| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 90 === This study investigates the effect of vertical irregularity due to strength and stiffness on dynamic structural performance. The scope of this study includes two parts. The first part uses a two-story structural model to study the elastic dynamic performance of masonry-infilled structure. The results of this part show that both stiffness and distribution of masonry wall will affect structural dynamic characteristics and member forces. In addition to stiffness of columns, location of masonry walls, stiffness of masonry walls, and beam-to-column ratio are also important parameters for forming a soft story. It is found that the bottom story is vulnerable to become a soft story while stiffness of masonry walls and beam-to-column ratio increase.
The second part uses a two-story steel shear-beam model and a nonlinear static procedure to investigate the effect of story strength ratio and story stiffness ratio on structural displacement capacity, deformation distribution and earthquake resistant capacity; besides, reasonable definition of weak story and the influential parameter will be obtained. The results of this study show that the critical strength ratio which defines weak story is affected by material ductility, yield stiffness ratio, axial force of column, and compaction of section, thus it is not a fixed value. The ratio of story strength and shear force and the ratio of story stiffness and shear force are better indices which estimate the degree of vertical regularity than the ratio of story strength and the ratio of story stiffness. By comparing the structures which have the same strength, fundamental period, and drift capacity, it shows that the earthquake resistant capacity of structures with weak story is about 53 to 56 percent of that of structures with story strength distributed perfectly.
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