Collaborative Use of DEM and FEM for Brick Joint Splitting in Strong Earthquake Ground Motion

Abstract

Masonry structures constructed about one hundred and fifty years ago, in the era of the opening of Japan, have been recognized as industrial heritages. Many of them are masonry warehouses made of brick or stone walls framed by wood members. In this research, a two-story warehouse in Tomioka city, a mortar jointed brick masonry with wooden frame reinforcements, was studied for strong earthquake ground motion. Several vibration modes were identified by micro-tremor observations and excitation tests. The three-dimensional FE overall model was constructed and tuned for the distinctive vibration modes. Two DEM local models, one for bending at the center bottom of the wall treated by plane strain, and the other for shear at the upper corner of the wall by plane stress, were constructed to evaluate brick joint splitting. For both models, dynamic displacement response obtained by the three- dimensional FEM were specified at their peripheries via periphery blocks. At the center bottom of the wall, horizontally developing joint splitting in the section was evaluated. At the upper corners, obliquely proceeding joint splitting on the wall was evaluated. In these analyses, the specified displacements were calculated by the FE model for intact brick walls, regardless of the degrading status of the walls. Although this assumption will have to be justified, the results of DEM were consistent with the reported summary of past earthquake damages.

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References

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