螺栓松动对输电塔振动特性及抗风性能的影响研究

Study on the Influence of Bolt Loosening on the Vibration Characteristics and Wind Resistance of Transmission Towers

输电塔节点螺栓松动如未能及时发现,在风荷载作用下易造成节点损伤、严重时造成倒塌事件。以11BB-ZYT角钢输电塔为研究对象,首先开展铁塔半刚性节点模型研究,通过对不同节点刚度的分析,在ANSYS有限元软件中验证非线性弹簧单元模拟螺栓节点半刚性进行建模的可行性;随后开展螺栓松动对输电塔自振频率及抗风性能影响的研究,通过ANSYS有限元软件、结合输电塔真型试验测试,分别对比不同工况下自振频率、受风荷载影响塔顶位移和杆材应力变化。研究表明,输电塔振动受变坡处主材搭接节点螺栓松动影响较为明显,弯曲和扭转振动频率降幅达6%;斜材等位置螺栓松动对结构振动和抗风能力弯曲振动影响不大;塔顶最大位移和主材最大应力受风攻角影响明显,其中90°风攻角下塔顶位移达到最大值,45°风攻角下主材应力达到最大值。因此在输电塔设计时应加强对主材搭接节点螺栓的防松动设计,日常巡检中也应重点检查主材搭接处螺栓的拧紧情况。

If the bolts of the transmission tower node are loose and not found in time,it is easy to cause node damage under the action of wind load,and in serious cases,it will cause the collapse event.The 11BB-ZYT angle steel transmission tower is taken as the research object,and the semi-rigid joint model of the tower is first studied,and the feasibility of modeling the semi-rigidity of the bolt joint simulated by the nonlinear spring element is verified in ANSYS finite element software through the analysis of the stiffness of different joints.Subsequently,the study of the natural vibration frequency and wind resistance of the transmission tower by bolt loosening was carried out,and the natural vibration frequency,the displacement of the tower top and the stress of the rod under different working conditions were compared by ANSYS finite element software and combined with the true test of the transmission tower.The results show that the vibration of the transmission tower is obviously affected by the loosening of the bolts of the joints of the main material at the variable slope,and the bending and torsional vibration frequencies are reduced by 6%.The loosening of bolts at the position of inclined materials has little impact on the structural vibration,wind resistance,and bending vibration;The maximum displacement of the top of the tower and the maximum stress of the main material are obviously affected by the angle of attack of the wind.The displacement of the top of the tower reaches its maximum value under an angle of attack of 90°,while the stress of the main material reaches its maximum value under an angle of attack of 45°.Therefore,in the transmission tower design,the anti-loosening design of the bolts of the main material joint should be strengthened,and the tightening of the bolts at the joints of the main material should also be checked in the daily inspection.