Experiments And Analysis On The Ultimate Bearing Capacity And Stability Of High-strength Equilateral-Angle Steel Member

As the demand for electric electricity is increasing and the power grid technology is upgraded constantly, the scale of transmission towers becomes larger in our country. The steel of domestic transmission towers has been limited to two kinds of strength grades, Q235 and Q345. for a long time, Compared with the steel in advanced countries, the species of the domestic steel is few, its strength value is low and the room for choice is small. When the tower load is heavier, composite section can only be used to make up for the lack of low-strength materials, which increases the workload of designs and machinings. However, the characteristics of high-strength steels are high strength and strong bearing capacity. So, utilizing high-strength steels in transmission towers is one of effective measures to relax the contradiction above, which not only produce the technical and economic efficiency but also promote the construction level of transmission lines in our country.The study object in this paper is high-strength equilateral-angle steel member of Q460. To ensure that high-strength equilateral angles Q460 are applied to transmission towers reasonablly and safely, the test studies on the high-strength equilateral-angle steel members are carried out in this paper, which include L125x10 axial compressed tests of 5 groups of different slenderness ratios and L140x12 eccentric compressed tests of 3 groups of different slenderness ratios. The test results indicate that the design for the test devices are reasonable and meet the actual requirements. Meanwhile, the factors that effect on the ultimate bearing capacity of the angle steel are analyzed. The test data are compared with the calculation results of"Technical Regulation of Design for Towers and Pole Structure of Overhead Transmission Line"(DL/T 5154-2002) and ASCE. The column curve ofλ? ? is also painted. According to the analysis of test results, some adjustment for the code formula are made, and the slenderness-ratio correction coefficient of Q460 high-strength equilateral-angle steel member in cases of axial and eccentric compression are put forward.Finally, the stability of high-strength equilateral-angle steel compressed bar of Q460 L125x10,L140x12 is analyzed with the finite element analysis software ANSYS. The failure mode and ultimate bearing capacity under axial compression and eccentric compression are studied. The results of ANSYS are also compared with the test results. By means of tests and numerical analysis, it can be found that in the case of axial compression, the flexural-torsional buckling failure is liable to happen when the slenderness ratios is small, and the flexural buckling failure usually occurred when the slenderness ratios is large. ANSYS calculation results agree well with the test results.