- 10 mm
between verticals and the lattice girder, of members at the outrigger, at splices, et cetera) are riveted.
The construction of the two five-tiered towers started in spring 1928. The first drum was constructed with help of an inner wooden scaffolding, which supported the structure at certain locations. By mid March, the
erection of the second drum started. Unlike in the case of the neighbouring three-tiered towers, which were built conventionally with an assembly platform on top ofeach hyperboloid, a new construction method was used for the subsequent upper drums. Here, the telescope method was employed, which had already proven efficient in the erection of the Sabolovka tower a few years earlier. (See fig. 5)
The subsequent sections were assembled inside the shaft. Their feet were pulled towards the center with a wooden corset. Five wooden derricks located at the upper lattice girder of the last drum then lifted the next section to the top. Once the section had reached its intended height, the mountings were slowly released. Then the feet were bent outwards to the ring and were connected at their final position.
The construction of one drum element needed about six to eight weeks. The towers were completed in 1930. The employed telescope method explains why Suchov designed the lower sections without a real "necking", even though it would have been structurally advantageous.
3 SUCHOV'S STRUCTURAL ANALYSIS
Suchov's original calculations for the tower resurfaced in the town archive of Nishni Novgorod in 2007. The 10 page typewritten structural analysis comprises load assumptions, steel member design as well as the design of the riveted connections and the foundations.
Referring to load combinations given by the Russian building code, Suchov states that the highest forces in the tower are caused if "the transmission lines aren't ruptured, no ice build-up exists, and the wind pressure is 250kg/m2".
The design wind pressure of 250 kg/m2 - constant over the height of the structure - is used to calculate the resulting forces on the different hyperboloid sections and at the base. This design pressure is applied on all the vertical members, using their unprojected length times the width of the steel angles as the reference area.
To account for wind shielding at the sides ofthe ring elements, Suchov uses the following formula with the diameter D and the width of the steel angle b to calculate the resulting horizontal wind force on one ring.
The resulting overturning moment of the tower is computed as 7384.21 tm; the self weight of the tower including the weight of the power lines is 144.26 t.
The forces on the verticals are calculated for each section with the z following equation:
with the overturning moment M, 2n the number of verticals, and the radius of the considered ring r.
Hence, the highest forces in the first section due to dead load and wind are:
This load is used to design the verticals in the first hyperboloid. As buckling length, the distance between the support and the connection between the verticals and the first horizontal ring is used. Suchov argues that the connections provide enough torsional restraint, so that column buckling of the L - shaped vertical will not occur around the principal but the strong axis. The allowable maximum compressive stress is computed with the following formula:
with slenderness ratio X = lc/i. In this manner, the verticals of the first section are designed. (E.g.L120x120x12withiy = 3.65 cm, A=27.54 cm2 t = \c = 244cm => X = 67
=> fc.« = 0,4 x (3100 - 11.4 x 67) = 934 kg/cm" => tc = 25300kg/ 27.54ctn = 920 kg/cm"< fcm3X)
This procedure is repeated with the respective overturning moments to design the L-shaped verticals of the higher hyperboloid sections.
Finally, the riveted connections of the first vertical of each section are designed. The combined shear and bearing pressure appears to be at the maximum 800 kg/cm2 for 7/8 inch rivets. 7/8, 3/4 and 5/8 inch rivets are used for the connections according to the calculations.
In addition, the calculations entail the design of anchor bolts, the steel members at the top, the stability against overturning of the structure as well as the design of the concrete foundation. There is no structural design of ring elements or lattice girders included in the original calculations. (Suchov 1927)
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