Abstract
Dynamic impact load has an extensive application area in civil engineering, including highway, military, and marine structures. Many researchers have studied the performance of reinforced concrete (RC) columns under impact load. However, very limited work has been conducted on the effect of bundle reinforced concrete (BRC) columns subjected to lateral impact load. In this study, to examine the behavior of RC columns under impact load, numerical simulations of one with normal reinforcement distribution and three different bundles of reinforced concrete column specimens have been conducted using an explicit finite element (FE) analysis. In addition to the bundle reinforcement distribution, the parameters considered in the study are impact scenarios, impact velocity, pure axial load, and impact locations. From the numerical analysis, it has been found that bundling of longitudinal reinforcement does not only improve the impact capacity but also stabilizes the fluctuating response of impacted reinforced concrete columns. Both peak impact force and maximum lateral displacements of impacted BRC columns increase with increasing initial impact velocity. The numerical results also show that pure axial load slightly improved the impact capacity of the BRC columns. Finally, while the global failure of the RC column governs the response of repeatedly impacted BRC columns, failure characteristics of the single impacted columns are associated with local concrete damage at the impact zone.
Highlights
Introduction e axial load behaviors of the reinforced concrete (RC) column have been widely studied under static loads
As the number of stories in high-rise buildings increases, the total load that is transferred to the RC column increases. is results in a large amount of steel reinforcement bar to be provided based on the design requirements which led to congested steel reinforcement bar distribution
There are mainly two options to overcome these difficulties: (a) increase the cross-sectional area of the structural element (i.e., RC column) and/or the size of the reinforcement bar, and (b) bundle the longitudinal reinforcement bars into groups of two, three, or four bars. e first option increases the total cost of the project, and it is not feasible from the standpoint of space and aesthetic requirements
Summary
E accuracy of the numerical modeling is validated by using previous experimental tests conducted by Sha and Hong [14] During their test, impact load was increased continuously by elevating the pendulum impact ring with an increment of five degrees in each subsequent impact condition until the specimen failed. In each BRC column, reinforcement bars with diameters of 20 mm, 8 mm, and 6 mm were employed for longitudinal, shear stirrup, and bundle stirrup reinforcements, respectively. During the FE simulation, the impact velocities, axial loads, and impact locations are considered for each bundle reinforced column separately.
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