Multiple Bolt Anchorages: Method for Determining the Effective Projected Area of Overlapping Stress Cones

To determine the resistance concrete offers to tensile pullout, the concept of the stress cone has been developed. When a tensile load is applied to an anchor bolt, failure may occur by pulling out a cone of concrete which radiates outward from the embedded head to the surface of the concrete. The internal angle of the cones apex is approximately 90 degrees. The calculation of the concretes resistance to pull-out is accomplished by applying a nominal concrete stress to the horizontal projected area of the potential failure cone.