Protection of structures subject to seismic and mechanical vibrations using periodical networks

The concept of frequency gaps in phononic crystals is widely used in physics. The feasibility and efficiency of applying this principle in damping out seismic and mechanical induced vibrations in real scale of civil engineering constructions are presented in this article through the results obtained from numerical modeling and analysis of a concrete substratum embedding steel elements (pillars) coated in a polyvinyl chloride polymer (PVC). The first configuration having the elements fully embedded into the substrate resulted in two narrow band gaps at relatively high frequencies; and when only the metallic pillars are emerging from the substrate, the band gaps shift towards the low frequencies. The results are improved and show the existence of three band gaps at medium frequencies ranging from 80 to 200 m/s when both the pillars and the polymer are emerging from the foundation. Exploring other metal-polymer pairs of materials such as "steel-rubber", "steel-silicone"," lead-rubber" and "lead-silicone", shows that a range of band gaps has shifted again towards the lower frequencies which cover part of the seismic frequency domain. Further improvement is obtained by notching the ends of the substrate in order to widen and lower the band gaps especially for "metal-rubber" pairs. For the couple of materials "steel-silicone", the width of band gap is expanded as the thickness of silicone layer is decreased from 10 to 5 and to 2.5 cm. These results show the potential of using periodic networks to mitigate seismic and mechanical vibration effects on large scale structures and components.