Utracon Method statement for PT slabs 15 12 2008
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Transcript of Utracon Method statement for PT slabs 15 12 2008
Method Statement of Utracon Post-Tensioning Systems U T R A C O N
UTRACON STRUCTURAL SYSTEMS PVT LTD
METHOD STATEMENT
CONTENTS
Page
1. General
2. Post Tensioning Systems
3. Materials
4. Design Data for friction 1 elongation calculation
5. Handling and Storage of Materials
6. General Work Procedures
7. Guidelines for Tendon Installation
8. Stressing
9. Grouting
UTRACON STRUCTURAL SYSTEMS PVT LTD Page 2 of 10
Method Statement of Utracon Post-Tensioning Systems
UTRACON STRUCTURAL SYSTEMS PVT LTD Page 3 of 10
UTRACON STRUCTURAL SYSTEMS PVT LTD
APPENDICES
APPENDIX A.1 Details of UPS Anchorage System
APPENDIX A.2 Details of Hydraulic Jacks
APPENDIX A.3 Summary of Stressing Pressure for Jacks
APPENDIX A.4 Samples of Stressing Report and Interpretation of Stressing Reports
APPENDIX A.5 Technical Details of admixture :
APPENDIX A.6 Checklist for Post-Tensioning Works
APPENDIX A.7 Quality Assurance Procedures
Method Statement of Utracon Post-Tensioning Systems
UTRACON STRUCTURAL SYSTEMS PVT LTD Page 8 of 10
8.2 Stressing of Flat Tendons
• The jack shall be carried by hand to the stressing anchorage.
• Connect jack to hydraulic pump with hydraulic hoses.
• Strand shall be inserted to the jack.
• 25% of the stressing force shall be applied to the tendon to remove slack in the strands.
• Mark shall be made to the strands.
• Proceed with the stressing to the full force.
• Measure the distance of the spray mark to the wedge plate. This will reflect the strand’s elongation from 25% to 100% force. ( assume X mm )
• Add the wedge draw-in of 6mm to the X.
• Effective strand’s elongation from 25% to 100% stressing force, Y
• The total elongation (from 0% to 100% force) shall be calculated by extrapolation of the
value Y.
• Compare the full elongation (actual elongation) against the theoretical value.
A sample of the Stressing Report and interpretation of stressing report are shown in Appendix A.4. De-Shuttering at pour strip area can be carried out after completion of concreting in that area and after achievement of required compressive strength.
Unbalance load from the floor under construction to be distributed with calculated spacing of props.
9. Grouting
Grouting shall not commence unless the consultant has approved the stressing result. Preparation for grouting
• Cut the protruding strands (stressing length) to a minimum of 10mm from the wedge plate.
• The anchorage blackouts shall be filled with the approved cementitious material. • The grouting shall be continued after a minimum period of 24 hours of drying of
the patch up. • Prior to grouting, the ducts shall be thoroughly cleaned by oil free compressed
air.
Y = X + 6mm
Total Strand’s Elongation = Y x 100 75
Method Statement of Utracon Post-Tensioning Systems
UTRACON STRUCTURAL SYSTEMS PVT LTD Page 9 of 10
Proposed grout mix
• Cement in standard 50kg package
(Ordinary Portland cement 53 grade)
• Water = 0.45 x 50kg = 22.5 kg = 22.5 litres
• Admixture = 0.2% weight of cement ( 50 kg ) = 100 ml Mixing sequence = water – additive – cement Min mixing time = 3-4 min 9.1 Tests for grouting
• Viscosity
• Compressive strength. 9.2 Viscosity test
• Viscosity test will be executed by means of a flow cone. • Flow time is measured with a stop watch. • It is the measurement of time that the grout takes to completely flow out of the cone. • It is carried out after the 3-4 min minimum mixing time. • The flow time should be between 10 to 25 seconds.
76 mm
191 mm
38 mm
Filled Level
178 mm Ø
12.7 mm Ø
INTERPRETATION OF STRESSING RESULTS
I Check Elongation ( X 1 for 1
Average Deviation per Average Deviation per
within * 8%
Note :
Average Devialion per Average Deviation per pour I over beam section pour I overpeam section
within * 8%
Average Deviation per Average Devialion per
within i 8%
( A ) The Engineer shall be informed and consulted for more thorough investigation and design check.
SAMPLE
Sheet 1
FORM SS60U04 (REV 0 - 01M1102) Page 1 of 1
of 5
--____....__.-_..A --,." ".__,___..~ ---_ _- .----%" * ..D_ --. .......................... I........ .,. . . I. . .
4
TENDON STRESSING REPORT (Multistrand Anchorage - MA)
PROJECT NAME : ABC BUILDING
STOREY : 1ST STOREY JACK NO : CH 4006 - I
BEAM MARK : 1 PBI GAUGENO: 25
TENDON NO: TI STRESSING FORCE : (kN)
TENDON TYPE : 19 s STRESSING PRESSURE :
CASTING DATE : - (MPa)
Gauge Pressure
(Mpa)
0
10
20
30
40
50
62.9
Gauge Pressure
(MP4
0
Measurement mm
- 50 --
105 -- 162 -
220 -
276 - 351 --
Extension mrn
57
55
57
58
56 ---- 75
a L,
Measurement mm
-
P
358
Actual Extension (rnm) Theoretical Extension (mm)
Ex(erlsior1 m m
-------A
-
--
-
A L2
Extension in
X Extension mm
--
.
Date :
Witnessed by :
- 4
354 350
Jack
Comments
--
--
L
RESULT :
+1.14%
-- --
-- --
A Ll, f L2
358
APPENDIX A.4
SUMMARY OF STRESSING RESULTS
BLOCK : WEST AREA : 3RD STOREY
REMARKS:
* Stressing force of 75% UTS was maintained for 15 seconds.
# Tendons were stressed to 80% UTS and maintained for 15 seconds.
The average deviation for the pour is +2.10% which falls within the tolerance of &8%.
Therefore, the result for the whole pour is acceptable.
Tt-IEORECTICAL
EXTENSION
170 - .....
170 - ...............................................
180
180 .........................................................
60 . . . . . . . . . . .
60 .........................................
60 .-..
6 4
90
90
1 7 i
110
ACTUAL
EXTENSION
' 175
180 -. .. .-.--
160
165 - - .. - ...
70 .. - .... -- -- - ---
70
6 5 .......
60
85
90
185
110
BEAM MARK
3PB-1
3PE3-3
3PB-4
UTS - Ultimate Tensile Strength of Strand
c
TENDON MARK
a1 -...
a2 ----- . - .....
b
a - - - - ... -.
b I
b2
c - d
e
f
a
b
DEVIATION
(%)
2.94 ....................
5.88 .............
# -11.11
# -8.33 - .... - ..........................
x 16.67 - ......... -. . . . . .
* 16.67 ............
8.33 ........
-6.25
-5.56
0.00
5.71
0.00
72 1-
AVERAGE
DEVIATION (%)
-0.76
-2.78
6.53
13.89
OVERALL DEVIATION 2.10
