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Post-Tensioned Reinforced Concrete Columns under Impact Loading
Abstract:
Assessment of structural responses to dynamic loads, such as impact, is essential because these loads can cause severe damage to infrastructure and pose risks to human lives. Important elements of structures, like bridge piers and building columns, are particularly vulnerable to impact loads from vehicle collisions or rockfalls. To address such critical loading, we conducted impact tests to analyze the responses of post-tensioned steel-reinforced concrete (RC) column sections under controlled impact loads. A large drop tower was used to accelerate a rigid cylindrical projectile with a flat nose, having a diameter of 100 mm, a length of 380 mm and a weight of 21.6 kg. Reaction forces were measured using load cells, while accelerometers captured high dynamic accelerations during impact. Both the reinforced concrete columns and the impactor were equipped with a speckle pattern, facilitating Digital Image Correlation (DIC) analysis. The DIC system was used to track the impactor velocity, to measure deflections, and to observe of the cracking patterns on the column surfaces. In total, six 200 mm × 300 mm × 1500 mm different column specimens were tested under two distinct impact velocities: 25 m/s and 33 m/s. The clear span was 1000 mm and the longitudinal and transverse reinforcement ratios were approximately 2 % and 0.7 %, respectively. Four columns were post-tensioned to two levels of 34 % and 67 % of their axial capacity and compared to two reference specimens with no axial force. This range of axial force was chosen to have a detailed evaluation of how different levels of post-tensioning influenced structural performance, specifically in terms of reaction force, lateral deflection and cracking patterns under impact loading. We observed that the mass of debris generated by the impact increased with impact velocity. In most cases, the debris mass also increased with a higher axial force ratio. This trend is likely due to the release of elastic energy stored within the post-tensioned specimen during the impact event, which intensified the dynamic response. Specifically, we noted a pronounced spalling of the concrete cover, primarily on the rear side of the impact, which led to the exposure of the reinforcement. The results of this study can serve as basis for analytical and numerical models and as guideline for testing additional parameters in similar specimens.
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3-10
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December 2025
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