AISC Design Guide 08 : Partially Restrained Composite Connections

Partially restrained connections, referred to as PR connections in the LRFD provisions1 and Type 3 connections in the ASD provisions,2 have been permitted by the AISC Specifications since 1949. With some notable exceptions, however, this type of connection has not received widespread application in practice due both to (a) the perceived complexity of analysis required, and (b) the lack of reliable information on the moment-rotation characteristics of the connections as required by design specifications. The notable exceptions involve specific types of connections that have been demonstrated, through experience in the field and extensive analytical work,3,4 to provide equivalent response under design conditions to that of rigid connections. The Type 2 or “wind” connections allowed under the ASD provisions are a good example of this approach. In these cases the specification essentially prequalifies a simple connection under gravity loads as a rigid connection under lateral loads. In reality, of course, these connections are neither fully rigid (FR) nor simple but partially restrained (PR). The code uses this artifice to simplify the analysis and design, but requires a guaranteed rotational and strength capacity from these connections.

AISC Design Guide 07 : Industrial Buildings Roofs to Anchor Rods

AISC Design Guide 06 : Load and Resistance Factor Design of W-Shapes

Structural members comprised of steel shapes in combination with plain or reinforced concrete have been utilized by engineers for many years. Early structures simply took advantage of the protection that the concrete afforded to the steel shapes for resistance to fire and corrosion. But research on the strength of such members was conducted in the early 1900s,1 and design provisions were formulated by 1924.2 More recently, with the advent of modern composite frame construction in high rise buildings, engineers developed new rational methods to take advantage of the stiffening and strengthening effects of concrete and reinforcing bars on the capacity of encased steel shapes.