Predictive equations for the capacity reduction of CFS screwed and bolted connections at elevated temperatures

Screwed and bolted connections have been popularly used for cold-formed steel (CFS) structures. The tilting and/or bearing behaviours and capacities of these connections at ambient and elevated temperatures have been well investigated by many former research studies. However, suitable equations for predicting the reduction of the tilting and/or bearing capacities of these connections with increasing temperatures are still lacked. In this study, test results of CFS screwed and bolted con- nections at elevated temperatures obtained from some earlier research studies and a study recently conducted by the authors were summarised. Limitations of the predictive equations for the capacity reduction with increasing temperatures used in the earlier research studies were also discussed here. Later, consistent equations for predicting the capacity reduc- tion of CFS screwed and bolted connections failing by tilting and/or bearing at elevated temperatures were proposed. This study showed that the proposed equations could reliably predict the capacity reduction rate with increasing temperatures of the mentioned connections.The authors wish to thank QUT, Australian Research Coun- cil (Grant Number LP170100951), National Association of Steel Framed Housing (NASH), Building 4.0 CRC and Stoddart Group for providing financial support and research facilities. They also appreciate the valuable technical guid- ance and support provided by NASH Executive Director Ken Watson, and NASH Standards Committee members to this research study. They also wish to thank Dr. Mahenthirarasa Rokilan from QUT for sharing his knowledge on the elevated temperature material properties of CFS