Lateral cyclic response sensitivity of rectangular bridge piers confined with UHPFRC tube using fractional factorial design

•Precast UHPFRC tube is used to enhance the seismic resistance capacity of RC piers.•Effect of the main factors and interactions is assessed using sensitivity analysis.•A fractional factorial analysis is considered with ten different factors.•Significant level of each factor is identified using the contribution and p-value.•Predictive equations for each response are developed using regression analysis. Through the use of ultra-high performance fiber reinforced concrete (UHPFRC) tubes in an RC bridge pier, the pier can substantially reduce seismic damages during earthquakes compared to the conventional RC piers. The seismic behavior of such a novel bridge pier is affected by various design factors. This study aims at identifying the significant levels of each main factor and their interactions which affect the cyclic response of UHPFRC tube-confined pier. A fractional factorial design methodology is used to statistically estimate the effects of different main factors and their interactions. 3D finite element models of the UHPFRC tube-confined columns are first generated and validated by using experimental results. Then, a sensitivity study is conducted considering ten potential material and geometry-related factors. Five response variables, i.e. the initial stiffness, load-carrying capacity, residual drift, hysteretic energy dissipation, and equivalent viscous damping, for the UHPFRC tube-confined column are examined. From the parametric study, the significant factors including the main factors and their interactions are determined for each response variable. According to the sensitivity analysis results, predictive equations are proposed to predict the response quantities for other UHPFRC tube-confined columns with the same column cross-section through regression analysis. Results demonstrate that the longitudinal steel reinforcement ratio, axial load ratio, and aspect ratio have large effects (with total contributions greater than 40%) on all the response variables.