Cantilever Tendon Prestressing Protocol for Giborim Highway Bridge

CONTENTS

1.0 GENERAL........................................................................................................................................ 1/69

2.0 ACTIONS OF PRESTRESSING.................................................................................... 2/69

3.0 GROUTING OF POST-TENSIONING TENDONS .......................................................... 4/69

4.0 SAFETY AT WORKS ................................................................................................ 6/69

5.0 CANTILEVER BOUNDED POST-TENSIONING TENDONS ................................... 6/69

5.1 ELONGATIONS AND PRESTRESSING – CANTILEVER '2E/2W' ......................... 6/69
5.1.1 PRESTRESSIN TENDONS OF HAMMER-HEAD SEGMENT.............................................. 7/69
5.1.2 PRESTRESSING TENDONS OF FIRST SEGMENT .......................................................... 11/69
5.1.3 PRESTRESSING TENDONS OF SECOND SEGMENT..................................................... 15/69
5.1.4 PRESTRESSING TENDONS OF THIRD SEGMENT ......................................................... 19/69
5.1.5 PRESTRESSING TENDONS OF FOURTH SEGMENT ..................................................... 23/69
5.1.6 PRESTRESSING TENDONS OF FIFTH SEGMENT .......................................................... 26/69
5.1.7 PRESTRESSING TENDONS OF SIXTH SEGMENT.......................................................... 29/69
5.1.8 PRESTRESSING TENDONS OF SEVENTH SEGMENT ................................................... 32/69
5.1.9 PRESTRESSING TENDONS OF EIGHTH SEGMENT....................................................... 35/69

5.2 ELONGATIONS AND PRESTRESSING – CANTILEVER '3E/3W' ....................... 38/69
5.2.1 PRESTRESSIN TENDONS OF HAMMER-HEAD SEGMENT............................................ 38/69
5.2.2 PRESTRESSING TENDONS OF FIRST SEGMENT .......................................................... 42/69
5.2.3 PRESTRESSING TENDONS OF SECOND SEGMENT..................................................... 46/69
5.2.4 PRESTRESSING TENDONS OF THIRD SEGMENT ......................................................... 50/69
5.2.5 PRESTRESSING TENDONS OF FOURTH SEGMENT ..................................................... 54/69
5.2.6 PRESTRESSING TENDONS OF FIFTH SEGMENT .......................................................... 57/69
5.2.7 PRESTRESSING TENDONS OF SIXTH SEGMENT.......................................................... 60/69
5.2.8 PRESTRESSING TENDONS OF SEVENTH SEGMENT .................................................. 63/69
5.2.9 PRESTRESSING TENDONS OF EIGHTH SEGMENT....................................................... 66/69

.: PONTING Inženirski biro d.o.o. .:. Strossmayerjeva 28 .:. 2000 Maribor .:. Slovenija :.

1.0 GENERAL

Structural design of the bridge
The Giborim Highway Bridge is 204 m long and is designed as one braking unit with the following
system (static) spans:

57.0 + 90.0 + 57.0 = 204.0 m

and the pier height from 19.22 to 28.0 m.

The bridge consists of two separated superstructures. The piers of supports 2 and 3 are rigid
conected with the superstructure without using the structural bearings, on supports 1 and 4 the
superstructure is connected to the abutments by uni-directional movable sliding bearings.

The superstructure consists of 2 longitudinally pre-stressed concrete boxes of the width 6.0 m and
variable height from 2.5 m in the span to 5.00 m above the intermediate supports. The width of the
east superstructure vary from 12.5 m to 14.088 m, while the width of the west superstructure is
constant and is 11.0 m.

Superstructure construction technology – Balanced cantilvere construction
The superstructures will be constructed by the technology of balanced cantilever construction,
which is performed in the following main phases:

first the pier hammer-heads of the superstructure in the length of 7.5 m are executed;
the pier hammer-heads are executed on the steel scaffold, assembled under the piers and
lifted with cranes to the required height where they are fixed to the pier;
after fixing the outer and inner formwork the reinforcement is placed, followed by concreting
and pre-stressing.

