Seismic Metamaterials with Low Frequency Wide Bandgaps Using Steel Barriers

讲座名称: Seismic Metamaterials with Low Frequency Wide Bandgaps Using Steel Barriers
讲座时间: 2020-01-10
讲座人: C. W. Lim
形式:
校区: 兴庆校区
实践学分:
讲座内容: 题目:Seismic Metamaterials with Low Frequency Wide Bandgaps Using Steel Barriers 报告时间:  2020年1月10日(星期五)上午10:30- 12:00 报告地点:航天学院 第四会议室 报告人:C. W. Lim 报告摘要: The feasibility of built-up steel section as barriers of seismic metamaterials is proposed in this study.  We consider two types of built-up steel sections (as resonators) and the surface waves propagation in a single layer homogenous medium and a six-layered soil medium (substrate) is investigated by analytical and computational techniques.  The presence of resonator on the surface of a semi-infinite substrate results in the generation of local resonance that induces low frequency wide bandgaps.  The generation of local resonance bandgaps are mainly governed by the impedance mismatch between resonator and substrate and the coupling of surface waves propagating on the surface of a semi-infinite substrate with a longitudinal mode of resonator.  We further consider the surface waves propagation in both types of media and compared the bandgap frequencies.  For layered soil media, a bandgap with relative bandwidth greater than 1.5 is reported that indicates the surface wave bandgap is relatively wide and it is located at a low frequency.  The result also shows the effect of impedance mismatch on the bandgap width.  Furthermore, with a change in geometric parameter of the resonator and material properties of substrate, the position and width of bandgap do vary.  The infinite unit cell model study is further validated by a finite unit cell based frequency response and time transient analyses.  An excellent agreement is observed.  The time transient analysis results indicate more than 50% reduction in vibration amplitude of the surface waves.  The study provides an insight for having steel piles to protect critical infrastructures from earthquake hazards..
相关视频