Post-tensioning
Sa Carneiro airport, Porto (Portugal)
Tensacciai started to operate in the field of post-tensioning in 1956 and in the sixties the beginning of the highway program in Italy offered many chances in the works of art, favoring in this way a remarkable development of the Company. The systems used by Tensacciai were those of partial tensioning. These systems were soon considered insufficient to the owner to face competition of simultaneous tensioning systems. A program of technological renewal began. 0,6” diameter strands started to be used, and the system of multiple and simultaneous tensioning was developed. The use of strand, at that time scarcely present in post-tensioning, made it possible to carry out a system of multiple tensioning which, by assuring the isotensioning to cable components under stressing, complied with a design requirement, not yet achieved by the other systems with the same efficaciousness. An important development was achieved in the seventies: the years of the completion of the big highway program in Italy and of the final success of Tensacciai, as the system universally became used in big public works and in the most important bridges. During the nineties Tensacciai has completely streamlined and innovated its technological and operating structure and has fully developed the electrically insulated post-tensioning system. Moreover, during year 2008 Tensacciai has finally obtained the European Technical Approval and subsequent CE marking for its post-tensioning system after 3 years of intensive testing campaign in several European laboratories. Post-tensioning tendons have been installed in several jobsites in all five continents, in wider applications in viaduct, bridges, tanks, buildings and foundations.
Tensacciai post-tensioning system
Multi-strands tendons foresee a wide range of anchorages and systems for different applications. Post-tensioning system is provided with European Technical Approval and CE marking. MTAI the MTAI monogroup anchorage range is now improved and completed. In fact, the MTAI system, with its compact geometry and reduced angle of deviation, is the most modern, high-performance Tensacciai development comprising also a dead anchorage type MTAIM. MTG coupling anchorage has been developed and improved, covering the full range of post-tensioning tendons. MTAIE external post-tensioning anchorage MTAID electrically insulated anchorage, widely used and tested in the world’s biggest full scale application, the 4,3 km long Piacenza viaduct. The production also includes the ST series anchorages, i.e. dead end anchorages with bond end anchorages, CU single strand coupling type, and the DF anchorage used for ring post-tensioning or for intermediate tensioning. Systems are also foreseen for the slab post-tensioning: the 1C15 monostrand unbounded system and the multi-strand bonded PTS system.
As a specialized contractor with decades of experience in the specific field, Tensacciai is able to provide not only the products and the installation but also, through their Engineering Department, all the activities involved in design, such as shop drawings, assistance to design, installation procedures, tension checking and other engineering services related to the installation of post-tensioning works. Tensacciai take care of all the placing, stressing, tension and deformation checking operations with their own specialized teams, taking full responsibility and applying Quality Assurance according to ISO9001.
Steel strand This document provides technical information regarding post-tensionig tendons made of strands 15,7 (0,6”S) or 15,2 mm (0,6”) diameter.
Tendons can also be made of 12,7 mm (0,5”) diameter strands: this system is less used but still available in Tensacciai product range.
Dimension and properties of 7-wire strands according to prEN 10138-3 (1) Steel name
Y1860S7
Y1860S7
Tensile strength Rm (fpk) [MPa]
1.860
1.860
Diameter D [mm]
15,7
15,2
Cross sectional area Sn (Ap) [mm2]
150
139
Mass M [g/m]
1.172
1.086
Permitted deviation on nominal mass [%]
±2
Characteristic value of maximum force Fm (Fpk) [kN]
279
259
Maximum value of maximum force Fm – max [kN]
329
306
Characteristic value of 0,1% proof force Fp0.1 (Fp0,1k) [kN]
246
228
Minimum elongation at maximum force Agt (L0 ≥ ) [%]
3,5
Relaxation after 1000 hours
at 0,7 Fm (2) [%]
2,5
at 0,8 Fm (3) [%]
4,5
Modulus of elasticity E [MPa] (notations according to prEN10138-3, in rounded brackets to ETAG013 where possible) Other typologies of strands are available on request, according to main international standards.
