Direct Analysis for Design Evaluation of Partially Restrained Steel Framing Systems

Abstract

The commentary to the AISC-LRFD Specification addresses the design of framing systems containing partially restrained (PR) connections, but it does not provide specific guidance on how to analyze these types of systems to determine appropriate internal forces for design. In addition, it provides little information on how to select an appropriate connection stiffnesses for design calculations, such as the calculation of effective length factors. This paper presents an approach that allows for the consideration of nonlinear connection response using commonly available elastic analysis software. In addition, the application of the direct analysis approach to PR framing systems is presented in the context of the proposed method for handling the connection nonlinearity. The direct analysis approach allows for stability to be assessed using the AISC-LRFD beam-column interaction equations with the axial strength term Pn determined based on the actual member length. This eliminates the complexity of determining effective length factors for partially restrained framing.