Ultra-high performance concrete-filled dual steel tubular slender columns subjected to eccentric loads
Vicente Albero, Carmen Ibáñez, Ana Piquer, David Hernández‐Figueirido
Abstract
This paper experimentally investigates slender ultra-high performance concrete-filled dual steel tubular (UHPCFDST) columns under eccentric axial loading. Four typologies were tested: double-skin (DS), double-tube (DT), and single-tube columns as reference (OT, IT). All tested columns exhibited ductile behaviour, with global flexural buckling as the dominant failure mode. The UHPC-DT column achieved the highest absolute axial load, but the UHPC-DS configuration showed superior relative efficiency due to its lower slenderness. Compared to normal-strength concrete, UHPC specimens achieved up to 85 % higher absolute axial strength. However, their relative structural efficiency and ductility were lower. This is attributed to the fact that UHPC markedly increases the plastic axial resistance without a proportional increase in the critical buckling load, resulting in higher relative slenderness. Furthermore, the simplified design approach provided by EN 1994-1-1 was assessed through comparison with experimental data, confirming its suitability as a conservative and reliable basis for the design of UHPC-filled slender composite columns. • Tests on slender UHPC-filled dual steel tubular columns under eccentric loading • UHPC significantly increased axial capacity compared to normal-strength concrete • Relative efficiency decreased with UHPC due to increased slenderness • Despite being out of scope, EC4 predictions were conservative for UHPCFT columns • ICCR and CSCR indexes properly quantify core and composite action in column design