195.000
(1) Until prEN10138-3 remains a draft norm, standards and regulations valid at the place of installation can be used. (2) The requirement for 70% Fm is mandatory. (3) Values for 80% Fm may be agreed between supplier and purchaser.
Ducts
Ducts are made of bright or galvanized steel or plastic. The ducts have a corrugated surface to guarantee the adherence between the cable and the surrounding concrete.
Duct thickness vary from 0,3 up to 0,6 mm on request. These dimensions are indicative only: in any case they must comply with national standards and be in accordance with operating conditions.
Suggested technical data Strand no.
4
7
9
12
15
19
22
27
31
37
Internal Ø [mm] Grout requirement
45
62
72
80
85
95
100
110
115
130
[l/m]
1,2
2,3
2,8
3,6
3,8
4,7
5,2
6,2
6,9
8,6
Cement [kg/m]
1,9
3,6
4,5
5,8
6,1
7,5
8,4
9,9
10,8
13,8
High speed train line Roma Napoli, Colleferro (Italy)
Main features of cables using 15,7 mm strand Strand diameter nominal cross section area 150 mm2 nominal mass 1.172 g/m Number of strands
4
7
9
12
15
19
22
27
31
37
Nominal cross section area of steel Ap [mm2]
600
1.050 1.350 1.800 2.250 2.850 3.300 4.050 4.650 5.550
Nominal mass of steel [kg/m]
4,69
8,20
10,55 14,06 17,58 22,27 25,78 31,64 36,33 43,36
Characteristic tensile strength fpk = 1.860 MPa Characteristic ultimate resisting force of tendon Fpk [kN]
1.116 1.953 2.511 3.348 4.185 5.301 6.138 7.533 8.649 10.323
Main features of cables using 15,2 mm strand Strand diameter nominal cross section area 140 mm2 nominal mass 1.093 g/m Number of strands
4
7
9
12
15
19
22
27
31
37
Nominal cross section area of steel Ap [mm2]
556
973
1.251 1.668 2.085 2.641 3.058 3.753 4.309 5.143
Nominal mass of steel [kg/m]
4,24
7,60
9,77
13,03 16,29 20,63 23,89 29,32 33,66 40,18
Characteristic tensile strength fpk = 1.860 MPa Characteristic ultimate resisting force of tendon Fpk [kN]
1.036 1.813 2.331 3.108 3.885 4.921 5.698 6.993 8.029 9.583
The maximum prestressing force to be applied on the tendon is specified in the national standards and regulations in force in the place of use.
Tensacciai post-tensioning system MTAI system, with its compact geometry and reduced deviation angle, is a guarantee for high performance, both for internal and external post-tensioning systems.
Metallic or PE duct
Hdpe connector
Cast iron block MT anchor plate
Removable grouting cap
MTG system is the range of anchorages suitable for the coupling of cables. It is fully integrated with the MTAI system and allows installation of cables in different separate stages.
Wedges Spring
duct
MTG anchor plate
Steel connector
Post-tensioning system range Post-tensioning tendons anchorages are classified in live anchorages, dead anchorages, couplers, annulars, external and electrically insulated.
