Tower at present materials mainly hot rolling Angle profiles is given priority to, supplemented by a small amount of steel pipe, steel varieties with Q235 and Q345 is given priority to, tower adopts galvanized anti-corrosion, use fixed number of year for about 50 years. Compared with the developed countries, variety, less intensity value is low, small can choice.

When tower load is bigger, can only adopt the method of combination section to make up for the shortcomings of low strength of materials, this will inevitably lead to the tower bar quantity and specifications, the joint structure is complex, the installation work, already caused the increase in engineering investment and resources waste, also affected the competitiveness of the industry in the international market. Along with the higher voltage level of 750 kv, 1000 kv ac uhv, plus or minus 800 kv uhv dc transmission line construction, as well as the use of large section and split conductor, tower design load increasing, such as the tower with steel strength too low impact of behave more and more prominent.

In terms of transmission line tower material, there are many countries in the world have adopted much more than the high strength steel. Japan in 1992 and 1999 successively built four with double circuit towers 1 000 kV line of 425 km, advocate material adopting steel tube steel yield strength 392 MPa, Japan 1 000 kV uhv line iron tower advocate material in steel pipe with steel yield strength of 392 MPa, the current specification and the steel yield strength increased to 440 MPa, most of the European and American countries adopt steel yield strength of 450 MPa. At present, the high strength steel basic used in Europe and the United States, Japan and other countries on the chongqing electric power tower above of 500 kV voltage class, new line iron tower advocate material are all made of high strength steel. Russia's listed in the specification for design of steel structure of the steel intensity level has reached 578 mpa.

Specification for design of steel structure in our country the highest strength grade is 420 mpa (Q420 steel), the overhead transmission line tower structure design rules of the highest strength grade is only 390 mpa (Q390 steel). From national design specification selection scope and project practical application, high strength steel used in our country level were significantly lagged behind some developed countries abroad.

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