L'analisi dei strallato pilone a traliccio in acciaio sottoposto a carichi ambientali

quattro torri di comunicazione ferro / tubo angolo zampe
gennaio 12, 2019
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gennaio 21, 2019

L'analisi dei strallato pilone a traliccio in acciaio sottoposto a carichi ambientali

L'analisi dei strallato pilone a traliccio in acciaio sottoposto a carichi ambientali

piloni di acciaio sono tra i più efficienti strutture portanti nel campo di costruzione grattacielo. L'analisi non lineare di un strallato pilone a traliccio acciaio viene condotta utilizzando SAP 2000 Programma elementi finiti per vari spessori di ghiaccio al 1500 m di quota. Dopo definizione del modello geometrico e trasversale- proprietà di sezione, varie combinazioni di carico vengono analizzati. Finally, la velocità del vento- rapporto spessore del ghiaccio si ottiene, e la velocità massima del vento che la struttura possa sopportare è determinata per vari spessori di ghiaccio.

  1. Introduction

Lattice mast is a general name for different kinds of steel masts.A lattice mast or truss mast is a freestanding framework mast. These structures can be used as transmission masts especially for

voltages of more than 100 kilovolt, as radio masts (self-radiating masts or carriers for aerials), or as observation masts for safety purposes. Big and heavy frame sections are not required in these

masts. This is why they are lighter than other mast types, and the modules can easily be connected to one another.

Steel lattice masts have been used for many years in the countries where the ice and wind loads are considerable. This is due to increasing demands of modern industry with regard to communication and energy. There are different styles of masts on which small wind generators are mounted: freestanding, guyed lattice, and tilt-up. Freestanding masts are relatively heavy duty, and they stay upright without the help of guy cables. Guyed lattice masts use guy cables to anchor the mast and keep it upright using a relatively small quantity of concrete. Cables stretch from three points near the top of the mast to the ground at some distance from the base of the mast. These constructions are quite light compared to freestanding masts, and therefore constitute the least expensive means for supporting a wind turbine. però, they require a larger area to accommodate the guy cables.

The technical efficiency and durability of steel lattice masts have increased in recent years. The behaviour of steel lattice masts has been investigated in literature. As the design procedure is significant in these masts, the structural analysis is related to the geometrical model and section properties. così, the module production and assembly steps, and economic costs, are directly related to the design of masts. Steel lattice masts on land are vulnerable structures. They are mostly affected by environmental loading. Wind loads are the most effective design criteria for these structures. però, the ice effect must also be taken into consideration, especially at high elevations. In cold regions, these two effects are combined. Perciò, the relationship between the wind and ice must be investigated by conducting proper finite-element analyses to avoid the collapse of such structures. In this paper, the non linear analysis of a guyed steel lattice mast 80 m in height is performed using the SAP 2000 program. While the model is constituted according to TS 648 load conditions are taken from TS 498. The altitude of the structure is taken to be 1500 m, and the snow region IV is adopted, which is the most conservative option. In this way, the analysis can also be used for other snow regions. The structure was first analysed without any ice effect. Afterwards, the ice thickness was gradually increased, and the relationship between the wind speed and ice thickness was determined.

  1. Materialand method

Proper sections and angles of the steel lattice mast are first determined. Afterwards, the three dimensional finite element model is given in Figure 1. Top view of the model is presented

in Figure 2. Face sections of the model, showing the distances with angles, are shown in Figure 3 and Figure 4.

figura 1. 3-D modello

 

figura 2. Superiore vista

 

 

figura 3. A e B face sezioni

 

 

figura 4. C face section

tavolo 1. Materiale properties

Materiale

Tipo

Trazione

forza

[MPa]

Rendimento

forza

[MPa]

ST52 (S355)

510

360

tavolo 2. section properties

Membro

Tipo

Sezione

Tipo

Dimensioni

[mm]

Colonna

membri

Tubo

48×7

Verticale

membri

Circolare

16

Diagonale

membri

Circolare

16

Guy members

Circolare

16

tavolo 3 velocità del vento e carichi secondo altezza

Altezza

[m]

Vento velocità

“v”

[Signorina]

Vento caricare

“q”

2

[kg/m ]

0-8

28

50

8-20

36

80

20-80

46

130

A module 3015 mm in length is made of steel members. Columns are placed at an angle of 900 to the ground. Vertical steel members connect columns to one another, and are placed vertically with respect to the columns. Diagonal members are placed by definite angles to the columns, and they also connect the columns to one another. A column with diagonal and vertical members that constitute the module, are shown in Figure 5.

