What are the adhesive anchor failure modes in shear?

The adhesive anchor failure modes in shear primarily involve interactions between the anchor and the surrounding concrete, emphasizing various mechanisms that can lead to failure when shear loads are applied. In the context of this question, the option that is identified as correct highlights three key failure mechanisms: steel failure, concrete pryout failure, and concrete breakout failure.

Steel failure occurs when the anchor itself deforms or fractures under the applied shear load. This is particularly relevant for adhesive anchors that rely on the tensile strength of the anchored steel rod or bolt, which can fail if the shear forces exceed this tensile capacity.

Concrete pryout failure is another critical mode that involves the concrete surrounding the anchor being pushed outwards as shear forces are applied. This typically happens when the anchor is placed too close to the edge of the concrete or if the concrete is not sufficiently strong to resist the applied shear load.

Concrete breakout failure involves a scenario where chunks of concrete start to break away from the main structure around the anchor due to excessive loads. This mode specifically pertains to the integrity of the concrete itself and the anchorage system's design, ensuring that there is enough concrete strength and thickness to withstand the shear forces.

By identifying these three failure modes, the answer encompasses a comprehensive understanding of how shear loading can impact