Study on the wind-induced fatigue behavior of high strength bolt of lightning rod flange joint

• 1、College of Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, China

Abstract：In order to study the influence of wind load on the fatigue performance of high-strength bolts at the flange joints of framed lightning rod structure, this paper adopts a two-way fluid-structure coupling method to conduct three-dimensional numerical wind tunnel simulation of framed lightning rod structure and flange joints. Based on the combination of the rain-flow counting method, the equivalent stress amplitude formula and the constant amplitude fatigue test data of M24 high-strength bolts, the fatigue life of high strength bolts with flange joints is predicted under different wind speeds. The analysis results show that the stress concentration position of the high-strength bolt used for flange joints is obviously affected by the wind environment field, and the stress concentration position of the high-strength bolt at the windward stationary point is the largest. Moreover, the stress concentration position is basically consistent with the fracture position of the constant amplitude fatigue test. The transverse and downwind displacement responses of high-strength bolts are easily resonant with the first four frequencies of the structure, especially at frequencies of 0.40 Hz and 1.96 Hz. Different wind speed combinations have great influence on the fatigue life of high-strength bolts. The equivalent stress amplitude growth rate calculated under the combined wind speed difference of 10 m/s is 2.8 times larger than that under the combined wind speed difference of 5m/s, and the second-order effect on the structure is more obvious.

Keywords： bidirectional fluid-structure coupling high strength bolt three-dimensional numerical wind tunnel simulation flange joint the wind vibration fatigue