on extending the concept of double negativity to shear wave
Date Issued
2009
Date
2009
Author(s)
Huang, Yuan-lei
Abstract
In this paper, we use the characteristic of double negativity to the shear building, isolating it from shear wave. We use the method of dynamics and wave propagations and solve the shear building model. We considered every one floor as a unit and build a inner manmade structure into each unit floor. As the frequency of coming shear wave close to(up to) the local frequency of inner structure brings about the locally resonance, the mass (modulus) of shear building becomes negative. The phenomena keeps the elastic wave from passing through the negative mass(modulus) medium and ensures buildings sustain the shock of waves. We use the mass-in-mass and the equivalent models, calculating the equivalent building mass of each unit by solving the equation of motion. However, the range of arising negative effective mass is related to the mass of inner structure. The equivalent model with effective mass can be represented by one-dimensional elastic solid with a unit cross section, having almost the same dispersive relation and consequences with the discrete mass-in-mass model. o no matter discussing on structure material or wave propagation of the shear building, we get negative effective mass(density) or negative effective modulus. However, it should be either both positive mass (density) and modulus or both negative mass (density) and modulus. That is “double negativity”. The material of double negativity makes the energy and propagating of wave point in the opposite direction, so the material act like a reflector. We expect it can be put into practice on the seismic engineering.
Subjects
double negavitity
locally resonance
equivalent model
seismic engineering
Type
thesis
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