When a truck impacts on a reinforced concrete (RC) column such as a bridge pier at a high velocity, a large reaction force would generate which would damage the truck, hurt the passengers and destroy the column. Lightweight foams with excellent energy absorbing performance are often used as safeguard constructions to resist impact. The impact behavior can be divided into soft and hard impact. In the case of soft impact, the impacted structure deformation is predominant. In the paper, metallic foam safeguarded RC square columns impacted by a rigid block are simulated using the ABAQUS code software, and the influential characteristic of foam density on the peak impact force and ultimate energy absorption is focused on. The simulated results indicate that the foam safeguard constructions play remarkable role on impact resistance. It is exciting that there appears almost an identical critical foam density corresponding to the minimum peak force and the ultimate energy absorption, which is of great significance for engineering design of this type of safeguard constructions to resist impact.

The growth in high-rise building construction has increased the need for hybrid reinforced concrete and steel structural systems. Columns in buildings are the most important elements because of their seismic resistance. Reinforced concrete (RC) columns and steel columns were used herein to form hybrid structural systems combining their distinct advantages. Eleven 3D building models subjected to earthquake excitation with reinforced concrete beams and slabs of 12 floors in height and with different distributions of mixed columns were analyzed by the SAP2000 software in order to investigate the most suitable distributions of a combination of reinforced concrete and steel columns. Top displacements and accelerations, base normal forces, base shear forces, and base bending moments were computed to evaluate the selected hybrid structural systems. The findings are helpful in evaluating the efficiency of the examined hybrid high-rise buildings in resisting earthquakes.