Concreting of the pier hammer-head will be done in three phases in the following procedure:

casting of the bottom slab;
casting of webs;
casting of the carriageway slab.

When the concrete of the pier hammer-head wins the required concrete strength the tendons are
prestressed, steel scaffold is lowered with crains, demounted and erected again in front of the next
pier and the complete procedure is repeated.

HW GIBORIM Bridge in Israel
PRESTRESSING PROTOCOL FOR CANTILEVER TENDONS Page No.: 1/69


When the pier hammer-heads are casted and prestressed, one pair of form travelers of the bearing
capacity at least 1400 kN are mounted and individual concrete segments of the length from 4.0 to
5.13 m are executed.

For completion of the cantilever tables it is necessary to make on each table symmetrically 8
segments. According to the schedule first the cantilever table above the support 2 and after that the
cantilever table above the support 3 will be constructed.

Post – tensioning system used for prestressing tendons
For the prestressing of the Giborim bridge superstructure, the 'DYWIDAG Bonded Post-Tensioning
System' is used.

During balanced cantilever construction, after the last – eighth segment is casted, each cantilever
table of superstructure is prestressed with a total of 26 cantilever tendons.

All tendons are quality of 1,670/1,860 N/mm 2 and prestressed with the initial prestressing force
P m0 = 3,700.00 kN, what is approximately about 70% of the ultimate strength.

Several post-tensioning tendon consists 19 strands with cross sectional area of 150 mm 2 which
providing very low relaxation (less then 2.5% after 1,000 h at 0.7 x ultimate strength f pk and less
then 7.5% at infinite time).

The post-tensioned tendons of the first three segments are stressed like 'one–end stressing', while
the following segments of the superstructure are stressed like 'both–ends stressing'.

The 'Elaborate of stressing post-tensioning tendons' contains input–data of post-tensioning
system, stressing protocol, conditions of minimum concrete strength at time of prestressing
and calculated elongations for all cantilever tendons of each individual segment.

2.0 ACTIONS AT PRESTRESSING
In the frame of post-tensioning procedure, contractor also obligates to consider all valid
technical regulations, standards and recommendations for the prestressing.

All equipment which used for prestressing must be attested and jack also calibrated. The pressure
gauge and jack must be calibrated together and remain together as a unit throughout all stressing
operations. In the case that there is more than 2% difference between the jack accuracy and the
calibration chart, the jack must not be used for prestressing of post-tensioning tendons and should
be recalibrated before re-use for prestressing.



CONDITIONS FOR CONCRETE STRENGTH AT TIME OF PRESTRESSING

Tendons can be pre-stressed when the concrete reaches the specified minimum compressive
strength prescribed in the table below, but not early than 2.5 days (60 hours) after casting of the
individual segment !

Superstructure: Concrete GRADE 50 – in accordance to BS5400
C40/50 (f ck,cyl /f ck,cube ) – in accordance to EC

f cmj,cyl … mean concrete strength on cylinder with diameter of 150mm and hight of 300mm
at time of prestressing
f cmj,cube … mean concrete strength on cube with the edge length of 150mm at time of prestressing

1st condition:
age of concrete segment T > 2.5 days (60 hours)
at prestressing

** nd
fcmj,cyl (d150/h300), t=2.5 ≥ 35.0 N/mm2
2 condition:
Mean concrete strength at the time
fcmj,cube (150/150/150), t=2.5 ≥ 43.0 N/mm2
of the full prestressing force
fcmj,cube (100/100/100), t=2.5 ≥ 45.5 N/mm2

The mean concrete strength shall be verified by means of at
3rd condition:
least three specimens, which shall be stored under the same
maximum deviation of the
conditions as the concrete member, with the individual
individual values
values of specimens not differ more than 5%

** Note refer to 2 nd condition:
The mean concrete strength at the time of prestressing is determined in accordance to European Technical
Approval – ETA-06/0022 for DYWIDAG Post-Tensioning system, issued by 'DIBT – Deutches Institut für
Bautechnik'

Stressing record
All stressing operations has to be recorded for several tendon and elongation is measured and
compared with the calculated value.

