cable stay bridge construction at bardhman using larsa and lusas four dimensional models by rajesh...

CABLE STAYED BRIDGE AT BARDHAMAN

DESIGN SIMULATION BY LARSA AND

CONSTRUCTION STAGE ANALYSIS ALONGWITH GEOMETRY CONTROL BY LUSAS

Rajesh Prasad,Chief Project Manager M,RVNL Kolkata

Construction stage analysis of Cable Stayed Bridge with total length 188.431 m for ROB at Bardhaman Yard is presented here. The superstructure carries 7.5m carriageway and 1.5 m wide footpath on each side.

DECK Geometry:Total Length of the Bridge : 188.431 mCP1 to P1 (Steel composite deck) : 124.163 mP1 to CP2 (RCC Deck) : 64.265 mNumber of Lanes in each Direction : 2Width of bridge deck for main span : 27.7 mWidth of bridge deck for back span : 28.2 mFootpath : 1.5 m on both sidesCross Slope : 2 %

INTRODUCTION

GENERAL ARRANGEMENT

Plan & Elevation of the Bridge

GENERAL ARRANGEMENT

Cross section of the pylon

GENERAL ARRANGEMENT

Cross section of Main Span

Cross section of Back Span

In Lara4D we have simulated this construction stages so as to get more realistic analysis. As cable elements have been used which are nonlinear in nature, nonlinear analysis has been carried out at each stage.

In Larsa4D, for steel we provided following material property:

• E = 2 x108 KN/m2

• Density = 7850 Kg/m

• Shear Modulus = 7.88 x107 KN/m2

• Poisson Ratio = 0.3

Transverse section showing components of Back Span (64.266m)

65mm WEARING COAT

Transverse section showing components of Back Span (124.163m)

65mm WEARING COAT

In Larsa 4D these construction stages are simulated so as to get more realistic analysis. As cable elements have been used which are nonlinear in nature, nonlinear analysis is carried out at each stage. The initial structure has been kept with a pre-camber such that after complete construction, the deflection brings the structure to desired finish level.

Fundamental period of vibration of the structure is calculated by creating a 3D model of the structure and carrying out its modal analysis in STAAD Pro V8i/ Midas Civil/ Larsa4D.

Stage 16•Max moment in Pylon. Utilization ratio <1

Bending Moment diagram (Dead Load + SIDL)

Stage 16•Max moment in Pylon. Utilization ratio <1 Max. deflection is 208 mm (with

lane reduction it will become 166mm)

Bending Moment diagram (Two Tracks of 70R wheeled)

NATURAL VIBRATIONAL MODE SHAPE-2 (FREQUENCY = 0.66HZ & T = 1.520 SEC)

Analysis Model

• Analysis has been done using finite element analysis software

LUSAS.

• Deck is modeled as grillage of longitudinal and transverse members.

• Deck is integral at P1 and CP2. At CP1 pin support with longitudinal

free movement is used representing the Guided PTFE bearings.

• At P1 and CP2, elastic spring supports representing the pile

stiffness are used.

CABLES

PYLON

PILECAP AND PILE

TEMPORARY SUPPORTS

PIN SUPPORT

LUSAS model of the Bridge

Analysis Model

Grillage of Main Span

Grillage of Back Span

Analysis Model

• Transverse beams are modeled with steel composite properties.

• RCC girders and slabs are modeled as beam elements with

appropriate width and depth as per their spacings.

Analysis Model

• At pylon location and at the end on anchor span deck is integrated with

substructure. So the substructure is also modeled as part of grillage.

• The wall is divided in to longitudinal (vertical) and transverse members.

• The pile cap is modeled along with spring supports with the stiffness of

piles.

• Pylon is represented using beam elements.

• Cables are modeled as 3D-bar elements which exhibits the axial

stiffness in all the three orthogonal directions.

Analysis Model

Analysis Model

Isometric View of the model

Analysis Model

Rendered View of the model

SECTION PROPERTIES

Sr no Component C/S Aream2

M.I. Y-Ym4

M.I. Z-Zm4

1 Longitudinal beam MG1 0.1985 0.06506 0.02084

2 Longitudinal beam MG2 0.20134 0.11369 0.05244

3 Central pylon PL1 0.44 0.41537 0.29487

4 Side pylon PL2 0.3536 0.33657 0.23929

5 Tie Beam 0.0975 0.01546 0.01546

6 RCC side beam 4.5 2.34375 1.215

7 RCC central beam 5 2.60417 1.66667

SECTION PROPERTIES

Sr no Component C/S Aream2

M.I. Y-Ym4

M.I. Z-Zm4

8 Steel cross girder with 4.0m wide deck-End 1 0.20611 0.01292 0.00742

Steel cross girder with 4.0m wide deck-End 2 0.1614 0.0073 0.00572

9 Steel cross girder with 3.5m wide deck-End 1 0.18424 0.01264 0.00507

Steel cross girder with 3.5m wide deck-End 2 0.14478 0.00714 0.00393

10 Steel cross girder with 3.0m wide deck-End 1 0.16236 0.01231 0.0033

Steel cross girder with 3.0m wide deck-End 2 0.12815 0.00696 0.00258

11 Steel cross girder with 2.08m wide deck-End 1 0.12218 0.0115 0.0013

Steel cross girder with 2.08m wide deck-End 2 0.09761 0.00649 0.00106

12 Steel cross girder with 1.58m wide deck-End 1 0.1003 0.01086 0.00073

Steel cross girder with 1.58m wide deck-End 2 0.08099 0.00611 0.00063

Cable No

No of Strands

C/s Area (Sq.m)