Internal MTAI type
Internal MTAIM type
Electrically insulated MTAID type
Coupler MTG type
External MTAIE type
Annular DF type
Post-tensioning system Center and edge distance
MTAI system size
4
7
9
12
15
19
22
27
31
37
Minimum edge distance (A) [mm] not including cover
fcm,0 - cyl = 25 MPa
125
165
190
220
250
280
305
340
365
410
fcm,0 - cyl = 33 MPa
110
145
165
195
220
245
265
300
325
360
fcm,0 - cyl = 45 MPa
95
130
144
170
190
215
230
260
280
310
Minimum center distance (B) [mm]
fcm,0 - cyl = 25 MPa
270
355
400
465
520
580
630
700
755
840
fcm,0 - cyl = 33 MPa
240
315
355
410
460
515
555
620
670
740
fcm,0 - cyl = 45 MPa
210
280
315
360
405
450
485
540
585
640
C’ - concrete cover in accordance with European Standard EN 1992-1-1 and national regulations valid at the place of use
Bursting reinforcement
MTAI system size Concrete strength
4
7
9
12
15
25
33
45
25
33
45
25
33
45
25
33
45
25
33
45
200
170
150
250
210
180
290
260
230
340
310
280
380
350
315
fcm,0 – cyl [MPa] Φs [mm] Φb [mm] SL [mm]
10 250
p [mm] No. of turns
200
360
50 5
MTAI system size Concrete strength
225
4,5
4
6
19
12 300
270
420
60 5
4,5
7
22
12 360
330
480
60 6
5,5
8
27
14 420
360
510
60 7
6
8.5
31
14 450
420
60 7,5
7
37
25
33
45
25
33
45
25
33
45
25
33
45
25
33
45
410
380
360
470
430
400
500
470
440
540
500
470
560
530
500
fcm,0 – cyl [MPa] Φs [mm] Φb [mm] SL [mm]
16 570
p [mm] No. of turns
510
450
660
60 9,5
8,5
7,5
11
16 540
480
720
60 9
8
12
20 600
540
750
60 10
9
12,5
20 630
570
780
60 10,5
9,5
13
20 720
630
60 12
10,5
MTAI system
MTAIM system
MTAI system size
4
7
9
12
15
19
22
27
31
LTOT [mm]
475
531
688
708
736
783
823
848
1.009 1.107
S [mm]
150
180
200
220
250
280
300
325
350
400
h [mm]
45
49
52
62
69
74
80
87
91
96
hm [mm]
77
84
84
92
98
106
110
115
122
131
d (int/ext) [mm]
45/50
62/67
72/77
80/85
85/90
95/100 100/105 110/115 115/120 130/135
37
MTG coupler system
MTG system size
4
7
9
12
15
19
22
27
31
37
A [mm]
185
215
230
248
265
280
340
340
390
430
B [mm]
90
100
105
104
110
120
120
120
140
150
C [mm]
330
380
400
430
460
460
600
600
730
815
D [mm]
100
120
180
190
208
225
240
250
300
360
E x E [mm]
150
180
200
220
250
280
300
325
370
400
F [mm]
45/50
62/67
72/77
80/85
85/90
95/100
100/105
110/115
115/120
130/135
MTAID system Electrically insulated post-tensioning
MTAID anchorages for electrically insulated post-tensioning meet the demand for total protection of pre-stressing cables from corrosive agents. This protection is total and permanent, since the cable is enveloped completely in a protective sheath from outside agents, starting from the anchoring blocks. Protection by envelopment consists of dielectric material made of high-density polyethylene that covers the strands also in the anchoring areas. In this post-tensioning application, the anchoring discs of the strands are separated from the cast-iron blocks of the ends by means of rings made of dielectric material capable of withstanding the prestressing effort without becoming deformed. The polyethylene connectors that are positioned inside the cast-iron blocks lead out from the separating rings; then they are connected to the sheaths by means of elements that make the system completely waterproof.
Electrically insulated post-tensioning system offer measurable advantages:
High speed train line Milano Napoli, Piacenza viaduct, Piacenza (Italy)
• electrical insulation of the cable from the surrounding environment; protection against corrosion caused by electrochemical phenomena; • impermeability of the duct; protection against corrosion caused by oxidation and chlorides attack; • total filling of pipes with mortar injection; • possibility of control during structure lifetime of the integrity of protection with electrical resistance measures; • use of special sheaths HDPE; reduction of friction losses.
MTAID system size
4
7
9
12
15
19
22
27
31
37
A [mm]
150
180
200
220
250
280
300
325
370
400
B [mm]
100
120
180
190
206
225
240
250
300
360
C [mm]
110
140
160
180
200
220
250
270
290
310
D [mm]
45
47
48
51
53
65
74
78
88
94
E [mm]
90
90
90
90
95
100
110
115
125
135
F [mm]
280
324
348
378
428
418
478
478
538
568
G [mm]
58/73
58/73
76/91
76/91
100/116
100/116
100/116
115/131
130/146
130/146
MTAIE system External post-tensioning
Is Tensacciai external-post-tensioning evolution, suitably designed for external cables where full replaceability and protection is required. System can be demounted and substituted
through the presence of an inner steel cone that separates strands and inner protective injection from the surrounding elements in the anchorage zone.
