greatly affected. However, limited research on the unilateral pressure effect for PIR has been conducted, with remaining uncertainties on applications and designs for PIR. Thus, this paper carried out the pull-out tests of 38 specimens with various anchorage conditions (20 unilateral pressure specimens, 14 no-lateral pressure specimens, and four bilateral pressure specimens) to investigate the bond behavior for PIR subjected to unilateral pressure. Besides, the effects of concrete strength, rebar diameter, and anchorage length on PIR under unilateral pressure were also considered in the tests. The test results showed that the no-lateral pressure specimens split in the concrete and adhesive layer. In contrast, the unilateral and bilateral pressure specimens occurred two typical failures [adhesive-rebar (A-R) interface failure and adhesive fracture failure]. In addition, the interfacial damage and cracking pattern were discussed in detail. Then, the bond strength and bond slip of specimens were investigated. The result showed that the bond strength under unilateral pressure was greater than that under no-lateral pressure but less than that under bilateral pressure, and there was no obvious change in bond strength while the unilateral pressure increased. Regarding bond slip, it was found that the bond slip increased with the bond strength. This paper performed an experimental investigation on failure modes and cracking patterns for PIR under unilateral pressure. It analyzed the unilateral pressure effect on the bond performance for PIR, raising the safety considerations about PIR applications in load-bearing structures.