GFRP布无损加固输电铁塔角钢受力性能研究

Study on mechanical behavior of angle steel of transmission tower strengthened with GFRP sheet

针对现役输电铁塔在覆冰、风荷载、边坡变形等作用下可能存在承载力不足的问题,研究玻璃纤维增强复合材料(GFRP)布无损加固铁塔角钢的受力性能。首先,利用文献中的物理试验对加固钢材数值试验方法进行验证;其次,以铁塔角钢为研究对象,基于验证的数值试验方法建立72组有限元分析模型,探讨长细比、GFRP布粘贴层数、粘贴长度等因素对角钢极限承载力的影响;最后,推导并改进GFRP布角钢复合构件理论承载力计算方法。结果表明:不同长细比对构件极限承载力影响较大,当角钢长细比大于70时,加固后的承载力提升不明显;增加GFRP布粘贴层数,角钢承载力大幅提升,粘贴8层GFRP布的承载力提升率最高达41.03%;柱中GFRP布粘贴长度为75%与粘贴长度为100%的角钢极限承载力相比提升不大,仅为0.27%~2.10%;对推导的GFRP布角钢复合构件理论承载力计算方法引入修正系数后,数值试验与理论计算值相对误差缩小至-2.70%~1.77%,有效提升理论解计算精度。在对现役铁塔加固时,只需对角钢全长的75%粘贴6~8层GFRP布进行加固,且对于长细比λ≤70的角钢加固效果更好。

To address the issue of insufficient bearing capacity of existing transmission towers under the effects of ice coating,wind load,and slope deformation,this study investigated the mechanical properties of GFRP-reinforced angle steel for tower reinforcement.First,numerical test methods for reinforced steel were verified using physical experiments from literature.Then,72 finite element analysis models were established based on the validated numerical test methods,with angle steel as the research object,to explore the effects of slenderness ratio,number of GFRP layers,and bonding length on the ultimate bearing capacity of angle steel.Finally,the theoretical bearing capacity calculation method of GFRP-steel composite components was derived and improved.The results show that the slenderness ratio has a significant impact on the ultimate bearing capacity of the component.When the slenderness ratio of the angle steel is greater than 70,the increase in bearing capacity after reinforcement is not significant.Increasing the number of GFRP layers significantly increases the bearing capacity of angle steel,with the highest increase rate of 41.03%achieved with 8 layers of GFRP fabric.The increase in bearing capacity of angle steel with 75%bonding length of GFRP fabric in the column is not significant comparing to the anglesteel with 100%bonding lenth,only ranging from 0.27%to 2.10%.After introducing a correction coefficient to the theoretical bearing capacity calculation method of GFRP-steel composite components,the relative error between numerical experiments and theoretical calculation values is reduced to-2.70%to 1.77%,effectively improving the accuracy of the theoretical solution.Therefore,when reinforcing existing towers,it is only necessary to reinforce 6-8 layers of GFRP fabric on 75%of the full length of the angle steel,and the reinforcement effect is better for angle steel with a slenderness ratio less than or equal to 70.