6001 22 0.0033

6002 22 0.0033

6003 22 0.0033

6004 22 0.0033

6005 22 0.0033

6006 22 0.0033

6007 31 0.0047

6008 31 0.0047

6009 31 0.0047

6010 31 0.0047

6011 31 0.0047

6012 31 0.0047

6013 31 0.0047

6014 31 0.0047

6015 31 0.0047

6016 31 0.0047

6017 31 0.0047

6018 31 0.0047

SECTION PROPERTIESCable

NoNo of

StrandsC/s Area (Sq.m)

7001 73 0.011

7002 73 0.011

7003 73 0.011

7004 61 0.0092

7005 61 0.0092

7006 61 0.0092

7007 61 0.0092

7008 61 0.0092

7009 61 0.0092

7010 85 0.0128

7011 85 0.0128

7012 73 0.011

7013 73 0.011

7014 73 0.011

7015 73 0.011

7016 73 0.011

7017 73 0.011

7018 73 0.011

MATERIAL PROPERTIES - concrete

• CEB-FIP Model 1990 which is widely acceptable and available in LUSAS

is used to represent the concrete properties with age effect .

• Compressive strength of concrete varies with time is represented as

• fcm(t) = fcm exp(s(1-(28/t)^0.5))

• In above, assumed s = 0.25 (FOR NORMAL CEMENT CONCRETE )

• Concrete strength required is 50MPa (cube) = 40 MPa (cylindrical).

• Ec = 2.15E4 x (fcm/10)(1/3) = 34129000 kN/m2.

MATERIAL PROPERTIES - concrete

• Young’s modulus = 34129000 kN/m2.

• Poison ratio = 0.15

• Density = 2.548 t/m3

• Coefficient of thermal expansion = 0.000012

• Comp. strength = 40000 kN/m2.

• Relative humidity = 70%

• Nominal size = 2Ac/U

MATERIAL PROPERTIES – steel

• Young’s modulus = 200000000 kN/m2.

• Poison ratio = 0.3

• Density = 7.85 t/m3.

• Coefficient of thermal expansion= 0.000012

SUPPORT CONDITION

• Pylon P1 and Pier CP2 are modelled as pilecap with spring

supports of having stiffness of pile.

• At pier CP1, pin support is assumed at bearing level. So only

vertical and transverse translations are restrained and other

displacements are allowed to be free.

• Temporary supports with their corresponding stiffnesses are

assigned to rear concrete deck. These supports are modelled

as "Compression only" spring supports and will be ineffective

when the deck lifts off.

LOADINGS

• Self weight of decks is applied as body force to longitudinal

members, and the weight of cross girder is applied as UDL on

corresponding member.

• The weight of steel stiffeners, diaphragms are precisely considered

and their respective loading locations are used. To account the

weight of evenly distributed stiffeners/studs, material density is

modified appropriately.

• The following table and figure shows a typical 12m segment of

main girder along with the DL considered.

LOADINGS

DL considerations for MG2:

DL considerations for MG1:

SR. Pylon Total WT Consideration forNO. (kN) Model

1 PL1 3115 Density Modified to 13.23 T/m3

2 PL2 5070 Density Modified to 13.34 T/m3

• The weight of pylon segments are also considered according to

the detail drawings by appropriately modifying material density.

DL considerations for Pylon:

• The self weight of DEC

considered for analysis is

applied as four point loads.

To account for the weight of

rails etc., the weight of DEC

has been increased

accordingly (7.6% for front

and rear support and 25.4 %

for CW trolley). Hence the

total weight of DEC

considered is 1806 kN.

DL considerations for Deck Erection Crane (DEC):

• To account for the weight of cable installation equipments and

strand coils, an additional 24T is considered as below.

DL considerations for Cable Installation Equipments & Strand coils etc:

• For each of the six material trolley rails, 1kN/m load is assumed.

SIDL Consideration

• Referring to CES Design report, Following SIDL has been considered.– For crash barrier:1.946 kN/m2 (Applied to total width of

25.7 m)– For wearing coat: 1.43 kN/m2 (Applied to total carriage way

width)

Construction stages

• Load case 1 : Casting of RCC wall at P1 and CP2 is considered to be complete.

• Load case 2 : Casting of RCC beam & slab between P1 and CP1.(DL is assigned. )

• Load case 3 : Erection of steel pylon. (Gravity is assigned to erected pylon )• Load case 4 : Activation and stressing of Backspan cables 6010 & 7010• Load case 5 : Erection of 1st panel.• Load case 6 : Activation and stressing of cables 6009, 7009.• Load case 7 : Panel 1 Green Concrete Load (DL is applied as UDL on CG)• Load case 8 : Activation of Deck on 1st panel.• Load case 9 : Erection of DEC.

