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Military facilities, buildings such as embassies or nuclear power plants must be
protected against effects and impacts from terrorist attacks or accidents. In the
course of new building or upgrading existing structures the protective function
against gun fire or debris due to explosions should be fulfilled with small
dimensions. The main material p...
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Citations
... To deal with these growing requirements efficiently, there is a variety of strengthening methods and approaches, e.g., (Michal, 2014;Zohrabyan et al., 2020;Zohrabyan et al., 2022). ...
... Studies by other researchers have shown that fiber-reinforced concrete layers significantly improve the resistance of reinforced concrete structures against high dynamic loads. It was found that steel fiber concrete layers reduced crater formation on the protective side by up to 95% compared to monolithic reinforced concrete structures (Michal, 2014). As the tests with UHPFRC in this paper were initial tests to explore its potential as a protective layer. ...
... As the tests with UHPFRC in this paper were initial tests to explore its potential as a protective layer. The same conditions and parameters as for the two-layered plates of (Michal, 2014) were used for this investigation. The results of this paper are consistent with the basic findings and confirm the effectiveness of UHPFRC in enhancing structural protection against high dynamic loads. ...
Recently there has been an observed change in security policy across the globe which implies that humanity must prepare for hybrid and asymmetric acts of war. This security situation will result in spontaneous attacks from non-military groups. The threats include ballistic attacks from commercially available weapons, detonation of explosives, and impact of vehicles. These attacks are focused on critical infrastructures. Reinforced concrete (RC) elements with ballistic and explosion protection are of huge relevance. This requires new concepts and innovative solutions for the protection of new buildings and/or for the strengthening of existing structures. In this paper a method for the increase of structural safety is shown using Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) or sprayed UHPFRC, so called UHPFRSC, as a surface layer for reinforced concrete structures. The UHPFRC/UHPFRSC is applied in thin layers of 30 - 80 mm on the protection side. The interaction of the two different cementitious materials results in increased resistance to high dynamic loads. The traditional reinforced concrete on the impact side absorbs a major fraction of the energy of impact. On the back side (protection side), tensile forces are generated by the impact, which can excellently be handled by the UHPFRC/UHPFRSC. For proof of concept of the hybrid strengthening method, tests were carried out on UHPFRC - RC composite elements. In the test campaign, ballistic tests were performed using test specimens with dimensions of 500 × 500 mm. The layer thicknesses were 120 mm reinforced concrete and 40 mm UHPFRC. Additional steel rebars in the UHPFRC layer were applied for half of the specimens. The investigation demonstrated the effectiveness of the strengthening method, showing high resistance to high-dynamic loads. This behavior is attributed to the absorption and transfer of tensile stresses by the UHPFRC, that reduces penetration depth and damage, ensuring remaining load-bearing capacity after gunfire.
... In the case of plates with ring mesh, it is basically possible to stop a projectile, but individual very large and many small debris are produced, which can fly far away. According to the results, it could be reconfirmed that steel fiber reinforced concrete improves the tensile strength and ductility of concrete elements and improves the resistance of concrete elements to dynamic loads [ [9]]. For panels with construction joints, there is still a need for investigation. ...
Due to an increasing threat of attacks with small arms or explosions on (government) buildings or structural facilities requiring special protection, protection against such impacts is becoming more and more important. For this reason, the Chair for Concrete Construction at the Institute of Structural Engineering at the Bundeswehr University Munich is conducting research into the improvement and development of effective structural protection systems. For this purpose, a protective layer of metal is used, which is either concreted into a steel fiber reinforced concrete slab with concrete compressive strength class of C40/50 (e.g. ring mesh) or subsequently applied to one side of the hardened slab surface (e.g. metal foam). The protective function thus achieved is validated by means of gunshot tests. Thus, in a first step, the crater ejection on the protective side, i.e. the side facing away from the bombardment, is documented. This is followed by an evaluation of the crater volume by weighing the tested specimens. The mass determined by the difference (before-after) is verified by means of a geometric control calculation.
... The plates of this mixture showed a good protective capacity and withstood the shots well. (Michal et al., 2014) -It can be said that the specimens produced with fiber Masterfiber 249 also showed good results. It has to be said, however, that the fiber MF 249 only slowed down the projectile and did not stop it. ...
