Web crippling of cold-formed steel with offset holes under ITF loading: Experimental, numerical study and new design equation

This study investigates the web crippling behavior of cold-formed steel members with offset holes experimentally and numerically, proposing a new design equation. The experimental study includes a total of seven tests under the ITF loading condition, examining the parameters of hole size and distance from the holes to the loading plate. It was determined that hole size and the hole's distance from the loading plate play a significant role in determining web crippling capacity. To validate the experimental data and examine the effects of variables such as hole diameter to web depth, hole diameter to thickness, and distance from the holes to the loading plate to web depth on web crippling capacity, a total of 157 finite element models were developed. The results indicate that an increase in the hole size to web depth ratio and an increase in hole diameter leads to a reduction in web crippling capacity. When the hole is close to the loading point, an increase in hole diameter significantly affects the load-bearing capacity, whereas, at relatively greater distances, its effect is less pronounced. Based on experimental and numerical studies, a new design equation has been proposed, and its accuracy was evaluated through a reliability analysis, which revealed a mean deviation of just 0.2 %. The results indicate that the proposed equation provides consistent and reliable predictions for the web crippling capacity of members with holes. This work fills critical gaps in current design standards, which lack comprehensive guidelines for perforated CFS members under ITF loading.