university of communication and transport Assess steel cable stayed bridges in viet nam Prof.Dr. Nguyen Viet Trung Header of Urban Transport Engineering Section university of communication and transport General assessment of steel cable stayed bridge The assessment of cable stayed bridges are carried out by load testing and reality activities. And specially bridge monitoring system are installed to assess that activities bridge.
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university of communication and transport
Assess steel cable stayed bridges in
viet namProf.Dr. Nguyen Viet Trung
Header of Urban Transport Engineering Section
university of communication and transport
General assessment of steel cable stayed bridge
The assessment of cable stayed bridges are carried out by load testing and reality activities.
And specially bridge monitoring system are installed to assess that activities bridge.
university of communication and transport
Contract dated 30th March 2005 on Loading test for Haiphong Binhbridge between CHODAI Co.,LTD and Center of Civil consulting, Research and Experiment – University of Transport and Communications.
-Based on load testing result at site of Binh bridge by Center of Civil consulting, Research and Experiment – University of Transport and Communications and Haiphong bridges Project manegement unit carried out on 15th, 16th August 2005.
-Documents of Binh bridge project.
- Specification for load testing of bridge on highway 22 TCN 243-98
Binh bridge on load testing
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Main bridge (cable stayed bridge)
Measure stress of girder in longitudinal direction under the affect of standing still moving load on bridge
At mid-span sections of main spanAt mid-span sections of Haiphong side span
Measure deflection in vertical direction under the affect of standing still moving load on bridge
At mid-span sections of main spanAt mid-span sections of Haiphong side span
Measure vibration of main griders at middle spansWithout truckWith truck of 40km/h speechWith truck of 60km/h speech
contents of loading test Binh BRIDGE
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Measure stress of bridge desk in longitudinal direction under the affect of standing still moving load on bridge
At mid-span sections of main spanAt mid-span sections of side span
Measure stress in cables under the affect of standing still moving load on bridgeAnchor cable and next to anchor cable at Haiphong side spanMid-cable and next to mid-cable at Haiphong side main span
Measure stress and displacement of head of pylonsMeasure stress under the affect of standing still moving load at foot of pylon
area section (spaced 0.3m apart from pylon door)
Measure displacement of head of pylons:Static horizontal displacement at head of pylons in longitudinal direction under the
affect of standing still moving load on bridge.
Displacement and dynamic stress with load of 40km/h and 60km/h speech.
contents of loading test Binh BRIDGE
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Testing loadTesting load are 24 HUYNDAI trucks (Korean) loading with sand or
bliding stone to ensure the weight of each truck is about 24.03 to 24.98tons (80% of designed load). Detail of real weight of trucks are noted at Appendix.
Sketch of HUYNDAI truck with spacing between axles as follow:
Each truck is located to put the behind axles about 6m away fromthe ahead axles of the following truck.
Loading train is put on spans in different loading sketches to reach adverse loading effects of each of measuring sections.
contents of loading test Binh BRIDGE
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In each of loading sketch, loading lane arrangement as follow:a- At eccentric position at lower stream,b- At center line,c- At eccentric position at upper stream.
Requirement of testing loadAll testing load shall be weighed for load checking (include legal
certification and minutes of checking at site). Testing load shall be arranged in diferent loading cases appropriate
with effects to measure.
contents of loading test Binh BRIDGE
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
Result of stress measurement of main gridersMaximum stress at compress position (the upper edge of steel grider)a. Mid-span section of main span of main griders (stayed-cable bridge)
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
Commentary on stress measurement result in main griders of stayed-cable bridge part:
Stress measurement results under the affect of moving load whichhave been comparative verifyed are all smaller than theoretical calculated numerical values from 3D structural model analysis by MIDAS-Civil software (55.67 to 68.77%). That shows the big safety reserve of loading capacity of main span superstructure.
The maximum stress value by moving load is 443.10kG/cm2, is about 11.36% of permited loading capacity of steel in grider fy = 3900kG/cm2.
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
1 / 11201 / 112092,06%92,06%252,00252,00232,00232,00Middle of main Middle of main spanspan
ffhh /L/LScale %Scale %Calculation value Calculation value MeasuremeMeasurement valuent value
Maximum deflection (mm)Maximum deflection (mm)Cross sectionCross section
Deflection measurement result is appropriated with theoretical analytic result and is smaller than the permitted deflection value of AASHTO which is L/800 = 0.325m.
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
Stress measurement result at foot of pylon (Haiphong side)The maximum stress at foot of pylon (Haiphong side):
85,7585,75%%
14,9514,9512.8212.8279,6079,60%%
14,9514,9511,9011,90Stress Stress kG/cmkG/cm22
Scale Scale %%
CalculatioCalculation valuen value
MeasuremeMeasurement valuent value
Scale Scale %%
CalculatioCalculation valuen value
MeasuremeMeasurement valuent value
Point Point
Foot of pylon at Foot of pylon at lowerstreamlowerstreamFoot of pylon at Foot of pylon at uppstreamuppstreamCross Cross sectionsection
Stress values which were measured at foot of pylon at compress position are smaller than correlative theoretical calculate numeric values and much smaller than compress intensity of pylon’s material.
