Eccentric compression behavior of L-shaped column fabricated by thin-walled square steel tubes based on self-drilling screw connections

In this study, a new L-shaped column fabricated by thin-walled square steel tubes (LFTST columns) based on self-drilling screw connections is proposed. The LFTST columns consisted of square steel tubes, U-shaped parts, angle parts, gusset plates, and self-drilling screw connections. LFTST columns possess several advantages including easy transportation, rapid assembly, and eco-friendliness. Consequently, they are suitable for low-rise buildings, such as village-building, low-rise dormitories, and low-rise office buildings. However, the compression behavior of LFTST columns remains silent. Five full-scale LFTST column specimens were subjected to eccentric compression tests. The variables under consideration included eccentricity (with values of 0mm, 40mm, and 80mm), thickness (2mm and 4mm), and the number of gusset plates (0, 1, and 3). The failure modes, bearing capacity, load-displacement response, and strain development of the LFTST specimens were obtained. Subsequently, finite element (FE) models of LFTST columns were established and used to analyze the eccentric compression behavior of LFTST columns. The FE modeling results agreed well with the experimental results. A detailed parameter analysis was conducted to evaluate the effects of various factors. These factors included the thickness of the plates (2mm, 3mm, and 4mm), the width of the gusset plates (100mm, 150mm, and 200mm), limb spacing values (0mm, 150mm, and 300mm), and eccentricity (0mm, 20mm, 40mm, 60mm, and 80mm). In addition, the calculation formula for estimating the ultimate bearing capacity of the LFTST columns was derived employing the double coefficient product method. The proposed formula was validated by experimental and FE results.