Fatigue strength of coped steel beams

To investigate the fatigue behavior of coped beams, nine full-scale specimens are tested; stress range and cope radius were the two test parameters. It is found that the stress concentration effect produced by the cope geometry is very localized and, as expected, increases with decreasing cope radius. The fatigue life of the specimens decreases with either increasing nominal stress range or decreasing cope radius. The finite element method is employed to investigate the stress concentration produced by the cope geometry. This analysis has results that show good agreement with the test results. Linear elastic fracture mechanics is used to analyze the fatigue strength of the test specimens. Reasonable agreement is obtained between the analytical results and the test results. Based on the analytical study and the limited number of experimental data, it is recommended that the actual stress range, which is the nominal stress range multiplied by the stress concentration factor, could be used along with category C from the S-N curves in the AISC specification when one is designing coped beams subjected to fatigue loading.