MTAIE system size
4
7
9
12
15
19
22
27
31
37
A [mm]
150
180
200
220
250
280
300
325
350
400
B [mm]
100
120
180
190
208
225
240
250
300
360
C [mm]
135
160
177
195
210
245
265
295
330
330
D [mm]
63/3,6
75/4,5
90/5,4
110/6,6
110/6,6
125/7,4
125/7,4
140/8,3
160/9,5
160/9,5
E [mm]
310
360
430
450
520
600
660
700
750
800
F [mm]
82,5
101,6
127
139,7
152,4
168,3
193,7
203
229
229
MTRN system Adjustable post-tensioning
Protection cap
Bearing plate
Protection tube
Compound sealing Injection pipe Galvanized greased and coated strand Nut Anchorplate MTRN Type Anti-corrosive compound The great advantage of this system is to allow force adjustment anytime, depending on the structure behaviour and construction needs. It also gives the possibility to monitor loads, especially in the period following the installation of cables, when either the strands relaxation or the viscous effects of concrete can affect the evaluation of forces. To allow the load check and adjustment, Tensacciai can provide MTRN anchorages, composed of a threaded anchorage with a nut, all protected with a cap filled with grease. The load adjustment operation is carried out with a special annular jack, especially designed for these applications. This system is fully replaceable. Due to the progressive deterioration of already built structures, now the technique of external post-tensioning is becoming more common
during last years, especially in the cases where it’s necessary to increase considerably the resistance of load-bearing beams. On request Tensacciai can supply complete monitoring systems, with load cells and data recording with alert system.
Salerno - Reggio Calabria Highway, rehabilitation of Incoronata viaduct, Polla (Italy)
CU coupling system
CU system size
4T15
(7T13)
A [mm]
7T15
9T15
12T15
15T15
19T15
22T15
27T15
(9T13)
(12T13)
(15T13)
(19T13)
(22T13)
(27T13)
675
800
950
1250
1.250
1.300
1.385
1.700
B [mm]
45/50
62/67
72/77
80/85
85/90
95/100
100/105
110/115
C [mm]
140
159
177
193
193
193
219
244
D [mm]
300
340
400
400
400
400
400
400
E [mm]
-
-
800
800
800
800
800
600
F (mm)
-
-
-
1.200
1.200
1.200
1.800
1.400
ST dead end system
ST system size
4
7
9
12
15
19
A [mm]
-
80
-
80
-
-
B [mm]
210
240
-
400
-
-
C [mm]
80
-
160
160
160
240
D [mm]
80
-
160
160
160
240
E [mm]
10
10
12
14
14
14
F [mm]
50
50
60
60
60
70
G [mm]
250
350
400
400
400
400
H [mm]
800
800
800
800
800
900
I [mm]
100
100
150
150
150
220
DF system Annular post-tensioning
Special rectangular anchorages are used for ring post-tensioning: these anchorages also uses a special deviator for tensioning with mono-strand jacks.
