MODIFIED FORMULA FOR CALCULATING ELASTIC STIFFNESS OF PANEL ZONE IN H-SHAPED BEAM-COLUMN CONNECTIONS

The elastic stiffness of the panel zone in H-shaped beam-column connections subjected to unbalanced beam moments is studied. The components of panel zone deformation are investigated. Based on reasonable assumptions, both the upper limit of elastic stiffness, which only considers the pure shear deformation of the panel zone, and the modified formula, which also includes the contribution of bi-directional flexure, are theoretically derived. Based on the verified finite element model, parametric analyses of beam-column sub-assemblages with different combinations of geometric configurations are conducted, and the other modified formula is derived from numerical fitting and is believed to have to some extent corrected errors caused by those assumptions during the theoretical derivation. The proposed modified formulas are validated through comparisons with both experimental and FEM results and found to be more accurate when compared to previous approaches.