Seismic shear strength of hollow-core composite bridge columns

The shear behaviour of hollow-core composite short bridge columns under nonlinear static analysis is presented in this study. The investigated composite columns comprised a concrete wall between two concentric circular tubes, an outer circular fibre-reinforced polymer (FRP), and an inner steel tube to form hollow-core FRP-concrete-steel (HC-FCS) columns. Solid three-dimensional numerical models were developed and validated against experimental results. The models subsequently were used to conduct a parametric finite element study by performing a nonlinear static analysis on the shear behaviour of the HC-FCS short columns under combined axial and lateral loadings. The investigated parameters are the effects of the column aspect ratio, steel tube width-to-thickness ratio, confinement ratio, concrete wall thickness, applied axial load level, and column concrete strength. This study revealed that the shear behaviour of HC-FCS short columns is close to an extent to the behaviours of reinforced concrete columns. A comparison between the attained shear strengths and the existing analytical models in the literature was carried out. A critical assessment of these shear strength models revealed vast differences in predicted responses. Finally, a new expression is proposed to predict the shear strength of HC-FCS columns under seismic loads for design purposes and real-life applications.