Study On Design And Properties Of Seismic Metamaterials

The earthquake has caused catastrophic damage to humans,and this damage is usually caused by the collapse of buildings.Therefore,strengthening the seismic capacity of buildings has become the most urgent concern for construction engineers and related researchers.At present,the traditional seismic technology has a weak ability to attenuate the vertical seismic energy,and the problem of excessive moving distance of the plane cannot be ignored.Recently,seismic metamaterials in the field of physics have opened up a new way to fight earthquakes.Seismic metamaterials can greatly attenuate and control the propagation of seismic waves in the corresponding frequency range of the band gap by utilizing the band gap characteristics.In this paper,the seismic surface wave,which is the most concerned about seismic research,is taken as the research object.The numerical simulation and model test method are used to design the seismic metamaterial and verify its effectiveness.The main research contents are as follows:(1)A seismic metamaterial based on a square cylinder is proposed,which not only has a good attenuation effect on seismic Lamb waves,but also has a good attenuation effect on surface waves.(2)According to the column structure,the band gap of the metamaterial is related to the geometric parameters of the structural unit.By changing the aspect ratio and the moment of inertia of the column structure to adjust the position of the bands,an I-shaped seismic metamaterial is designed to achieve a wider band gap.(3)Aiming at the problem of narrow band gap of seismic metamaterials of resonance type,a wide-band gap seismic metamaterial is designed by introducing H-shaped fractal structure unit.The structure utilizes the self-similar characteristics of the fractal structure to achieve a plurality of band gaps,thereby extending the wide band gap.The band structure and transmission spectrum are analyzed in detail.The results show that when the order of the fractal structure is increased,a wider total band gap width,more resonant modes and more band gaps can be obtained.(4)Introducing the Matryoshka structure unit and designing a wide band gap seismic metamaterial.It was found that when the number of Matryoshka is increased,a wider total band gap width,more resonant modes,and more band gaps can be obtained.And the structure of the Matryoshka is simple and easy to implement.(5)Designing a seismic metamaterial plate,which is a two-dimensional composite material consisting of a steel block wrapped in a rubber plate according to the square lattice period.Through numerical analysis and a 1:30 model test,we found that this plate-shaped seismic metamaterial can well attenuate surface wave in the low frequency and has a relative band gap width close to 100%.In a word,in the face of the difficulties encountered in earthquake prevention and disaster reduction of buildings,this paper combines the latest research hotspot “metamaterials” in physics to design models and achieve effective attenuation of seismic waves.The research on seismic metamaterials not only provides theoretical guidance and reference for building earthquake resistance,but also promotes the research of metamaterial in elastic waves.