If during tensioning the difference between measured and calculated elongation is
more than 15% of the calculated value (ETA-06/0022, page 14 – paragraph 4.2.6.2)
then the engineer shall be informed and causes shall be found !



3.0 GROUTING OF POST-TENSIONING TENDONS
Grouting of post-tensioning tendons of superstructure has to be provided as soon as
possible after post-tensioning tendons are installed and prestressed.

The durability of post-tensioned construction depends mainly on the success of the grouting
operation. The hardened cement grout provides bond between concrete and tendons as well as
primary long-term corrosion protection for the prestressing steel.

Base to grouting is that all grout outlets are opened and checked to ensure they are free and clear
of any debris and water. Grouting is always done from an inlet at the lowest point of the tendon
profile; this can be at an initial anchor or at an intermediate low point in the tendon profile.

With regard to the especial importance grouting injection work for ensuring of the durability
and capacity of the prestressed concrete superstructure, there is necessary, grouting
injection work of post-tensioning tendons must be also performed in presence of mandatory
supervisory ingineer.

Grouting should proceed in accordance to an approved Grouting Plan, which also contains
the requirements of the project specification for post-tensioning and grouting works !

Grouting Plan
Project responsibilities regrading the 'Grouting Plan' are:

• the Contractor should prepare and submit a 'Grouting Plan' according to requirements of the
project specification for post-tensioning and grouting;
• the Construction Engineering and Inspection Agency (CEI) should record submittals, review
and notify the Contractor of the acceptability of his proposed 'Grouting Plan'.

Grout
Grout is composed from cement, water and additions. The base material of grout is ordinary
Portland cement, which should not be older than three weeks and it should be stored indoors
(unopened container) also protected against humidity. The addition of 'micro-silica' also improves
resistance to chloride penetration because the particles help fill the interstices between hydrated
cementitious grains thus reducing the permeability.

The water-cementitious material ratio should be limited to a maximum of 0.45 to avoid excessive
water retention and bleed and to optimize the hydration process.



Basic requirements for grout injection of superstructure tendons
Grouting has to be performed according to an approved 'Grouting Plan'. Before starting with grout
injection, it is necessary to perform next actions as follows:

• ducts for tendons must be cleaned by air-blowing and in case it is necessary by water-
washing;
• all grout outlets must be opened and checked to ensure they are free and clear of any debris
and water;
• at each outlet vent and final grout cap, pumping should continue until the consistency of the
pumped grout is equivalent to that being injected at the inlet;
• for normal operations grout should be injected at a pressure of less than 0.52 MPa at the inlet
and the grouting speed should be in the range between 3 m/min and 12 m/min;
• grouting should provides from an inlet at the lowest point of the tendon profile and so long
until all intermediate outlets have been closed and grout free of all slugs of air or water flows
from the last anchor outlet;
• after all outlets have been bled and closed, the pressure should be increased to
approximately 0.52 MPa and held for 2 minutes while the tendon is inspected for any
evidence of leaks and avoid the unintended loss of grout.



4.0 SAFETY AT WORKS
For all procedures, equipment, materials and details that are not speccially quoted, recognized
technical norms, regulations and standards shall be applied.
The main contractor Terre Armee Ltd and his subcontarctors for individula special works as are
prestressing and grouting works are also responsible to organize the works in such a way to
absolutely assure the safety at work and keep all the documentation, required by regulation.

5.0 CANTILEVER BOUNDED POST–TENSIONING TENDONS
For the prestressing of the Giborim bridge superstructure, the 'DYWIDAG Bonded Post-Tensioning
System' is used.

All tendons are quality of 1,670/1,860 N/mm 2 and prestressed with the initial prestressing
force P m0 = 3,700.00 kN, what is approximately about 70% of the ultimate strength.

Several post-tensioning tendon consists 19 strands with cross sectional area of 150 mm 2 which
providing very low relaxation (less then 2.5% after 1,000 h at 0.7 x ultimate strength f pk and less then
7.5% at infinite time).

