Highlights • For post-installed anchors in tension, ductile non-Concrete Breakout(CB) failure modes dominate at deeper embedment depths. • This review summarizes the fundamental principle and research progress on non-CB failure modes. • Formation mechanisms of non-CB failure modes for different anchor types are introduced. • Current prediction models on non-CB failure modes are discussed. • Anchors in FRC and UHPC present significantly different tensile behavior. • Numerical simulation is a valid method to study non-CB failure modes.

Abstract Different failure modes occur for concrete anchors in tension. Ultimate tensile strength of anchors should be calculated per failure mode based on the design codes. Past studies mainly focus on the brittle concrete breakout(CB) failure mode, which is the most common failure mode for cast-in-place anchors installed with shallow embedment depths in normal concrete. However, for post-installed anchors, non-CB failure modes (including pull-out, pull-through, combined etc.) also occur commonly and dominate especially at deeper embedment depths. Also, a more ductile load–displacement behavior is presented in the non-CB failure modes. However, studies on non-CB failure modes are scarce. This review study is aiming to summarize the fundamental principle and research progress on the non-CB failure modes, providing references for further studies on these failure modes. Based on the working mechanisms of different anchor types (including expansion anchors, bearing-type anchors, and screw anchors) and load-bearing region and stress distributions, the formation mechanisms of non-CB failure modes are introduced. According to literatures, the characteristics of load–displacement behavior and current prediction models of different non-CB failure modes for different anchor types are introduced and discussed. The concrete capacity design(CCD) method developed for the CB mode should not be applied to the non-CB modes, and the design methods for a specific non-CB mode need further development. Based on the fracture features of base materials, the group effects of the non-CB modes are hypothesized to be reduced compared to that for the CB mode. Experimental studies on group effects of non-CB modes are needed. Numerical simulation is a valid method study the non-CB modes. Recently, newly-developed cementitious materials, such as fiber-reinforced concrete(FRC) and ultra-high performance concrete(UHPC), are widely studied and applied in constructions, and the anchors (especially post-installed anchors) in FRC and UHPC present significantly different tensile behavior; the non-CB failure modes with a more ductile behavior occur more often even at small embedment depths for anchors in FRC and UHPC. Further studies on the mechanisms and design methods for the non-CB modes for anchors in FRC, UHPC and other high-performance materials are needed to facilitate the design and application of using these materials in the connection of structures.