Construction stages

• Load case 10 : Activation and stressing of Back span cables 6011 & 7011• Load case 11 : DEC moved for 2nd panel.• Load case 12 : Erection of 2nd panel.• Load case 13 : Activation and stressing of cables 6008, 7008.• Load case 14 : Panel 2 Green Concrete Load (DL is applied as UDL on CG)• Load case 15 : Activation of Deck on 2nd panel.• Load cases16 to 62: Load cases 10 to 15 described above are repeated in

sequence for erection of panel 3 onwards till completion of the entire deck i.e panel 10.

• Load case 62 : Activation of Deck on 10th panel.• Load case 63 : Remove DEC• Load case 64 : Crash Barrier load is applied.• Load case 65 : Second Stage Stressing• Load case 66 : Temporary back span supports removed• Load case 67 : Wearing Coat load is applied.

Analysis and Design checks

• Considering the above stages, analysis has been carried out. Analysis steps have been described in detail in our design note No 8160/E/DN-01-R2.

• Design forces and the stress checks are presented in our design Note no 8160/E/DN-03-R1.

• Theoretical profile of the deck is presented in drawing no 8161/E/DD-02 to 13.

• Few suggestions are received from DDC and are incorporated in the analysis. The revised details and the entire set of the camber drawings will be submitted shortly.

DEFLECTION COMPARISON SL. No. Description of stage Actual Stage

Deflection

Theorotical Stage

Deflection

SL. No. Description of stage Actual Stage Deflection

Theorotical Stage

Deflection1 After Stressing MS-1 6 After casting slab 6009 46 26.95 6009 -28 -15.45 5009 37 42.41 5009 -13 -15.40 7009 49 29.37 7009 -29 -18.312 After casting slab 6008 -55 -45.72 6009 -13 -12.77 5008 -55 -45.93 5009 -14 -12.88 7008 -62 -52.64 7009 -20 -16.30 7 Stressing of BS-3 3 Stressing of BS-2 6009 14 11.67 6009 7 5.92 5009 5 11.69 5009 5 5.81 7009 7 11.50 7009 8 5.00 6008 24 29.864 Erection of panel-2 5008 23 29.91 6009 -40 -28.29 7008 23 30.25 5009 -28 -28.48 8 Restressing of 5008 7009 -37 -27.61 6009 -2 -4.875 Stressing of MS-2 5009 25 23.49 6009 27 30.32 7009 11 5.82 5009 13 30.48 6008 -8 -6.54 7009 27 31.39 5008 83 82.09 6008 142 109.97 7008 22 18.95 5008 136 110.23 9 Erection of panel-3 7008 123 107.92 6009 -35 -30.37

5009 -21 -30.95 7009 -33 -33.92 6008 -96 -111.70 5008 -98 -113.10 7008 -104 -115.71

SURVEY REPORT FORMAT

2 MILLION CYCLE FATIGUE TEST

COMPLETION OF 2 MILLION CYCLE FATIGUE TEST ON 12.05.2014

TENSILE LOAD TEST OF THE STRAND AFTER 2 MILLION CYCLES

1

1

COMMENCEMENT OF FATIGUE TEST SECOND STRAND ON 13.05.2014

44

INSPECTION OF ANCHORAGES

45

CHECKING HARDNESS OF WEDGES

46

ROTATIVE FLEXION TEST (12.05.2014)

47

Trial of Girders at site

Trial of DEC at Fabrication yard

Trolley loaded with Girders/slabs

USFD Checking of Track over Deck

Pylon And Deck Erection For Barddhaman Cable

Stayed ROB

Rail Vikas Nigam Limited

• Pylon erected with High Capacity Tower Crane

• Steel Girders of Composite Deck to be erected with Deck Erection Crane

PYLON SEGMENTS ERECTION WITH TOWER CRANE

ERECTION OF PYLON SEGMENTS

The Team

Placement of Middle girder

Placement of 2 end girder

Placement of 2 cross girder

Placement of 2 more girder (power/traffic block)

Placement of 2 more cross girder (power/traffic block)

Special arrangement of temporary P/F for tightening of HSFG bolts.

Tightening , Checking of HSFG bolts followed by painting at site.

View after placements of all girders for panel no. 3 over track.

View after placements of all girders for panel no. 3 over track.

Placements of Cables, Slabs, Casting deck

Placements of Cables, Slabs, Casting deck

View after placements of all Precast Slab for panel no. 2 over track.

Installation of strand

Survey Reports (Cable 5011)

• HDPE Ducts Preparation• Corrected Table for Temperature• HDPE Duct Welding Table Instructions• Master Strand Preparation Form• Standard Strand Setting Form• Master Strand Setting Form• Isotension Statement• Cable Force Measurement• Anchorage Gird – Under Deck/Outside Pylon• Anchorage Grid – Inside Pylon/Over Deck

Power/Traffic Block Requirement

1/2

Power/Traffic Block Requirement

2/2