Experimental and analytical investigations on compressive behaviors of modular steel shear-keyed tubes

Modular construction of engineering structures use shear-keyed inter-modular connections (IMC) to support modular units' tubular columns that produce column discontinuities and complicate force transfer. This study subjected four steel shear-keyed tubes with varying shear-key heights (Lt) and thicknesses (tt) to axial compression testing. The tests revealed that the tubes' buckling resistance improved by increasing Lt and tt. Tubes failed with S-shaped inward and outward local buckling near shear-key or 1/4 or 1/2 of column height; however, shear keys mainly prevented their global buckling. The finite element model (FEM) was generated and validated to study the varying parameters' impact on various member features. The findings demonstrate that the nominal strength of the tubes was reduced to achieve compression yielding, making the EC3:1–1 class 3 slenderness limit non-conservative. Similarly, prediction equations in EC3:1–1, AISC360-16, CSA S16, and GB50017 overestimated the ultimate compressive resistance (Pu), proving them unsafe. Hence, buckling and modified prediction equations were developed, ensuring by reliability analysis that they accurately anticipated the axial compression behavior of modular steel shear-keyed tubular columns.