Effect of the End‐Connection Stiffness on the Compressive Behavior of Modular Steel Columns

Abstract

This study investigates the axial compressive behavior of tubular columns in modular steel structures, focusing on shear‐keyed inter‐modular connections (IMCs). Compression tests were first conducted on traditional steel columns and tubular members without end connections, followed by tests on four modular steel columns with and without shear‐keyed IMCs. The effects of shear‐key thickness and height were examined. The results show that, unlike traditional columns which mainly exhibited local and global buckling, modular columns with shear keys developed improved buckling resistance and characteristic S‐shaped local buckling patterns. The shear keys also effectively restrained global buckling. A refined three‐dimensional finite element model was developed and validated to assess the effects of connection parameters. Comparisons with EC3, AISC360‐16, CSA S16, GB50017, and the Li et al. model showed that existing design equations may overestimate the ultimate compressive resistance and critical buckling load of modular columns. Therefore, modified prediction equations for current design standards and a new buckling‐load equation considering end‐connection stiffness were proposed. The findings provide a more accurate and conservative basis for designing modular steel columns.