Numerical modeling of steel beams strengthened with CFRP sheets under fatigue loading

Analysis of structural components under fatigue loading due to the complexity of the loading is one of the most challenging problems in civil and structural engineering field. In order to find the fatigue life of a structural member, the costly and time-consuming experiments must be conducted while the collected data is very scattered and cannot be used for other conditions and problems. Therefore, finding effective numerical models to analyze a member subjected to fatigue load, could reducing time and expenses while could offer a systematic and general solution in variety of conditions. In this research, using the findings of a previous experimental study, the behavior of CFRP retrofitted and unretrofitted notched steel beams under fatigue loading has been studied by finite element by numerical modeling in a commercial finite element software. In this study, 11 notched CFRP retrofitted and unretrofitted steel beams (hot-rolled W5×10 made of A36 steel) were modeled and fatigue loaded until failure with stress range between 207 and 379 MPa under frequency of 5 to 10 Hz. The results of numerical modeling were compared with the results of previous experimental study and several equations were presented to estimate the fatigue life of unretrofitted and retrofitted specimens. The normalized stiffness losses of specimens were investigated as well. The verifications showed that numerical models and extracted equations have good agreement with the experimental results.