DF system size
2
4
6
8
12
A [mm]
85
90
110
115
120
B [mm]
55
60
80
85
90
C [mm]
90
100
140
150
160
D [mm]
100
160
230
320
400
E [mm]
70
80
100
130
160
F [mm]
560
710
860
950
1200
G [mm]
170
200
240
300
330
H [mm]
140
170
210
270
300
Additional sizes available on request
Derivation tunnel for hydroelectric plant, Presenzano (Italy)
Malampaya off shore gravity structure, Olongapo (Philippines)
Post-tensioning system for buildings
Unbonded
Bonded
Monostrand system (1C15)
Multistrand system (PTS)
• Strands are covered with a special corrosion inhibitor grease and with a proof PE coating • No adherence between duct and concrete • High performance in service conditions (SLS) • Possibility to maximize cables eccentricity • Rapidity of execution and cracking phenomena reduction
• Strands are all inserted inside a duct, that is filled with cementious material after installation • High performance both in service (SLS) and ultimate conditions (ULS) • Multistrand system with 5 strands maximum
Strands used main characteristics
Steel designation
Y1820S7G
Y1860S7
Y1860S7
Diameter [mm]
15,2
15,2
15,7
Ultimate strength [MPa]
1.820
1.860
1.860
Area [mm2]
165
139
150
Maximum load [kN]
300
259
279
PTS system slab post-tensioning
PTS system size 3-13
3-15
4-13
4-15
5-13
5-15
(3 strands Ø 12,7 mm)
(3 strands Ø 15,2 mm)
(4 strands Ø 12,7 mm)
(4 strands Ø 15,2 mm)
(5 strands Ø 12,7 mm)
(5 strands Ø 15,2 mm)
A [mm]
170
170
220
220
220
265
B [mm]
75
75
75
75
75
75
C [mm]
50
60
50
60
50
60
D [mm]
125
155
160
205
200
250
E [mm]
190
190
220
220
220
270
F [mm]
45
45
45
45
45
45
G [mm]
45
45
45
45
45
45
H [mm]
72
72
72
72
72
92
I [mm]
20
20
20
20
20
22
1C15 system Slab post-tensioning
Live end
Dead end
Coupler
Center and edge distances valid for fcm,0 – cyl ≥20 MPa
c - concrete cover in accordance with European Standard EN 1992-1-1 and national regulations valid at the place of use
Plant for San Benedetto mineral water, Treviso (Italy)
A [mm]
B [mm]
C [mm]
D [mm]
180
140
80+c
60+c
Calculation notes
Friction losses The calculation of loss of prestressing force due to friction and wobble effects inside tendons is usually made starting from the following equation, taken from EN 1992-1-1:
ΔPμ (x) = Pmax (1-e-μ(Θ+kx))
where: ΔPμ (x) = loss of prestressing force from 0 up to x distance [kN] x = distance from the stressing point [m] Pmax = force at the stressing end [kN] μ = friction coefficient between strands and ducts [1/rad] θ = sum of the angular deviation from 0 up to x distance, irrespective of direction or sign [rad] k = not intentional angular deviation inside tendons, wobble coefficient [rad/m] Values for friction coefficient μ are between 0,18 and 0,22 while k values are between 0,005 and 0,01. Recommended values for calculation are μ = 0,19 [1/rad] and k = 0,005 [rad/m].
Basic elongation evaluation factors The elongation of the tendon, under the action of one or two jacks, is determined by the designer and verified at the construction site. The elongation calculation must clearly specify the theoretical elongation calculation and the corrective elements taken into account. It must be possible, with great accuracy, to establish the relationship between calculated elongation and measured elongation. In fact, secondary terms should be added to the elongation of the tendon along its length up to the anchorages, to obtain the real elongation. Real elongation measured at the construction site is thus defined as the sum of the following elements:
DLo = DLa + DLb + DLr + DLv
• DLa: theoretical elongation of the strand, calculated on the basis of the length between the anchorages, at one or two ends, depending on whether one or two jacks are used. • DLb: concrete elastic shortening. This bit of information, since it is extremely small, is usually neglected. • DLr: accumulation of deformations of the anchorage devices, for the deflection of the anchorages into the concrete and for the draw-in of the wedges. • DLv: draw-in of the strand wedges within the jack and jack deformations.
Equipments
Together with post-tensioning system Tensacciai has developed a range of dedicated installation equipments, including multi and mono stressing jacks, hydraulic pumps, grouting pumps and load cells. Nowadays Tensacciai is proudly involved in design and production of new stressing jacks, applying technologies and experience to obtain even more performing equipments.
