DE1808462U - CONCRETE MAST. - Google Patents

Description

DR.-ING. BY KREISLER DR.-1NG. SCHÖNWALD DR. SIEBENEICHER DR.-ING. TH. MEYER

COLOGNE1, DEICHMANNHAUS

D 17 55O / 57b Gm February 16, 1960 B / Se

Benoit DAEIS,

7, Hue Garaneiore, PARIS 6e, France.

Jean HEEEHG,

117, rue du Öherche-Midi, PARIS, France.

LES TOLES INOXYDABLES ET SPECIALES ÜGINE-GUEÜGITOIT, 16, rue de la Ville-1'Eveque, PARIS 8e, France.

Concrete mast.

In order to increase the load-bearing capacity in the longitudinal and transverse direction of pressure-loaded concrete masts, as is well known, the concrete in a wooden formwork, which later removed, on a helical reinforcement with vertical axis and with a diameter slightly smaller than that of the mast, cast in such a way that the reinforcement is completely embedded in the concrete after casting. Such a reinforcement makes the expansion and the expansion of the concrete and causes a kind of shrinkage of the mast.

It is known that the effectiveness of this usual shrinkage is greater, the smaller the slope of the Spirals of helical reinforcement is. According to the innovation, the classic iron reinforcement in Helical shape can be replaced by a complete jacket made of sheet metal. This is how you get one Type of continuous shrinkage.

—2—

When this jacket is outside the mast instead of inside it as the helical one Reinforcement, the concrete can be poured directly into the mantle without the need for wooden formwork is. In addition, the outer sheet metal jacket can serve as the outer wall of the mast, which means that additional finishing is required not applicable.

However, if a metal other than steel is used for the sheet metal forming the jacket, it has a permissible Thickness and at a reasonable price does not have sufficient load-bearing capacity. Steel must therefore be used will. But with ordinary carbon steel the corrosion, which inevitably occurs after a short time, would be the Cause destruction of the mast.

It might be considered to paint the steel pipes, but if age and lack of maintenance to add it, it would be dangerous to have such treatment to risk with ordinary steels.

According to the furnace, stainless steel is therefore used, which, due to its great resistance to corrosion, has the disadvantage of all other metals avoids.

The innovation concerns a concrete mast, its characteristic The characteristic is that the poured concrete is surrounded by a jacket made of stainless steel sheet. A such a jacket serves at the same time for shrinkage, as reinforcement, as formwork and as a final outer wall. A only component replaces the shrink rings, the longitudinal reinforcement, the formwork and the processing of the outer wall.

The thickness of the stainless steel sheet used Steel depends on the diameter of the mast, its height and the load to be carried. In this regard, will refer to the table below:

! D. 0.7
1
1.2
1.5
2
2.5
3 0 10 cm T ^ 15 cm T 0 20 cm T 0 25 cm T 0 50 cm T 111
154
150
176
222
240
256 H 25th
29 H 41
55
59
64 H 61
78
90
102
115
124 H 84
104
118
142
164
176
190 H 4.20
5.95 2.85
4.00
4.90
6.00 2.20
5.00
5.75
4.60
6.00
7.60 1.75
2.45
5.00
5.75
4.90
6.00
7.25 1.45
2.00
2.45
5.00
4.00
5.00
6.00

D = thickness of the sheet in mm
H = height of the mast in m
T = permissible maximum load in t

The permissible loads given in the table are maximum values that do not take buckling into account. A reduction coefficient is therefore appropriate for these values the buckling depending on the height of the mast must be taken into account.

