Resistance of nuclear power plant (NPP) civil structures against a crash of a commercial airplane is verified with numerical models or semi-empirical and analytical formulas. In order to be reliable, used models and methods have to be validated against reliable empirical data, which is scarcely available in public. Vibrations in an entire building induced by such highly dynamic impact is one of the arising phenomenon that need to be assessed in order to ensure the functionality of critical equipment and components of a NPP. In order to obtain experimental data for model validation, a series of three impact tests was carried out with a structure having a front wall, a floor and a rear wall, each being 150 mm thick. In addition to impact tests, the structure was subjected to modal testing before and after the first impact test and then after the last impact test. A soft projectile having mass of 50 kg was used in the impact tests with the impact velocities ranging between 111.2 and 116.8 m/s. In this context, a soft projectile is considered to be much more deformable than the structure that it impacts against, resembling the fuselage of an aircraft. In addition to experimental data generation, the aim of the tests was to study how the vibration propagates from the hit point, how it gets damped and how these properties change when the structure is already damaged. Propagation of vibration was measured in the tests with six displacement sensors and accelerometers, spaced along the propagation path of vibration. In addition, strains in the reinforcement were measured at ten locations. The change in response of the structure between the consecutive impacts depended on the type of quantity measured: the displacements increased somewhat from a test to the next one while the accelerations decreased in a similar manner. At the same time no clear behaviour could be identified for the reinforcement strains. In each case, the main frequencies at which the response occurred decreased slightly from a test to the next one with the frequencies being slightly lower than the ones identified in the modal analyses carried out under same conditions.
|Publication status||Published - 2015|
|Event||22nd International Conference on Structural Mechanics in Reactor Technology 2013, SMiRT 22 - San Francisco, United States|
Duration: 18 Aug 2013 → 23 Aug 2013
Conference number: 23
|Conference||22nd International Conference on Structural Mechanics in Reactor Technology 2013, SMiRT 22|
|Abbreviated title||SMiRT 22|
|Period||18/08/13 → 23/08/13|
- aircraft crash
- soft impact
- impact testing
Vepsä, A., Aatola, S., Calonius, K., & Halonen, M. (2015). Impact testing of a wall-floor-wall reinforced concrete structure. Paper presented at 22nd International Conference on Structural Mechanics in Reactor Technology 2013, SMiRT 22, San Francisco, United States.