Thin-walled steel tubes are widely used in conical cylinder steel towers of wind turbines, which are prone to local buckling when the diameter-thickness ratios are large, leading to a decrease in the bearing capacity of the towers. A new structural type of longitudinal stiffened steel tube for wind turbine steel towers was proposed, and six specimens were tested under compression-bending load to study the effect of stiffeners types and diameter-thickness ratios on the compression-bending behavior of steel tubes. The experimental results showed that

with the same amount of the steel, the stiffeners could effectively prevent the local buckling of the steel tubes, resulting in changing the failure mode of the structure and increasing the plastic development, and thus improving the strength and ductility of the steel tube. The enhancement effect of T-type stiffeners is more significant. The experimental results were also compared with the FE model to verify the accuracy of the FE results. The ultimate strength of specimens was evaluated preliminarily by using the existing specifications, showing good agreement with the test results of the unstiffened specimens, while the ultimate strength of the stiffened steel tubes was underestimated.