幾何初始缺陷對具深寬翼鋼柱之抗彎矩鋼構架其耐震崩塌性能之影響

Effect of geometric initial imperfections on seismic collapse capacity of steel special moment frames with deep columns

10.6849/SE.202012_35(4).0003

張廷晧(Ting-Hao Chang)；吳東諭(Tung-Yu Wu)

初始缺陷 ； 鋼結構 ； 抗彎矩構架 ； 地震工程 ； 崩塌性能 ； Geometric initial imperfections ； steel special moment frames ； seismic collapse capacity

結構工程

35卷4期（2020 / 12 / 01）

37 - 56

繁體中文

熱軋型鋼由於軋制、運輸及安裝過程等影響，必定會存在初始變形，然而，幾何初始缺陷對特殊抗彎矩構架崩塌性能之影響，卻仍無詳細之研究或探討。因此，本研究以有限元素模擬，探討初始幾何缺陷對具深寬翼鋼柱之四層樓及八層樓之特殊抗彎矩構架其耐震崩塌性能之影響。模擬結果顯示，不同初始幾何缺陷的施加可改變鋼柱之挫曲行為，但對抗彎矩構架崩塌行為之效應於不同地震歷時下並無一致性。對於四層樓且軸力小之構架，初始幾何缺陷因構架在不同地震歷時下之崩塌模式不同，對崩塌性能之影響較不顯著；對於八層樓構架與軸力大之四層樓構架，因鋼柱挫曲於不同地震歷時下之行為較一致，因此初始幾何缺陷對構架崩塌性能影響較為明顯。然而平均而言，以挫曲模態疊加法所建立之初始缺陷，因其對崩塌性能之影響不大且可能會帶來正面影響，加上使用高擬真及高精度之有限元素模擬時，構件在加載初期即可生成初始缺陷，故建議以高精度之模擬探討構架於地震歷時下之崩塌行為時，可忽略初始幾何缺陷之效應。

Although wide-flange (W-shape) steel members are known to have initial geometric imperfections (IGIs) due to fabrication and installation, the effect of IGIs on seismic behavior of steel special moment frames (SMFs) is still not well understood. To address this shortcoming, seismic collapse capacity of 4-story and 8-story prototype SMFs with various types of IGIs is computationally evaluated to quantify the effect of IGIs created by combining buckling shapes. The results show that even though IGIs can affect column buckling behavior and frame collapse mode under certain conditions, their effect on seismic collapse capacity is generally small and inconsistent. Their influence also greatly depends on the directions of applied IGIs and column buckling shapes and may be positive if the directions are misaligned. As a result, it is suggested that initial geometric imperfections need not be incorporated in high fidelity numerical models with high precision, which can generate their own IGIs when loaded.

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