การวิเคราะห์กำลังการโก่งเดาะของเสาเหล็กขึ้นรูปเย็นที่มีหน้าตัดไม่ปกติภายใต้แรงอัดร่วมศูนย์โดยไฟไนต์อิลิเมนต์แบบไร้เชิงเส้น

Abstract

This paper presents a study of capacity and buckling behavior of irregular section cold-formed steel columns under concentric compressive loading by using the Finite element method (FEM). The study specimens are composed of 4 different section types with 230, 950 and 1900 mm. in length, totally 12 analysis cases. First, the finite element model was validated through an agreed behavior between corresponding test and analytical results. The analytical results show the different buckle modes depending on the length of column. The short columns exhibit local bucking or the combination with distortional buckling mode. A combination of overall flexural and torsional buckling modes can be observed for the long columns. For the intermediate columns, the buckling mode is that between the local and overall buckling modes together with distortional buckling. Regarding ultimate capacity, the calculated capacity by using AISI result under-estimation compared with those from FEM with an averaged ratio of   P_FEM/ P_AISC  about 1.074.