Cantilever and Suspended Span Roof Framing System

AISC has proposed an alternative to the use of joist girders. That proposal is based on a system that was originally developed for bridge structures. The concept was first applied to architectural structures many years ago, but was abandoned for several reasons. One principle reason for this was the system's dependence on artificial loads to balance the presence of real loads. Because of this, the system may be very susceptible to overload. The use of the Gerber System will produce a structure that is nearly half the depth of a Joist Girder System. That should be the primary reason for choosing to use the Gerber System. This paper proposes a design approach that allows this system to be used with confidence and safety. The proposed approach is based on a stiffness analysis instead of a strength analysis. The purpose of this paper is to encourage the safe use of the Gerber Framing System.