Elastic In-Plane Stiffness for a Circular Cut Reduced Beam Section (RBS)

One newer moment connection that has been introduced and validated (prequalified) for use in high seismic areas is the so-called "dogbone"ť, or reduced beam section (RBS). The purpose of this paper is to briefly review the basic in-plane stiffness formulation for a prismatic beam, develop more rigorously the full non-prismatic, first_order elastic stiffness changes caused by the circular RBS, provide its simplified representation, and finally conclude with the general RBS stiffness effect suggestions for design. Other RBS seismic design and performance issues of this efficient and popular detail will not be addressed, as they are already well covered in other available sources.