Experimental Investigation On Bearing Capacity Of Built-Up Section Eccentrically-Compressed Member In UHV Transmission Tower

With the rapid development of power industry in China, the single-angle steelmembers of the traditional transmission tower can’t meet the requirements of ultra-highvoltage(UHV), multi-loop, high-load and so on. Also the steel of domestic transmissiontower before has been limited to two kinds of strength grades, Q235and Q345. Now,combining another same size steel angle with the existed single-angel member, whichwould form double-angle composited-section member subjected to eccentriccompression, is a common way to reinforce and mend the existed single-angletransmission tower. There are some differences in bearing capacity and failure modebetween the full scale transmission tower test and the current design technique. Thedomestic and overseas codes, which contain some unreasonable rules, don’t providedetailed design information for the double-angle built-up section member. Given thelack of the research achievement, a further research on double-angle cruciform memberis carried by doing experiments and analyzing with ANSYS in this paper.By doing experiments with double-angle cruciform section members, whosespecification were L160×14, we analyzed the ultimate bearing capacity of maincomponents which constitute UHV transmission tower. The specimens, whoseslenderness ratios were30,40and50, were divided into single internode and doubleinternode. And there were two kinds of eccentricity for every slenderness ratio. The testindicated that the failure mode was overall bending buckling rather than torsionalbuckling. Apparent warping occurred on the small slenderness ratio specimens.Meanwhile, considering the influence of the parameters which including differentratios of slenderness, different offsetting, we used the finite element method(FEM) toanalyze the bearing capacity of double-angle built-up section members consisted ofcommon specifications angle steel. Compared FEM results with test results, we couldfind that the deformation and bearing capacity based on the finite element model wereconsistent with test results. Through parameter analysis based on the validity of FEMresults, we put forward modified coefficient of calculated length which we can use it tocalculate the eccentric compression members by using the method of axial compressionmembers. Also, theanalysis of the calculated results, showed that the modifiedcoefficient was affected by slenderness ratios and offsetting. Finally, we got themodifier formulas for the modified coefficient of calculated length. Furthermore, this paper, based on the numerical integral method, analyzed therelationship of M P Φ for the composited section by programming with Matlab.Meanwhile, combining the inverse calculation segment length method with therelationship of M P Φ, we analyzed not only the correlative relationship betweenP/Py and M/M P, but also the relationship of M θ, which can be referred to designand calculate.