FOUNDATION OF A 157 M HIGH TRANSMISSION TOWER

Abstract

In a city of Hungary known to have a weak subsoil, a microwave transmission tower 157 m high, with a cylindrical reinforced concrete shaft was built. In its design, possibilities of both spread foundation and deep foundation arose. Beyond dead and live loads, also other effects (wind load, seismic effects, uniform and nonuniform settlement, daily and seasonal temperature variations) had to be reckoned with. In case of spread footing, that should be 25-30 m diameter because of the extreme height, uneven settlement and tilting, rather than soil failure, were the main problems. Effects likely to cause eccentricity like wind load and building inaccuracies had to be analyzed. In case of a deep foundation, which is technically much better, the point of the large-diameter bored piles was suggested to be taken in a clay beginning at 25 m below the ground level, which is in a much better condition than the overlying one. At last. the tower was built on spread foundation. During and after construction, stresses under the slab footing were recorded, horizontal and vertical displacements of the tower observed.