Finite element analysis of confined high strength concrete bridge columns with opposing-spiral reinforcement

The spiral reinforcement is a very common technique used for reinforcing columns in active seismic regions due to its high ductility and high ability of energy absorption. This paper presents a nonlinear finite element analysis of high-strength concrete confined with opposing circular spiral reinforcements. The results are compared with tested scaled concrete columns made with opposing spirals under monotonic axial loads. The developed model is used to investigate the effect of spiral spacing, γ (ratio of the core diameter to the whole cross section diameter) and compressive strength on behaviour of circular spiral reinforced concrete column confined with opposing spiral reinforcements. The results of the parametric study demonstrated that for the same spacing between spirals and same strength of concrete, increasing γ will result into increasing the failure load of the column. It is also concluded that the ductility of the studied columns is not affected by changing the value of γ.