冷軋I型斷面格柵梁樓板之結構強度與行為

The Structural Strength and Behavior of Steel Framing Floor Using Cold-Formed I-Shaped Joists

文楚雲(Chu-Yun Wen)

指導教授 ： 潘吉齡

朝陽科技大學/理工學院/營建工程系/碩士(2017年)

摘要

本研究將針對一體成形冷軋I型格柵梁與外覆材結合之樓板進行四點載重撓曲實驗，另外有測試格柵梁樓板與立柱接合實驗，以符合實際輕型鋼構建築之接合方式，試體的主要分別有純框架樓板以及翼板貼附大小片尺寸的外覆材型式之樓板，且為了提高樓板承載力，使用腹板加勁材之方式以防止支承處腹板挫屈之行為。亦嘗試透過轉換斷面法進行AISI規範之運算結果與實驗值互相比較。本研究另使用ABAQUS有限元素分析軟體，建立試體模型、材料性質、拘束條件、載重方式、邊界條件與網格設定，分析所得之結果來比較兩者之差異性，包含力與位移曲線、破壞模式及結構勁度。
實驗結果發現翼板貼覆外覆材或腹板有加勁材的試體極限承載力明顯高於翼板無貼附外覆材或腹板無加勁材的試體，另外若翼板貼附的外覆材尺寸較小，則在承壓處下方的力量傳遞上，會有應力較集中之行為，所以外覆材尺寸較大則試體的承載力會有所提高。透過轉換斷面法及AISI規範計算實驗試體之翼板應力並與實驗值比較，結果證明轉換斷面法之運算方式以及AISI規範計算是可行的。
試體模型分析結果，可預測此格柵梁樓板在彈性階段之結構勁度以及受載重後產生應力集中之位置，而研究發現有限元素模型與實驗試體的力與位移曲線仍有些差距，其中因素可能為試體因組裝或運送而導致翼板兩邊非水平狀態和腹板並未與翼板成垂直狀態的初始不平整因素產生，而影響實驗試體的整體承載力。

關鍵字

冷軋型鋼 ； 鋼框架樓板 ； I型格柵梁 ； 撓曲強度

並列摘要

This research is focused on the structural strength and behavior of the integrated I-shaped joist sheathed with OSB, both experimental and analytical studies were conducted in this study. In addition, the steel framing floor assembled with wall studs was investigated in accordance with the real connecting condition. The OSB boards of both smaller size and regular size were also utilized in the test specimens to study the differences of structural strength. All specimens were assembled with blocking sections to prevent the joists from lateral buckling. The finite element analytical software, ABAQUS, was adopted to establish structural model, material properties, restrain conditions, loading types, boundary conditions, and mesh formulation. The analytical results were used to compare to the tested results including load-displacement relationship, failure mode, and structural stiffness. The AISI prediction based on the concept of transformed section was also used for comparison purpose.
It was observed from test results that the ultimate strengths of the specimens sheathed with OSB or installed web stiffeners were much higher than those of the specimens without sheathing or installing web stiffeners. The phenomenon of stress concentration was found between the boards in the specimens sheathed with smaller size of OSB, therefore, the strength of specimen sheathed with smaller size of OSB was lower than the specimen sheathed with regular size of OSB. The stress of transformed section calculated based on the AISI specification has a good agreement with the stress detected from the strain gages mounted on the flange of test specimen. It seems that transformed-section method can be adopted in the computation of the structural strength of floor specimen.
By observing the structural behavior of finite element analysis, the model can be used to simulate the failure mode of specimen, and predict the stiffness of steel framing floor system in the elastic range. However, the discrepancies of ultimate strength and displacement were found between the analytical model and test specimen. It is probably due to the initial imperfection in the flange and web of joist during the time of assembly or transportation.

並列關鍵字

Cold-Formed Steel ； Steel Framing Floor ； I-Shaped Joist ； Flexural Strength

參考文獻

2.American Iron and Steel Institute (AISI), “2007 Edition of North American Specification for the Design Cold-Formed Steel Structural Members,” CANACERO,2007.

3.潘吉齡、林明毅，「冷軋I型斷面在撓曲強度上的探討」，碩士論文，朝陽科技大學營建工程系，台中，2013。

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