PR connections in design practice

Abstract

This chapter outlines the design of unbraced frames with partially restrained (PR) connections as practiced in an engineering design office. The feature of a computer program and a procedure designing PR frames using composite connections is presented with an example. An issue for further research to assist designers is identified, based on examples. The economic incentives for partially restrained connections in structural steel frames are found in the reduction of steel tonnage due to end restraint and in simpler and less expensive connection details. The idea is simple, that is make use of the inherent stiffness of connections that have traditionally been ignored, perhaps with minor modifications to details that enhance connection performance or improve the predictability of response. This approach is feasible for low to moderate height structures built in the United States. The use of PR frames in seismic zones is permitted; however, there is no codified design procedure. Minimum lateral forces, which are a function of system ductility and lateral stiffness are specified by code for basic prequalified systems.