| Advanced construction materials like ultra-high-performance concrete (UHPC) and highstrength steel (HSS) have been well recognized by the construction industry in recent years owing
to their remarkable mechanical properties, including high strength and durability. This presents a
promising advancement in structural engineering for enhancing the structural performance of
different components under extreme loads such as seismic events. However, there exist limited
experimental and numerical studies on the seismic performance of HSS-reinforced UHPC (UHPCHSS) bridge piers. Hence, this study aims to numerically investigate the seismic response of
UHPC-HSS columns based on a systematic parametric study. An OpenSees fiber-based model of
a prototype UHPC-HSS circular pier is developed and validated against experimental data from
the literature and is used to systematically vary six key parameters—aspect ratio, axial-load ratio,
UHPC compressive strength, longitudinal and transverse reinforcement ratios, and yield strength
of HSS bars. A three-level (3k) fractional factorial design of experiment (DOE) at a 5%
significance level is used to explore the main and interaction effects of these parameters on the
seismic response of UHPC-HSS columns. The findings revealed the potential of UHPC-HSS
synergy to achieve slender yet ductile piers and provide designers with evidence-based guidance
for parameter selection under seismic demands.
Keywords: UHPC, High Strength Steel (HSS), UHPC-HSS columns, Seismic performance,
Parametric study, OpenSees, Fiber-based model, Fractional Factorial Design of Experiment
(DOE), Sensitivity Analysis |