Tensioning of vertical cables
PT series monostrand stressing jacks
Tensacciai manufactures 4 type of “PT” series jacks which differ in terms of tensioning section, weight and dimensions. All the jacks of the “PT” series are equipped with the automatic lock-off.
Type of jack
PT 150 KN
PT 200 KN
PT 250 KN
PT 300 KN
Capacity [kN]
150
200
250
300
Stroke [mm]
100
200
200
200
Weight [kg]
16
23
23
28
32,80
47,20
47,20
58,32
Max. tensioning pressure [bar]
550
450
550
550
Max. return pressure [bar]
180
180
180
180
Max. locking pressure [bar]
165
165
165
165
Connection [cm2]
2 tubes
2 tubes
2 tubes
2 tubes
A [mm]
85
100
97
110
B [mm]
600
1000
930
870
C [mm]
60
85
77
88
Tensioning section [cm2]
MT series multi strand stressing jacks
Tensacciai manufactures several types of “MT” stressing jacks (monogroup), ranging from 1000 up to 9000 kN. The “MT” jacks have been designed and built by Tensacciai considering stressing needs: minimum strand waste, jack built-in hydraulic circuit, controlled lock-off, easily removed and controlled wedges, jack rotation around its own axis, making easier to place and wedge onto the tendon. The extreme high functionality and material based quality have made of this jacks’ series its success even under the most severe operating conditions.
Type of jack Capacity [kN]
Stroke [mm]
Weight [kg]
Tensioning section [cm2]
Max. tensioning pressure [bar]
Max return pressure [bar]
Max. locking pressure [bar] Tensioning overlength
with lock-off [cm2] A [mm]
B [mm]
C [mm] D [mm]
E [mm]
MT1000KN MT1500KN MT2500KN
MT3000KN
MT3500KN
MT4500KN
MT6000KN
MT9000KN
1.000
1.500
2.500
3.000
3.500
4.500
6.000
9.000
250
250
250
250
250
250
250
250
100
180
290
350
420
600
1.000
1.250
155,51
302,18
361,00
400,55
492,44
725,71
879,60
1.400,50
sure [bar]
600
500
700
700
700
700
700
700
[bar]
180
180
180
180
180
180
180
180
re [bar]
165
165
165
165
165
165
165
165
35
37
37
38
38
45
51
52
cm2]
th
950
930
951
984
970
1.107
1.237
1.016
155
130
150
154
148
200
207
195
137
152
173
195
214
243
295
322
162
185
213
236
252
310
380
407
248
310
339
370
415
512
615
714
Detailed technical sheets and instruction manual are available on request.
MTX series multistrand stressing jack
The “MTX” series jacks, as natural evolution of the “MT” series jack, have been designed and built for stressing in very restricted areas, where the overall round dimensions of the jack are fundamental factor.
Type of jack
MTX2500KN
MTX3500KN
MTX4500KN
Capacity [kN]
2.500
3.500
4.500
Stroke [mm]
100
100
250
Weight [kg]
350
420
600
Tensioning section [cm2]
409,00
564,22
636,43
Max. tensioning pressure [bar]
660
660
660
Max return pressure [bar]
100-120
100-120
100-120
Max. locking pressure [bar]
100-120
100-120
100-120
Tensioning overlength with lock-off [cm2] 23
26
26
A [mm]
650
665
680
B [mm]
150
160
165
C [mm]
180
214
255
D [mm]
305
347
400
E [mm]
390
466
537
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MTP series multistrand stressing jack
MTP series jack is the last evolution of Tensacciai stressing equipment. This series has been designed during last year after a long experience of many years on jobsites all around the world, and guarantee top efficiency level during installation.
