The object of the research is aluminum brackets with two anchor fastenings and various overhangs of the cantilever part in the range from 120 mm to 270 mm. The purpose of this work is to develop a methodology for the numerical calculation of fastening elements of curtain wall systems considering geometric and structural nonlinearity. Three types of forces acting on the brackets are considered: tensile, bending and compressive. Method. A methodology for numerical modeling of the L-shaped bracket structure using plate finite elements in nonlinear calculations is proposed. The modeling results are tested because of a laboratory study. Results. Analysis of the bearing capacity results obtained using numerical models with plate finite elements and during the laboratory study showed sufficient consistency. The use of simplified methods for modeling fastening elements of curtain wall systems leads to an underestimation of the bearing capacity under tension by 37%, and to a significant overestimation under a bending load by 88%. © The Author(s), 2025