 

figura 5. Modulo membri

Guy members and modules are named according to the total height from the ground level. The guy and section numbers, with related heights, are presented in Figure 6.

tavolo 4. Altezza e neve proprietà

Altitudine

[m]

La neve

regione

La neve caricare qS

2

[kg/m ]

1500

IV

176

tavolo 5. Ghiaccio properties

Peso di unità volume

[kN / mm³ ]

7

ci sono 26 moduli nel montante reticolo. La colonna, verticale,e elementi diagonali in ogni faccia del modulo sono shownin Figura 7. direzioni del vento positivi e negativi che interessano il
Modulo vengono anche presentati nella figura.

tavolo 6 proprietà di sezione

 

Membro

 

Sezione

Tipo

Sezione

dimensioni

[mm]

Sezione

circonferenza

[cm]

Sezione

la zona

2

[cm ]

Colonna

Tubo

48×7

15.08

9.02

Verticale

Circolare

16

5.03

2.01

Diagonale

Circolare

16

5.03

2.01

Tipo

Circolare

16

5.03

2.01

Colonna

Tubo

48×7

15.08

9.02

Verticale

Circolare

16

5.03

2.01

Diagonale

Circolare

16

5.03

2.01

Tipo

Circolare

16

5.03

2.01

Colonna

Tubo

48×7

15.08

9.02

Verticale

Circolare

16

5.03

2.01

Diagonale

Circolare

16

5.03

2.01

Tipo

Circolare

16

5.03

2.01

Colonna

Tubo

48×7

15.08

9.02

Verticale

Circolare

16

5.03

2.01

Diagonale

Circolare

16

5.03

2.01

Tipo

Circolare

16

5.03

2.01

 

 

Load combinations used in the analysis are given in Eqn (1) and Eqn (2) as follows. The combinations are constituted by Snow loads, ice loads according to ice thickness values,

and wind loads effecting different heights of the lattice mast with wind speeds are given in Table 7.

 

Membro

La neve

caricare

2

[kg/m ]

distribuito

la neve caricare

[kg/m]

Ghiaccio

spessore

[mm]

distribuito

ice caricare

[kg/m]

Vento

velocità

[km / h]

Vento caricare secondo per altezza

[kg/m]

0-8 m

8-20 m

20-80 m

Colonna

 

176

 

30

5.15

 

209

12.18

19.49

26.81

Verticale

membro

4.42

3.03

4.06

6.50

8.94

Diagonale

membro

4.42

3.03

4.06

6.50

8.94

Tipo

4.42

3.03

4.06

6.50

8.94

Colonna

 

176

 

20

2.99

 

217

12.63

20.21

27.79

Verticale

membro

4.42

1.58

4.21

6.74

9.26

Diagonale

membro

4.42

1.58

4.21

6.74

9.26

Tipo

4.42

1.58

4.21

6.74

9.26

Colonna

 

176

 

10

1.28

 

223

12.96

20.73

28.50

Verticale

membro

4.42

0.57

4.32

6.91

9.50

Diagonale

membro

4.42

0.57

4.32

6.91

9.50

Tipo

4.42

0.57

4.32

6.91

9.50

Colonna

 

176

 

0

 

226

13.14

21.03

28.92

Verticale

membro

4.42

4.38

7.01

9.64

Diagonale

membro

4.42

4.38

7.01

9.64

Tipo

4.42

4.38

7.01

9.64

Effetti Carico laterale membri. carico di neve distribuito viene calcolato considerando superficie superiore dei membri.

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