Large-scale impact tests with reinforced concrete plates for impact safety

This study investigates the impact resistance of reinforced concrete structures under extreme loading conditions, with a particular focus on scenarios relevant to the safety of nuclear power plants. Since airplane crashes have been a critical design consideration since 1977, understanding the structural response of reinforced concrete under high-velocity impact is essential for ensuring safety and resilience. Large-scale impact tests are limited in availability and have been conducted infrequently, but they provide valuable insights that complement small-scale laboratory experiments, allowing researchers to validate scaling laws and improve predictive models. This research, conducted as part of a collaboration between Technische Universität Dresden (TUD/IMB) and the Bundesanstalt für Materialforschung und -prüfung (BAM), aims to bridge the gap between laboratory-scale experiments and real-world structural performance. The experimental setup involved reinforced concrete plates (3.0 m × 3.0 m × 0.4 m) tested in a four-point supported test setup under hard impact loading using a gravity-driven drop tower. A cylindrical steel impactor (404 kg) was released from a height of 9.5 m, achieving an impact velocity of about 13.6 m/s. The study employed high-precision measurement techniques, including load cells, accelerometers, triangulation lasers, and high-speed cameras with digital image correlation (DIC), to capture force, deformation, and failure characteristics. The results indicate a distinct progression of force transmission and deformation, with localized damage characterized by global deformation, a breakout cone and scabbing at the bottom surface of the plate. 3D laser scanning is used to document the outer damage pattern and create a digital image of the specimen after impact event. The experimental data confirmed a significant transfer of impact energy, leading to plastic deformations and possible reinforcement yielding. The findings contribute to a growing database for validating numerical models and refining impact-resistant design strategies for critical infrastructure, such as nuclear power plants. The test results will be further consolidated with additional tests in subsequent publications.