## 1 Introduction  
Structural elements nowadays face the possibility of being subjected to sudden dynamic load in addition to the design static load, which can lead to catastrophic failure of the structure. This type of unusual dynamic load can be caused by falling objects, vehicular impact, or explosions. These incidents may occur accidentally or intentionally as a result of terrorist activities. Columns on the ground floor and parking garages are potentially exposed to such dynamic load caused by vehicular impact [1, 2]. In recent years, column damage or even column failure due to vehicle impact has increased due to the increase in vehicles and traffic load as a result of population growth and urbanization [2, 3, 4, 5]. Vehicle accidents with the front columns of roadside buildings and columns in parking garages are likely to occur unexpectedly, resulting in significant dynamic loads [6]. Some examples of column failure and damage due to car impact are shown in Figure 1[7]. Most of the previous studies have focused on the impact behavior of RC beams and slabs under impact loads [8, 9, 10, 11, 12, 13]. Some studies were dedicated to investigating the impact and blast behavior of RC structures retrofitted with different types of fiber-reinforced polymer (FRP) [14, 15, 16, 17, 18, 19]. It was found that the FRP jacket enhanced the performance of RC structures under blast load. Limited studies are available on the impact behavior of axially loaded retrofitted RC columns under impact load [1; 2; 20]. In particular, there is a scarcity of information in the literature about the detailed behavior of a retrofitted RC column under vehicle impact. Therefore, it is necessary to study systematically the behavior of RC columns subjected to different types of car impact and to develop a protective system that can prevent any type of damage to the column during accidental low-velocity car impact. One of the objectives of this study is to categorize the behavior of RC columns under vehicle impact numerically. The abnormal collision of a road vehicle with a column can cause the affected columns to lose a significant amount of strength. As a result, the column may be unable to carry the loads that have been applied to it [21]. A number of codes and industry standards are concerned more about the capabilities of the designed structures to resist impact and blast loading. Most of the current codes of practice [22] recommended the use of equivalent static forces to account for anticipated lateral impact forces in column design, particularly for building columns located near roads or in parking garages. However, there is a wide range of variation in the values of equivalent static forces derived from different codes of practices, as shown by [PERSON] et al. [5; 23]. Furthermore, it is shown in many studies [24; 25; 26] that the equivalent static forces recommended by Eurocode 1 for designing columns against transverse impact loads do not provide sufficient protection for the columns in the event of a collision between a veered vehicle and a specific column, particularly for a large column. Many research centers and institutes have tried to develop the optimal columns' protective systems [27]. However, after an intensive search, it was found that most of the protective systems developed and made available in the market are dedicated to protecting the columns located in warehouses where only forklifts are permitted to access and the speed limit is below 10 km/h. Only a few studies have been conducted to investigate the use of honeycomb sandwich panels to protect bridge piers and steel columns from vehicular impact [28; 29]. The energy absorption capability of the honeycomb sandwich panels determines the efficiency of column protection. Furthermore, if the sandwich panel is damaged in a car collision, it should be replaced with a new sandwich panel.