AbstractExisting web crippling design provisions available in European, American, and Australian/New Zealand standards are based on empiric equations that differ from the approach adopted for the treatment of other instabilities such as local or overall buckling that employs χ-λ curves. Assessment of those empiric web crippling provisions based on test data available in the literature and reported herein for interior-one-flange (IOF) and interior-two-flange (ITF) loading conditions has demonstrated that they provide unsafe and inconsistent predictions, thereby highlighting the need to develop an alternative approach. Focusing on aluminum tubular sections subjected to IOF and ITF loading conditions, this article reports experimental and numerical results that were used to develop χ-λ curves for web crippling design. The tubular sections were made of 6060 and 6063-T6 aluminum alloys and were manufactured by extrusion. A total number of 12 tests were carried out and subsequently used to develop and calibrate a numerical model. The measured dimensions, material properties, and web crippling loads attained are reported. After successful calibration of the numerical model, parametric studies covering a wide range of slenderness and support lengths were carried out. In order to derive the χ-λ approach, three numerical analyses were performed as part of the parametric study: (1) a linear elastic analysis, (2) a plastic analysis, and (3) a geometrical and material nonlinear analysis. A total number of 288 numerical results were used to derive the new method. Compared with European, American, and Australian/New Zealand standards, the derived χ-λ design method provides more accurate and reliable predictions for the web crippling of aluminum tubular sections.