For the all cantilever tendons the technical data is taken into account in the static calculation as
follows:

• cross-sectional area Ap = 2,850 mm 2
• tendon type 19 − 150 mm 2
• yield strength f p 0.1k = 1,600 N mm 2
• ultimate strength f pk = 1,860 N mm 2
• modulus of elasticity Ep = 195,000 N mm 2
• friction coefficient μ = 0.20
• wobble coefficient k = 0.005 rad m ≅ 0.30 o m
• slip at the anchorages - wedge set = 6 mm
• initial prestressing force Pm 0 = 3,700 kN

The post-tensioned tendons of the first three segments are stressed like 'one–end stressing',
while the other segments of the superstructure are stressed like 'both–ends stressing'.



5.1 ELONGATIONS AND PRESTRESSING – CANTILEVER '2E/2W'
5.1.1 PRESTRESSING TENDONS OF HAMMER-HEAD SEGMENT
At the time when hammer-head segment 2E-HH of table 2E is casted and all conditions
regarding the required mean concrete strength are fulfiled, the next post-tensioning cantilever
tendons are prestressed:

TL1, TR1, TL2, TR2

All tendons of current stage are stressed like 'one–end stressing' (see sketch on next page)
by the following initial prestressing force / f py ≅ 0.7xf pk :

Tendon 19–150 mm 2 (A p = 2850 mm 2 ) is prestressed with P m0 = 3,700 kN … f py = 1298.3 N/mm 2

For stressing of post-tensioning tendons 'Multiplane anchorage MA-6819' is used, because of the
jacking system should be fitted for the current post-tensioning system.

Calculated elongations at prestressing tendons of the hammer-head segment 2E-HH are as
follows in the table below:

Prestressing
Tendon Anchorage Net length Net total tendon elongation
Prestressing force
designation type (m) after all wedge set
(kN)

51.0 – 6.0 =
TL1 8.05
45.0 mm

50.6 – 6.0 =
TR1 8.00 from
MA-6819 44.6 mm
ONE–END 3,700
19–150 mm 2 51.2 – 6.0 =
TL2 8.05 stressing
45.2 mm

51.0 – 6.0 =
TR2 8.00
45.0 mm

Elongation of the prestressing steel in the jack and seating device, which is dependent by
choosing of the post-tensioning system, has to be additionally considered at the total tendon
elongation!

Slip at anchorages of 6mm – wedge set is already taken into account in the static calculation
and the determination of the tendon elongation!



5.1.2 PRESTRESSING TENDONS OF 1 st SEGMENT
At the time when first segments 2E-D1 and 2E-U1 of table 2E are casted and all conditions

TL3, TR3, TL4, TR4

All tendons of current stage are stressed like 'one–end tressing' (see sketch on next page)



Calculated elongations at prestressing tendons of the first segments 2E-D1 and 2E-U1 are as

Prestressing
Prestressing force
(kN)

104.9 – 6.0 =
TL3 16.70
98.9 mm

103.9 – 6.0 =
TR3 16.60 from
MA-6819 97.9 mm
ONE–END 3,700
19–150 mm 2 104.6 – 6.0 =
TL4 16.70 stressing
98.6 mm

104.2 – 6.0 =
TR4 16.60
98.2 mm

elongation!




5.1.3 PRESTRESSING TENDONS OF 2 nd SEGMENT
At the time when second segments 2E-D2 and 2E-U2 of table 2E are casted and all conditions

TL5, TR5, TL6, TR6

All tendons of current stage are stressed like 'one–end stressing' (see sketch on next page)



Calculated elongations at prestressing tendons of the second segments 2E-D2 and 2E-U2 are
as follows in the table below:

Prestressing
Prestressing force
(kN)

171.7 – 6.0 =
TL5 26.90
165.7 mm

170.6 – 6.0 =
TR5 26.75 from
MA-6819 164.6 mm
ONE–END 3,700
19–150 mm 2 169.5 – 6.0 =
TL6 26.90 stressing
163.5 mm

168.4 – 6.0 =
TR6 26.75
162.4 mm

elongation!




