Research on Equivalent Wind Load Spectrum Acquisition and Remaining Fatigue Strength Method of Double Active Arm Type Holding Pole

Abstract

AbstractIn order to study the wind load fatigue residual strength in in-service holding poles for preventing disasters, and improving load-bearing capacity reliability. Firstly, using the Davenport wind speed spectrum to simulate the wind speed, it will be the input load of the finite element dynamics model of the 2 × 40 kN double active arm type holding pole (DAATHP). The stress time history curve at the welding section of the main chord at the bottom of the tower shaft is obtained at the working condition with the wind angle of 0°, 45°, 90°, and 135°. The rain flow counting method derives the statistical characteristics of the mean, amplitude, and frequency of stress at four wind angles. Secondly, the frequency of wind load under four wind angles is extended, and the synthesized fatigue load spectrum is used as the equivalent wind load spectrum. Finally, the Paris-Eadogan equation is used to derive the calculation formula of fatigue residual strength of the main chord at the bottom of the tower shaft, and the functional function of the main chord is established and then the failure probability formula is derived by combining the equivalent wind load spectrum. It is found that, compared with the ANSYS calculation results, the error of the predicted stress spectrum of the proposed method is minor, only 7.95%. It is verified that the proposed method can efficiently obtain the equivalent load spectrum of the DAATHP. The results indicate that it is feasible and practical to apply the proposed method to calculate the remaining fatigue life of the DAATHP.