Buckling formulas for designing a column with Gigantochloa apus

Buckling resistance study is necessary because buckling is often a critical factor in column design. This study aims to predict the experimental formulas to fit the Gigantochloa apus bamboo’s buckling reduction factor (ψ) equations. In total, 235 G. apus bamboo samples (102 short, 69 intermediate, and 64 long culms) were tested by axial compression. A long column’s load-bearing capacity is less than a short column’s because of the buckling phenomenon. The buckling reduction factor (ψ) experimental data were curve-fitted by regression analyses, using a simplified Rankine–Gordon, Newlin-Gahagan, and Euler-Johnson formula. A continuous simplified Ylinen’s formula was also studied and produced the best-fit result since it has the highest coefficient of determination and the smallest standard error; thus, the Ylinen is the most recommended one in bamboo column analysis. The length should be limited so that the L/D must be less than 68, following Ylinen’s formula for ψ = 0.057. The ψ is reliable to reduce the G. apus’ compressive strength and load-bearing capacity characteristic value (Rk), of both non-graded or graded culms, which consider the failure of a column due to buckling.