內部磚牆對RC建築物喪失底層柱之彈塑性反應影響評估

Evaluation for the Effect of Interior Brick Infills on the Elasto-plastic Response of an RC Building Subjected to Column Removal

當建築物的底層柱遭受到外力破壞喪失支撐力時，可能會引發整體或大規模的漸進式崩塌反應。本文採用一棟10 層樓耐震RC 建築，以兩種等值斜撐模型模擬隔間磚牆的受力行為，依移除柱的位置，考量不同磚牆配置，進行線性靜力及非線性靜力分析，探討磚牆對喪失底層柱之垂直向彈塑性反應的影響。分析結果顯示，當磚牆配置於較短跨徑之主梁時，較能降低梁端彎矩需求容量比；由含牆構架的垂直載重-位移曲線得知，磚牆只在構架初始降伏階段有較為明顯之強度貢獻，對整體結構之極限垂直崩塌強度提升效果不大。磚牆產生脆性破壞後，垂直載重將仍由梁柱構架承受。故於工程實務上，忽略RC 耐震建築物隔間磚牆之強度及勁度，可得到合理且保守之漸進式崩塌評估結果。

Progressive collapse response of an RC building may be induced if one of its ground-story columns is destroyed by an abnormal loading. In this study, interior brick-infill partitions are simulated by equivalent compression struts to investigate their effect on the progressive collapse potential of an RC building. Linear and nonlinear static analyses of the column-removed building with and without brick infills are carried out. It is realized that more apparent flexural reduction may be obtained as the brick infills are placed in the shorter structural bay adjacent to the removed column. They may help to reduce the inelastic displacement response caused by column loss. However, the vertical collapse resistance of the column-removed building is not significantly influenced due to their brittle failure characteristic. For practical engineering, it may be reasonably conservative to consider the weight of brick-infill partitions in the structural analysis without accounting for their strength or stiffness.