5.1.4 PRESTRESSING TENDONS OF 3 rd SEGMENT
At the time when third segments 2E-D3 and 2E-U3 of table 2E are casted and all conditions

TL7, TR7, TL8, TR8

All tendons of current stage are stressed like 'both–ends simultaneous stressing' (see sketch
on next page) by the following initial prestressing force / f py ≅ 0.7xf pk :



Calculated elongations at prestressing tendons of the third segments 2E-D3 and 2E-U3 are as

Prestressing
Prestressing force
(kN)

2 x (116.4 – 6.0) =
TL7 37.20
2 x 110.4 mm

2 x (113.8 – 6.0) =
TR7 36.95 from
MA-6819 2 x 107.8 mm
BOTH–ENDS 3,700
19–150 mm 2 simultaneous 2 x (114.7 – 6.0) =
TL8 37.20 stressing 2 x 108.7 mm

2 x (115.6 – 6.0) =
TR8 36.95
2 x 109.6 mm

elongation!




5.1.5 PRESTRESSING TENDONS OF 4 th SEGMENT
At the time when fourth segments 2E-D4 and 2E-U4 of table 2E are casted and all conditions

TL9, TR9




Calculated elongations at prestressing tendons of the fourth segments 2E-D4 and 2E-U4 are

Prestressing
Prestressing force
(kN)

2 x (144.7 – 6.0) =
TL9 47.30 from
MA-6819 2 x 138.7 mm
BOTH–ENDS 3,700
TR9 46.90 stressing 2 x 137.7 mm

elongation!




At the time when fifth segments 2E-D5 and 2E-U5 of table 2E are casted and all conditions

TL10, TR10




Calculated elongations at prestressing tendons of the fifth segments 2E-D5 and 2E-U5 are as

Prestressing
Prestressing force
(kN)

2 x (176.1 – 6.0) =
TL10 57.45 from
MA-6819 2 x 170.1 mm
BOTH–ENDS 3,700

elongation!




At the time when sixth segments 2E-D6 and 2E-U6 of table are casted and all conditions

TL11, TR11




Calculated elongations at prestressing tendons of the sixth segments 2E-D6 and 2E-U6 are as

Prestressing
Prestressing force
(kN)

2 x (204.1 – 6.0) =
TL11 67.75 from
MA-6819 2 x 198.1 mm
BOTH–ENDS 3,700

elongation!




At the time when seventh segments 2E-D7 and 2E-U7 of table 2E are casted and all conditions

TL12, TR12




Calculated elongations at prestressing tendons of the seventh segments 2E-D7 and 2E-U7 are

Prestressing
Prestressing force
(kN)

2 x (237.2 – 6.0) =
TL12 77.80 from
MA-6819 2 x 231.2 mm
BOTH–ENDS 3,700

elongation!




At the time when eighth segments 2E-D8 and 2E-U8 of table 2E are casted and all conditions

TL13, TR13

on the next page) by the following initial prestressing force / f py ≅ 0.7xf pk :



Calculated elongations at prestressing tendons of the eighth segments 2E-D8 and 2E-U8 are

Prestressing
Prestressing force
(kN)

2 x (261.5 – 6.0) =
TL13 88.20 from
MA-6819 2 x 255.5 mm
BOTH–ENDS 3,700

elongation!




5.2 ELONGATIONS AND PRESTRESSING – CANTILEVER '3E/3W'
5.2.1 PRESTRESSING TENDONS OF HAMMER-HEAD SEGMENT
At the time when hammer-head segment 3E-HH of table 3E is casted and all conditions

TL1, TR1, TL2, TR2

All tendons of current stage are stressed like 'one-end stressing' (see sketch on the next page)



Calculated elongations at prestressing tendons of the hammer-head segment 3E-HH are as

Prestressing
Prestressing force
(kN)

52.3 – 6.0 =
TL1 8.25
46.3 mm

51.1 – 6.0 =
TR1 8.05 from
MA-6819 45.1 mm
ONE–END 3,700
19–150 mm 2 52.7 – 6.0 =
TL2 8.25 stressing
46.7 mm

51.3 – 6.0 =
TR2 8.05
45.3 mm

elongation!




