Compressive Bearing Capacity Of Corroded Single-Angle Connected With One Leg

Transmission tower is an important part of transmission line project, and it is very important to the safe operation of power line. However, due to the long time open-air operation, polluted air, acid rain, acid soil, coastal environment and other adverse factors, result in the corrosion of transmission towers, leading to angle steel section weakening or even perforation or other outstanding problems, which has a serious impact on the security of the transmission towers. Therefore, to study on the carrying capacity of corroded steel angle has important significance.The corrosion condition of transmission line towers in Xuzhou was investigated. The investigation results show that some transmission towers has obvious corrosion phenomenon. The corrosion mainly occurs in the main bearing members, horizontal bars, grounding devices, tower foot bolts and other components bearing great force, close to the groud, or easily water agglomerated.Electrochemical accelerated corrosion device applicable to angle steel specimens was created, and the uniformly corroded angle members with etch pits which simiar to the angle members subjected to the actual condition were obtained through the corrosion device. Experimental research on eccentrically loaded uniformly corroded single-angle members connected with one leg was conducted. The relationship equation between the percentage of ultimate bearing capacity and the corrosion ratio of the corroded members was abtained. Test analysis results show that the ultimate bearing capacity percentage of the corroded angle members with different slenderness ratio and different cross-section types decreases linearly with the increase of corrosion rate, and the reduction rate tends to be uniform. The reduction rate of ultimate bearing capacity percentage of the corroded steel members is higher than the increase rate of the corrosion ratio.The method of calcuating the ultimate bearing capacity of the corroded angle members with the conversion thickness according to the relevant standards at home and abroad is proposed. It is recommended to use the <Technical code for the design of tower and pole structures of overhead transmission line> DT/L-2012 code to calcuate the ultimate bearing capacity of the corroded single-angle members connected with one leg.Angle-steel members with local corrosion were producted by using the method of artificial grinding. Experimental research on eccentrically loaded locally corroded single-angle members connected with one leg was conducted, and the effect of corrosion position, corrosion area on ultimate bearing capacity of the corroded single-angle members with different slendness ratio was experimentally studied. The finite element models of single-angle members were established using ANSYS software, and the reliability of finite element simulation is verified. The effect of section loss ratio, corrosion position and corrosion area on ultimate bearing capacity of the corroded single-angle members with different slendness ratio was studied. Test and finite element analysis results show that the ultimate bearing capacity of the component is gradually decreased with the increase of the loss rate of the local corrosion cross section. The influence of the local corrosion occurs on the connected leg on the failure mode and the ultimate bearing capacity of the corroded angel steel members is significantly higher than that occurs on the unconnected leg. The ultimate bearing capacity of the member is gradually reduced as the corrosion position on the connected leg is close to the middle span from the end. With the corrosion position on the unconnected leg close to the middle span from the end, the ultimate bearing capacity of the member increases first and then decreases. The relationship between the ultimate bearing capacity and the corrosion area on the connected leg is complicated, and the ultimate bearing capacity of the member even increases with the increase of the corrosion area on the connected leg. The ultimate bearing capacity of the member decreases with the increase of the corrosion area on the unconnected leg.A calculation method for the ultimate bearing capacity of the eccentrically loaded locally corroded single-angle members connected with one leg is proposed, based on the section loss ratio.