It is also known that the devices for the Shrinkage of concrete pylons through a helical reinforcement valid regulations a safety coefficient allow the load-bearing capacity of the shrunk concrete calculated by the quotient

^k 1 =

permissible load-bearing capacity of the non-shrunk concrete is expressed and which is equal to 2.5. The permissible Load-bearing capacity Eb is equal to 0.28.n90. n90 is the load-bearing capacity of 90-day-old concrete. The calculated load capacity k ^ Eb is equal to 2.5 Eb. The coefficient k ^ is given by the Given equation:

k ₁ = I + throws (I ^ a ^) n'e

in which:

M / ~ coefficient of the shape of the transverse reinforcement, the / '5.60 for continuous helical reinforcement,

2.80 for square connections and 2.80 ^ for rectangular reinforcements, Zy f = volume of the transverse reinforcements (shrink rings)

per unit volume of concrete, ef = pitch of the spirals (distance from axis to Axis of the transverse reinforcement), a = smallest dimension of the cross-section,

b = largest dimension of the cross-section, n'e = usual yield strength of steel, n90 = load-bearing capacity 90 days old concrete.

Since ef = 0 for an uninterrupted jacket, this equation reads:

= I + (5,6. Uft . 10)

n'e varies between 32 and 40 kg / mm for not rusting steel,

n90 varies between 300 and 400 kg / cm. It follows that

The uninterrupted jacket according to the hiring therefore brings with it a considerable saving in metal compared to the shrinkage caused by spirals, even when limited to the maximum coefficient of 2.5, which is specified by the applicable regulations.

However, this coefficient will be set higher in the event of shrinkage due to a sheet metal jacket made of stainless steel can.

By calculation it was found that a filled with concrete Pipe with a diameter of 10 cm and a wall thickness of 1 mm has a load-bearing capacity that is the same as that of a square one A mast with a side length of 20 cm or a round mast with a diameter of 22 cm.

example 1

A concrete pole with a diameter of 20 cm was sheathed with a sheet made of stainless steel with a wall thickness of 0.7 mm (Fig. 1).

The calculated shrinkage of concrete, which has a load-bearing strength of 360 kg / cm after 90 days, was as follows:

Rc = 101. 1.79 = 181 kg / cm ²

The calculated shrinkage coefficient k = 1.79. The volume of metal per unit volume of concrete was 0.014 m.

With the usual shrinkage would have to achieve the compensate for a helical spiral I ″ soft steel of 14 mm diameter with a pitch of 5 cm and 5 round longitudinal rods R of 10 mm diameter are used i.e. the total metal volume per volume

The unit of concrete would be 0.06 no than when using a jacket (Fig. 2).

The unit of concrete would be 0.06 m or 4.27 times as much

Example 2

A concrete pole with a diameter of 30 cm was attached to a sheet metal Sheathed from stainless steel with a wall thickness of 1.5 mm.

The shrinkage coefficient k was 2.12, the maximum load 196 t and the metal volume per running meter of the mast is approximately 11 kg.

With normal shrinkage, a helical spiral P of 17 mm diameter with a pitch of 5 cm and 5 round longitudinal rods R made of soft steel of 14 mm diameter are used i.e. about 31.5 kg of metal per running meter of the mast or about 3 times as much as when using a jacket.

The sheathing of such masts can be done by means of a pipe made of a sheet metal strip made of stainless steel

consists, which with; a slight overlap spirally wound and "electrically welded during the manufacture of the pipe will.

Other pipes can also be used that are below wound at an acute angle in a spiral shape and welded without overlap, or from a rolled one Sheet metal that is welded along a generatrix of the cylinder. In the latter case it would have to be resilience of the weld determined by previous pressure tests will.

Finally, drawn tubes can also be used.

Claims (3)

P.A.109 190 * 17.2.60 Protection claims 1. Concrete pole, characterized in that the poured concrete from a shell made of stainless steel sheet is surrounded. 2. Concrete mast according to claim 1, characterized in that that the jacket serves at the same time for shrinkage, as reinforcement, as formwork and as the final outer wall. 3. Concrete mast according to claim 1, characterized in that that the thickness of the stainless steel sheet used depends on the diameter of the mast, on its Height and the load to be carried.