Type of jack
MTP850KN
MTP1600KN MTP2600KN MTP3500KN MTP5500KN MTP7000KN
Capacity [kN]
850
1.600
2.600
3.500
5.500
7.000
Stroke [mm]
150
250
250
250
250
290
Weight [kg]
95
195
258
665
570
1200
Tensioning section [cm2]
194,78
278,02
549,78
674,49
987,30
1.237,00
Max. tensioning pressure [bar]
465
570
485
495
497
560
Max return pressure [bar]
200
200
200
200
200
200
Max. locking pressure [bar]
100
100
100
100
100
100
Tensioning overlength with lock-off [cm2]
500
750
880
1.200
1.300
1.500
A [mm]
493
780
900
1.170
1.124
1.281
B [mm]
217
165
195
285
217
323
C [mm]
136
170
227
225
256
320
D [mm]
146
218
270
291
336
396
E [mm]
230
280
375
417
496
560
Pumps and equipment
Stressing pump Tensacciai offers a wide range of hydraulic pumps, which differ in terms of performance ratings, dimensions and weight. The “PT” series jacks require stressing pumps with power ratings ranging between 2.2 and 10 kW. The MT, MTX and MTP series jacks require stressing pumps with power ratings ranging between 7.5 and 30 kW. All Tensacciai pumps are equipped with an automatic lock-off circuit.
Grouting pump The “GP” pump is available in various models which differ in terms of performance ratings. The grouting pump consists of an eccentric screw pump, a mixer and a turbomixer. All the machines are equipped with a push-button control panel.
Vacuum pump
Strand pushing machine
Tensacciai offers vacuum pumps with power ratings ranging from 4 kW to 7.5 kW. This pump is used to inject grout under a vacuum, thus guaranteeing perfect grouting without any air entrance.
This equipment, designed to insert the prestressing strands into the sheaths, consists of a hydraulic pump and a unit that pushes the strand into the sheath. The two units can be installed at a remote location. Tensacciai also offers various models to meet all construction site requirements.
Extrusion jack
Bond end machine
The equipment consists of a highpowered portable jack (XG2), fed by a hydraulic pump. This jack extrudes passive anchorages (compression grips) at the ends of the strands. The jack drive will vary depending on the type of pump to which it is connected.
The equipment consists of an automatic pump XST/3” and an operating unit (jack UST/3”) that opens the strand. The bond end operation is completely automatic, controlled by an electronic device that regulates both time and force.
Post-tensioning bars
Products Tensacciai supplies bars with continuous thread for post-tensioning applications, such as buildings, roads and viaducts, tunnels and mines. These systems can be provided in diameters varying from 12 to 75 mm, and are used worldwide in post-tensioning and in pre-tensioning systems application. The advantages in the use of these post-tensioning systems are several and are supported by excellent results achieved in various jobsite. Usable for all reinforcing systems, different corrosion protection systems and steel grades are available.
• Ease of handling on-site. • Continues thread along the entire length of the bar, which ensures optimal adhesion with the cast in concrete. • Cut to size and possibility of extension using couplers in any position of the bar. • Different possibilities for protection against corrosive phenomena: galvanized, hot dip galvanized, epoxy coated, painted acc. DV-Norm. For special applications further steel grades are available.
Coupler Nut Threaded bar Bearing plate
Application field • Prestressed concrete structures • Rehabilitation of buildings • Temporary supports
Steel bars carachteristics
Continuous threaded bar left hand thread hot rolled, ribbed SAS 670
Y 1050
d
[mm]
18
22
25
28
30
35
43
57,5
63,5
75
max dA
[mm]
21
25
28
32
34
40
48
63
70
82
fy / ft / A10
670 N/mm² / 800 N/mm² / 10%
Ft
[kN]
195
300
390
490
565
770
1.170 2.080 2.540 3.535
A
[mm²]
250
375
491
616
707
962
1.466 2.597 3.167 4.418
Continuous thread bars right hand, hot rolled d
[mm]
18
26,5
32
36
40
47
57
65
75
max
[mm]
21
31
37
42
46
53
64
72
82
dA
fy/ / fpk / A10
950 N/mm² / 1050 N/mm² / 7 %
Fpk
[kN]
255
580
850
1.070 1.320 1.820 2.671 3.447 4.572
A
[mm²]
241
551
804
1.020 1.257 1.735 2.581 3.331 4.418
ft = minimum ultimate strength Ft = minimum ultimate load Agt = percentage total elongation at maximum force A = area A10 = ultimate elongation evaluated on 10 diameters
835N/mm²/1035 N/mm² / 7%
Accessories
Several kind of accessories are available to satisfy all design requirements. Full range set of couplers, nuts and anchor plates, including special pieces could be realized on request.
