冷軋型鋼由於重量輕、價格便宜又具有足夠的強度，且可配合許多接合套件的生產，施工相當快速又可以縮短工期，近年來廣泛地應用於載重要求較低的單層或雙層建築物。對於冷軋型鋼構件而言，其斷面因屬於薄壁型鋼，在承重後易發生局部挫屈及側向挫屈而導致強度的降低，目前市面上最常使用的冷軋型鋼構件為傳統的C型鋼，但是這類傳統的C型鋼由於承載荷重的能力較低，且斷面為不對稱之開槽斷面，而傳統封閉的方管或圓管斷面雖然強度較高，但在斷面封閉時需採焊接接合，而焊接的高溫則會影響到材料的性質。本文將針對新型的機械扣夾封閉方式之H型鋼，研究其對於斷面特性及梁桿件力學行為之影響，並界定其破壞挫屈模式之臨界值及此種斷面形式之梁桿件在反覆載重下之承載行為。 根據研究中發現封閉斷面冷軋型鋼的承載力的確較高，而使用機械扣夾封閉方式，如果製作過程確實，則控制樑桿件極限強度的主要原因為構件局部挫屈或側向扭轉挫屈，並不會產生扣夾處的分離而導致強度的降低。研究中也發現冷軋型鋼構件其斷面因屬於薄壁型鋼，在承重後撓度甚大，因此在結構設計中應考慮撓度控制。而在反覆載重作用下，冷軋型鋼構件不論是在極限載重、勁度衰減及韌性等都較單點載重實驗時為低，但若在適當的設計撓度控制內則其差異並不大。 Cold-formed steel has been widely used in low rise building construction and in buildings with light to medium load. The major benefit of using cold-formed steel is the light unit weight of the section. The cold-formed steel is usually made from thin plates which results in large member plate width/thickness ratios and subsequently local and lateral torsional buckling when subjected to external loading. Furthermore, the cold-formed steel requires welding or built-up devices, such as bolts, when the member is used for construction erection. These processes induce stress concentration on bolted location or welding stress along the welds which reduces the member performance. This study is focused on the flexural behavior of a newly-developed H-shape cold-formed steel. Test results show that the sections possess approximately double symmetric axes which simplifies the design process of cold-formed steel construction. This characteristics also significantly increases the stability of such members. It is also found that the section is capable of developing plastic moment if member slenderness ratio is properly defined.
