Fractional factorial design model for seismic performance of RC bridge piers retrofitted with steel-reinforced polymer composites

Abstract

This study explores the effects of key design parameters on the performance of seismically deficient rectangular cross-section reinforced concrete (RC) bridge piers strengthened with steel-reinforced polymer (SRP) composites. Nonlinear response of bridge piers was modeled using fiber-based section discretization. Three-level fractional factorial design of experiments at 5% significance level was used to capture the effects of design parameters and their interactions, including concrete compressive strength, yield strength of steel bars, geometric ratio of longitudinal bars, internal transverse reinforcement spacing, pier aspect ratio, and number of retrofitting SRP layers. A parametric study was used to examine the main influence of and interactions between these factors on the seismic performance of SRP-strengthened piers at different damage limit states, including concrete core crushing, longitudinal reinforcement yielding and buckling, and ductility performance. Results show that the lateral load-carrying capacity and ductility performance of SRP-confined RC bridge piers were significantly influenced by the pier aspect ratio, materials properties, and amount of transverse and longitudinal reinforcement. Moreover, the resistance to buckling base shear, and overall ductility increased with increasing number of SRP layers.