Tensacciai is able to provide a wide range of products customisation which enables use in new and different shapes.
Metallic end cap are always placed when it is necessary to provide a protective injection in the anchorage zone.
Anticorrosion protection N°
Coating
ID
thickness
Reference code
bar length
1
spray galvanization
GV
m = 8±2m
DIN 50961
on request
2
hot galvanization
FV
m = 100±20m
DIN EN ISO 1461
on request
3
epoxy coating
EP
m = 200±50m
ASTM A 934 / A 934M
15 mt
ASTM A 775 / A 775M
Tenso-inox
When it is necessary to ensure a long life service to the structure, even if it is exposed in a particularly aggressive environment, and also a high resistance to corrosion and fatigue with high mechanical strength and ductility is required, TENSO-INOX systems can be used: modern systems with a wide range of use. Developed to meet the demand for solutions with high mechanical characteristics.
That is why we provide the indications necessary to design for the most appropriate applications. Tenso-inox bars are made of special stainless steels by process of hot rolling, according to EN 10088 / 3 standards and certified according to EN 10204 3.1.B. Tenso-inox bars are manufactured through hot rolling process, in special high resistance and high yield strength steels, with resilience at -20 ° C> = 27 J.
Different typologies of accessories available
Tenso-Inox 1030 SS Nominal diameter [mm]
Area [mm2]
Breaking load Ft [kN]
20
320
329
22
387
398
24
461
475
26
541
557
28
627
646
32
819
843
36
1.035
1.066
38
1.156
1.190
40
1.280
1.318
50
1.985
2.044
Installation
Placing of the steel sheaths
Tensioning
The sheaths are fixed to the reinforcing steel of the structure to avoid that their position changes during the pouring of the concrete. For longitudinal post-tensioning they are usually placed following a parabolic lay-out.
Tensacciai jacks have been designed and built considering stressing needs: minimum strand waste (300mm to 500mm), automatic lock-off, easy removal and control of the wedges, jack rotation around its own axis.
Threading of the strands Strands are thread one by one inside the placed duct, using special strand pushing machine. Threading operation shall be carried out with care to avoid any damage to the strand or to the steel duct.
Grouting Grouting of tendon ducts shall be executed using a colloidal cement mortar, with a composition variable depending on temperature and length of tendons. Tendons ducts shall be provided with air vent pipes at the highest parts to ensure the air gets out and grout completely fills internal volume. Grouting equipment consist of an eccentric screw pump, a mixer and a turbo mixer.
Bridges
High speed train line Milano Napoli, Piacenza viaduct, Piacenza (Italy) Electrically insulated post-tensioning
High speed train line Milano Torino, Marchiazza viaduct, Vercelli (Italy) Electrically insulated post-tensioning
Bridges
Imigrantes Highway, San Paolo-Santos (Brasil)
Metro project, Dubai (UAE)
Bridges
Central corridor, Muscat (Oman) Tiziano bridge, Alessandria (Italy)
Funchal airport extension, Madeira (Portugal)
Bridges
Rabat – Fes Highway, section 2 (Morocco)
Adriatic LNG project Mooring Dolphins, Venezia (Italy)
Bridges
Loureiro viaduct, Calhandriz (Portugal)
Metro railway viaduct, Delhi (India)
Bridges
Covas viaduct, Galizia (Spain)
Head Office: via XX Settembre, 24 20123 Milano (Italy) tel. +39 024300161 fax +39 0248010726
[email protected] Office in Rome: via Lutezia, 2 00198 Roma (Italy) tel. +39 0632111820 fax +39 063219854
[email protected] Factory: via 25 Aprile, 8/10 20016 Pero, Milano (Italy) tel. +39 0238100064 fax +39 0233910227
[email protected] www.tensacciai.it
