Bond Behavior of Post-Installed Rebar Under One-Way and Two-Way Transverse Pressure

Post-installed rebars are extensively used in the strengthening and rehabilitation of concrete structures, where compressive stresses in the anchorage zone provide transverse pressure and significantly affect bond behavior. However, it remains unclear how different transverse pressure conditions, particularly one-way and two-way transverse pressure, influence the bonding behavior of post-installed rebars and how their effects differ. To address this gap, this study investigates the effects of one-way and two-way transverse pressure on the bond mechanism and failure mode of post-installed rebars. To achieve this, 22 pull-out tests were carried out under two transverse pressure configurations, namely one-way and two-way transverse pressure, with pressure levels ranging from 0 to 12 MPa. The results show that, without confinement, concrete splitting was the dominant failure mode, whereas under transverse pressure, failure shifted to adhesive failure or adhesive–rebar interface failure. Transverse pressure significantly improved bond strength, with maximum increases of 49.9% under one-way transverse pressure and 82.9% under two-way transverse pressure. Both the transverse pressure configuration and pressure level had a significant influence on failure evolution and bond performance. In general, increasing the pressure level enhanced the interfacial bonding capacity; however, one-way transverse pressure tended to induce stress concentration in the adhesive layer, thereby promoting adhesive-related failure. These findings clarify the role of transverse pressure conditions in the anchorage behavior of post-installed rebars and provide a basis for the design and analysis of post-installed rebar anchorage systems.