5.2.2 PRESTRESSING TENDONS OF 1 st SEGMENT
At the time when first segments 3E-D1 and 3E-U1 of table 3E are casted and all conditions

TL3, TR3, TL4, TR4




Calculated elongations at prestressing tendons of the first segments 3E-D1 and 3E-U1 are as

Prestressing
Prestressing force
(kN)

106.9 – 6.0 =
TL3 17.10
100.9 mm

105.8 – 6.0 =
TR3 16.80 from
MA-6819 99.8 mm
ONE–END 3,700
19–150 mm 2 107.7 – 6.0 =
TL4 17.10 stressing
101.7 mm

105.0 – 6.0 =
TR4 16.80
99.0 mm

elongation!




5.2.3 PRESTRESSING TENDONS OF 2 nd SEGMENT
At the time when second segments 3E-D2 and 3E-U2 of table 3E are casted and all conditions

TL5, TR5, TL6, TR6




Calculated elongations at prestressing tendons of the second segments 3E-D2 and 3E-U2 are

Prestressing
Prestressing force
(kN)

174.3 – 6.0 =
TL5 27.50
168.3 mm

172.8 – 6.0 =
TR5 27.00 from
MA-6819 166.8 mm
ONE–END 3,700
19–150 mm 2 174.0 – 6.0 =
TL6 27.50 stressing
168.0 mm

169.2 – 6.0 =
TR6 27.00
163.2 mm

elongation!




5.2.4 PRESTRESSING TENDONS OF 3 rd SEGMENT
At the time when third segments 3E-D3 and 3E-U3 of table 3E are casted and all conditions

TL7, TR7, TL8, TR8




Calculated elongations at prestressing tendons of the third segments 3E-D3 and 3E-U3 are as

Prestressing
Prestressing force
(kN)

2 x (119.5 – 6.0) =
TL7 38.05
2 x 113.5 mm

2 x (115.6 – 6.0) =
TR7 37.35 from
MA-6819 2 x 109.6 mm
BOTH–ENDS 3,700
TL8 38.05 stressing 2 x 111.0 mm

2 x (116.4 – 6.0) =
TR8 37.35
2 x 110.4 mm

elongation!




At the time when fourth segments 3E-D4 and 3E-U4 of table 3E are casted and all conditions

TL9, TR9




Calculated elongations at prestressing tendons of the fourth segments 3E-D4 and 3E-U4 are

Prestressing
Prestressing force
(kN)

2 x (147.8 – 6.0) =
TL9 48.45 from
MA-6819 2 x 141.8 mm
BOTH–ENDS 3,700

elongation!




At the time when fifth segments 3E-D5 and 3E-U5 of table 3E are casted and all conditions

TL10, TR10




Calculated elongations at prestressing tendons of the fifth segments 3E-D5 and 3E-U5 are as

Prestressing
Prestressing force
(kN)

2 x (179.0 – 6.0) =
TL10 58.55 from
MA-6819 2 x 173.0 mm
BOTH–ENDS 3,700

elongation!




At the time when sixth segments 3E-D6 and 3E-U6 of table 3E are casted and all conditions

TL11, TR11




Calculated elongations at prestressing tendons of the sixth segments 3E-D6 and 3E-U6 are as

Prestressing
Prestressing force
(kN)

2 x (207.6 – 6.0) =
TL11 69.35 from
MA-6819 2 x 201.6 mm
BOTH–ENDS 3,700

elongation!




At the time when seventh segments 3E-D7 and 3E-U7 of table 3E are casted and all conditions

TL12, TR12





Prestressing
Prestressing force
(kN)

2 x (239.8 – 6.0) =
TL12 79.25 from
MA-6819 2 x 233.8 mm
BOTH–ENDS 3,700

elongation!




At the time when eighth segments 3E-D8 and 3E-U8 of table 3E are casted and all conditions

TL13, TR13





Prestressing
Prestressing force
(kN)

2 x (266.0 – 6.0) =
TL13 90.50 from
MA-6819 2 x 260.0 mm
BOTH–ENDS 3,700

elongation!



Cantilever Tendon Prestressing Protocol for Giborim Highway Bridge

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