Dynamic and Residual Static Behavior of Axially Loaded RC Columns Subjected to Low-Elevation Impact Loading

Abstract

Columns can suffer heavy damage due to dynamic impact effects, which are ignored during their design. The impact effect could be a vehicle crash to columns of streetside buildings, parking garages or bridges. However, the effect of impact loading on the behavior of reinforced concrete columns has not been sufficiently studied. In this study, an experimental and numerical investigation is carried out on the impact behavior of axially loaded reinforced concrete columns. Dynamic experiments were carried out by dropping a mass from different heights to apply low-elevation impact on axially loaded, full-scale (30 × 30 × 320 cm) columns. After evaluating the performance of the columns under varied impact loadings, the residual load carrying capacities of the columns were also obtained by static loading. Additionally, a three-dimensional finite element model was developed and validated by using drop weight experimental results. The effect of increasing the impact energy on the behavior of RC columns was also examined numerically. As a result of the research, it has been observed that, as the applied impact energy increases, the dynamic damage/failure mode changes from flexure to shear. When a column was impacted by 75.8% of its total impact energy capacity, a decrease of 38.1% in its stiffness and a decrease of 49.7% in its load carrying capacity were determined compared to its previous unimpacted state. Additionally, the static energy dissipation capacity loss of the column was reached, up to 81.7% of its preloading state. The developed finite element model can also be utilized to determine the dynamic performance and the damage modes of columns under vehicle collision-type low-elevation impacts, which can be a guide for structural engineers in the design of such vulnerable columns and will contribute to safer structural designs.