Topology Optimization of Wave Barriers for Mitigation of Vertical Component of Seismic Ground Motions

ABSTRACT Vertical vibration of structures due to strong near-field earthquakes could culminate in catastrophic consequences. In this article, the optimum patterns of two types of wave barriers with different geometry configurations, buried in the soil domain, are obtained in order to reduce the vertical acceleration of the top of a circular foundation placed on the soil surface. In order to look into the influence of various soil deposits, six soil deposits with diverse material properties and bedrock depths are examined. The topology optimization procedure for finding the optimum position of the wave barriers has been conducted using coupled finite element-genetic algorithm methodology. First, the optimum layouts of the wave barriers are explored in the frequency domain, and then the efficacy of the resulted patterns has been investigated in the time domain by imposing three time history ground motions with various frequency contents at the base of the soil deposit. The results demonstrate that the optimum patterns of the stiff wave barriers could mitigate the foundation peak vertical acceleration as much as 65%. Moreover, three different structures, three-, nine- and twenty-story buildings, are chosen to examine the influence of the obtained optimized medium for the attenuation of the vertical vibration. It is deduced that by inserting the optimized layouts of wave barriers in the ground, vertical acceleration of the roof and axial force of the interior columns could be reduced to the extent of 33–86% and 21–93%, respectively. In the last part of the study, the effects of WBs on reduction of vibrations inducing by both shear and compressional waves are investigated.

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