03.24: Compressive strength of transverse and longitudinal T‐type branch plate‐to‐circular hollow section connections

ABSTRACT Connections have a great influence on the structural behaviour and safety of steel structures, hence extensive investigation has been conducted to determine the most efficient methods to design these elements. Nevertheless, for plate‐to‐circular hollow section connections the studies are mostly based on numerical technics and experimentation, this paper addresses a theoretical approach to estimate the ultimate strength for both transverse and longitudinal T‐type plate‐to‐chord connections loaded under branch plate compression. In the current work, an ultimate strength equation for each type of connection was derived using the upper bound theorem of plastic collapse, this theorem was employed to develop a mechanical model that defines the elastoplastic collapse of the connection components which is characterized mainly by the formation of yield lines in the chord. The model takes into consideration both the most influential geometrical parameters and that of membrane effects, particularly, the parameter for the effective branch member depth‐to‐chord diameter ratio of the connection was calibrated by regression analysis. Theoretical predictions were compared with available experimental data, finite element results and current design equations included in the CIDECT rules, showing fair correlation considering that the nature of some of the variables in the model proposed rely on the use of regression analysis.