Experimental investigation on post‐installed anchorages with cast‐in anchor reinforcement under tension loading

Anchors are used to connect different structural and non‐structural components to reinforced concrete structures. Anchorages when subjected to tension loading might fail in different failure modes, with concrete cone breakout (CCB) being one of the most common. The capacity of an anchorage against CCB can be significantly enhanced by means of anchor reinforcement (also known as supplementary reinforcement in Europe) placed strategically around the anchorage. In case of anchorage with anchor reinforcement, as the crack corresponding to CCB intercepts the anchor reinforcement, it starts to act as a stitching system between the structural body and the breakout body. There are different models available in design codes and literature to calculate the capacity of cast‐in anchorages, like embed plates, with cast‐in anchor reinforcement. Using post‐installed anchors is a popular choice due to their flexibility in terms of design and setting location. However, only overly conservative models are available in standards for post‐installed anchors with anchor reinforcement. This is primarily due to the lack of experimental evidence. Therefore, an experimental investigation was performed in this work using post‐installed anchors with cast‐in anchor reinforcement under tension loading to understand the behavior and verify the performance of post‐installed anchorages when used in conjunction with cast‐in anchor reinforcement. Three types of post‐installed anchors with different load‐transfer mechanisms, namely adhesive anchors, undercut anchors, and torque‐controlled expansion anchors, were tested under concentric tension loading varying the amount and layout of the cast‐in anchor reinforcement. In general, the behavior of post‐installed anchorages with anchor reinforcement was found to be similar to the behavior of cast‐in anchorages with anchor reinforcement. Higher load capacity and larger failure displacement were observed for all three types of anchors when anchor reinforcement was used compared to the reference tests without any anchor reinforcement.