Numerical comparative analysis of second order effects of recycled aggregate concrete columns

The use of recycled aggregate concrete (from construction and demolition wastes) in buildings has the advantage of being more environmentally-friendly. However, this type of concrete has lower mechanical performance, namely in terms of modulus of elasticity. This lower value has influence on columns second order effects. For this reason, a numerical sensitivity analysis was carried out to study the influence of second order effects on safety of recycled aggregate concrete columns. Two different Eurocode 2 methods were used for this comparison: a method based on nominal curvature and a method based on nominal stiffness. The results were obtained for different slenderness values and axial force levels, for the same initial percentage of reinforcing steel area, which was determined to guarantee the structural safety due to first order effects only. The obtained results show an increase of reinforcement area in columns built with recycled aggregate concrete, when compared to natural aggregate concrete, due to second order effects.