Experimental and Numerical Comparison of Flexural Capacity of Light Gage Cold Formed Steel Roof Deck

This paper presents an analysis of experimental data and compares it to two numerical analysis methods of light gage cold formed steel roof deck. The flexural capacity was determined upon the first failure mode of the light gage cold formed steel roof deck. A comparison of the experimental data was made to both the effective width method and the direct strength method. The objective of the comparison was to have a physical test provide the actual behavior of the light gage cold formed steel roof deck and grade how well the numerical analysis, effective width and direct strength methods, compare against the results. Material testing samples were taken from the steel roof deck and evaluated for the actual yield stress. This allowed for the most accurate comparison between the experimental results with the numerical analysis since the exact yield strength was used in calculation. It was found that the effective width method and the direct strength method vary in their prediction of the nominal moment capacity across material grades and deck thickness but tend to converge to a constant ratio, MnDSM /Mn EWM, at thicker deck gages. The effective width method was found to be more accurate for thinner gage steel roof deck, while the direct strength method was found to be more accurate for thicker gage steel roof deck. The effective width method is better at predicting the strength of steel roof deck, particularly the thinner gage ones, while the direct strength method provided a much quicker process to find the flexural capacity of the deck. Both methods can be used to determine the capacity of the deck and it is up to the end user to determine which method is appropriate for the given application