螺栓连接对外力荷载下输电塔的影响

摘要

为保证送电线路的安全运行,在输电塔设计过程中需对沿线的气象情况进行等效外力荷载的转换并模拟验算.传统的结构有限元分析方法通常将角钢间的螺栓连接简化为刚接或铰接,忽略其滑移、偏心效应,在进行外力荷载下的输电铁塔的力学特性分析中存在较大误差.基于ANSYS软件,在考虑塔身斜撑杆螺栓滑移的初始滑移模型的基础上,进一步引入塔腿和塔头部位螺栓连接的影响,建立了改进滑移模型,数值结果同时与初始滑移模型和两种传统模型进行对比.首先通过全尺寸塔的动、静态试验结果验证了新模型的合理性,进而研究最大工作荷载工况下的模型响应.结果表明:改进滑移模型优化了弯曲模态频率的预测,并能够真实模拟输电塔的变形和轴力情况.螺栓连接的影响程度还与荷载组合工况相关,对于分析最危险的导线断线工况,考虑塔腿和塔头螺栓连接的影响十分有必要.%To ensure the safe operation of transmission lines,it is necessary to convert metecorological conditions to equvalent external forces in simulation calculations in the design process of transmission tower.The traditional structural finite element analysis methods usually simplify the bolt joints of steel angles as rigid or pinned connections,ignoring the effect of slip and eccentricity.Using ANSYS software,on the basis of an original slip model,an improved slip model was built by further considering bolt joints in tower legs and tower head.Simulation results were compared with the original slip model and two conventional models.The rationality of the model was verified by the dynamic and static measurements of the full scale tower test,enabling the investigation of responses of the maximal working load conditions.It could be found that,the improved slip model optimizes the forecast of the bending modal frequencies and accurately simulates the real deformation and axial force of the transmission tower.The effect of bolt joints is related to the load combination conditions.Consideration of the effect of bolt joints in tower legs and tower head is necessary to the analysis of the most dangerous condition: wire breakage.