EXPERIMENTAL STUDIES ON SHEAR CAPACITY OF DISC ANCHORS IN LOW STRENGTH CONCRETE

Conventional post-installed anchors are widely used in the retrofit works of existing buildings where new reinforced concrete members are attached to the existing structure. Especially in the case of using externally added frames for retrofit, failure of anchors and disintegration of retrofit members can threaten the safety of the entire structure. Considering the fact that, existing structures that requires retrofit generally exhibits quite low concrete strength, it is crucial for the anchors to safely transfer shear forces between existing and new members. Conventional anchors subjected to shear forces tend to fail due to shear yielding of anchor bolts or crushing of concrete. Integrated Disc Anchors on the other hand, can provide a reliable solution with substantially enhanced shear capacity. Unlike conventional anchors, Disc Anchors consist of a disc-shaped head integrated with the actual anchor. In application, Disk Anchor is installed into existing concrete members so that disc remains on the connection surface of connecting members and as the disk of the anchor is much larger than conventional anchors, shear force can be effectively transferred between members even in the case of low strength concrete. A bolt screwed into the Disc Anchor that remains in the new added member ensures the connection. In this study, shear capacity of Disc Anchors was investigated through experimental works. A set of pure shear experiments was conducted to comprehend the behavior of the Disc Anchors with two different embedment depth in low strength concrete grades ranging between 8MPa to 16MPa compressive strength. The test results show that, disc anchors exceeded the design shear force levels determined according to relevant guidelines. Moreover, disc anchors experienced a significant deformation after reaching a maximum strength with a slight decrease in shear capacity due to their greater material quality and shear transfer surface. A simple shear behavior model is proposed for analytical applications of the Disc Anchors, as well.