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
Displacement measurement result of head of pylon (Haiphong side)
101,1101,190,0090,0091,0091,00
Scale %Scale %Calculation valueCalculation valueMeasurement valueMeasurement value
Displacement result of head of pylon (Haiphong side) (mm)Displacement result of head of pylon (Haiphong side) (mm)
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
Vibrate measurement result of pylon of main bridge
0.3020.302Period (sec)Period (sec)
3.3153.315Frequency (Hz)Frequency (Hz)
Door of S9 pylonDoor of S9 pylonPositionPosition
Vibrate measurement result of main griders of main bridge
0.2450.245Period (sec)Period (sec)
4.0824.082Frequency (Hz)Frequency (Hz)
Middle of main spanMiddle of main spanPositionPosition
Vibrate frequency is in normal limitation.
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Result of Loading test Binh BRIDGE
Result of loading test of main bridge (stayed-cable bridge) under the affect of testing load
DifferenceDifferenceWith moving With moving loadload
Without moving Without moving loadloadCablCabl
ee
Frequency and stress values in cables under the affect of testing moving load are not large.
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Result of Loading test Binh BRIDGE
General conclusion
The loading test work of Binh bridge was completed exactly according to the daft which had been come to an agreement between CHODAI CO.,LTD and Center of Civil consulting, Research and Experiment – University of transport and communication.
Preliminary result shows that technical standards such as load capacity, strain stiffness, settlement, pier displacement, head of pylon’s displacement, eigen vibration period are all appropriate with theoretical analysis result and in the permitted limit.
The loading test process did not show any unusal expression to load bearing systems of the bridge.The Binh bridge of Haiphong was contructed appropriate with the design. The testing result shows that the construction has got enough ability for exploitting with design load.
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Result of Loading test Binh BRIDGE
Some commantaries
After taking into exploit, it is expected to carry out the right monitoring, checking, maintenance work for the construction, especially for the main bridge which is the stayed-cable one, by the management agency. Perfect some structure details such as the drainage system, lock of the door of pylons appropriated with design.
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Photos on during Loading test of Binh BRIDGE
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Result of Loading test Binh BRIDGE
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Result of Loading test Binh BRIDGE
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Result of Loading test Binh BRIDGE
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Result of Loading test Binh BRIDGE
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Main bridge (cable stayed bridge)
Measure stress of main girder at 4 sections Section No1: L/4 of beside spanSection No2: L/2 of beside spanSection No3: L/4 of midle spanSection No4: L/2 of midle span
Measure stress of some section of pylonAt the top of pylon No1 (to To Hieu street)At the top of pylon No2 (to Chu Van Thinh street)
Measure stress of some stayed cables: 12 stayed cables with 24 point of measurement
Measure stress of slap beamMeasure stress of transerver
contents of loading test Son la BRIDGE
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contents of loading test Son la BRIDGE
Measure displacement of main gider at 6 sectionsSection No1: L/4 of beside spanSection No2: L/2 of beside spanSection No3: L/4 of midle spanSection No4: L/2 of midle spanAt the top of pylon No1 (to To Hieu street)At the top of pylon No2 (to Chu Van Thinh street)
Measure Displacement and dynamic stress with load of 40km/h and 60km/h speech at Section No4: L/2 of midle span and Section No2:L/2 of beside span
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contents of loading test son la BRIDGE
Measure settlement and Displacement horizontal of top 2 pylons with 3 pionts for each one.
Measure settlement and lifting power at abutment M2 (to Chu Van Thinhstreet with 2 points.
Measure strength of concrete slab, piers, abutments (without destroy)
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Result of Loading test son la BRIDGEResult of loading test of main girder of bridge (stayed-cable bridge) under the affect of testing load
Frequency f (Hz)Frequency f (Hz)1 + 1 + µµyytbtbyyminmin
(mm)(mm)yymaxmax
(mm)(mm)spanspan
Measure Displacement
5.475.47Middle Middle
3.9023.902Beside Beside
Maximum displacement (mm)Maximum displacement (mm)spanspan
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Photos on during Loading test of son la BRIDGE
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Photos on during Loading test of son la BRIDGE
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Photos on during Loading test of son la BRIDGE
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Photos on during Loading test of son la BRIDGE
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summary
1. The cost of material of Steel Cable stayed bridges in countryside in viet nam is cheap, but the cost of construction is expensive.
2. The assessment maintenance difficultly, required knowledge.
3. There are two type steel cable stayed bridges. The first is Dakrong bridge. This is manufactured by vietnam. The stayed cable is best for cable stayed bridges. The cost and engineering is sensible. The second is binhbridge. That is perfect but the cost is very high.
4. The monitoring system for cable stayed bridges in vietnam are developing with all devices for assessment bridges.