Analytical and numerical studies on flexural resistance of fold-fastened multi-cellular steel panels

Fold-fastened multi-cellular steel panel (FMSP) is a novel type of cold-formed steel (CFS) built-up member, which is manufactured by connecting multiple FMSP cells. When connecting these cells, folded regions can be formed by lapping the FMSPs cells end to end, and indentations are used as fasteners during the manufacturing process. In this study, the flexural resistance of FMSPs was numerically and analytically investigated. Firstly, the refined finite element (FE) models were developed to simulate the flexural behavior of FMSPs. The accuracy of FE modeling method was validated by comparing the numerical results with experimental results obtained from the published literature about these investigations for CFS built-up members in terms of their moment capacities, moment-deflection curves and failure modes. Then, substantial parametric analyses involving a total of 105 different FE models of FMSPs were carried out to study the effects of steel thickness and strength, cellular dimension, width of fold-fastened regions and indented spacing on the flexural behavior of FMSPs. Finally, a sectional analysis based on the effective width method (EWM) was adopted to predict the ultimate flexural resistance of FMSPs. The results revealed that steel thickness and web plate depth have a great effect on the flexural behavior of FMSPs, while there was little influence on the ultimate load in other parameters. Moreover, the decrease in both width-to-thickness ratio and aspect ratio will lead to better ductile behavior for FMSPs. In addition, the EWM adopted in this study can agree well with the FE results, achieving better predicting results compared with other methods; therefore, this method is valid and well fits the practical needs.