Essential state-of-stress features of HBBC connections revealed by modeling simulative strain energy

This study reveals the essential working features of H-beam-to-box-column (HBBC) steel connections applying structural state-of-stress theory. Firstly, a finite element convergence criterion is proposed to judge the simulative ultimate loads of the HBBC connections. Then, the state-of-stress mode and the parameter characterizing the mode are built using the simulative strain energy data. As a result, the Mann-Kendall (M-K) criterion detects the essential and inevitable working behavior feature complying with the natural law from quantitative change to qualitative change of a system, which reveals the starting point in the failure process of the HBBC connection. The failure starting point redefines the HBBC connection's failure load and its calculating formula is fitted considering three configurational parameters of angle. Referring to the failure load, the M-K criterion identifies the elastic–plastic branch (EPB) point of the HBBC connection from its state-of-stress evolution. Both failure load and EPB load provide the significant reference to the improvement on the existing design codes of connections with the rational safety margin and without the over conservation of the traditional stress capacity design load.