Cable Stayed Bridge

World wide cable stayed Bridges

MILAU Bridge

Cable Stayed Bridge at Barddhaman

Brief Structural Design Design Procedure Order Simulation Model Execution Erection

SCOPE

• Length : 825 m• Longest Span 457m• 28.6 m width – 8 lane traffic• Post tensioned concrete box girders• Steel pylon

Vidyasagar Setu

Rajiv Gandhi Sea Link, Mumbai (Bandra Worli Sea Link)

• Cable Stayed Main Bay.• Concrete – steel precast segment at either end.• Length 5.6 Kms.• Longest Span 2 x 250m• Commissioned in 2009.• Costing Rs. 1500 Crores.

• No. of Lanes : 8• Main Span 250 m• Pylon height 165 m.• Costing Rs. 1200 Crores.• Under Construction.

Signature Bridge, Delhi

WORLD WIDE CABLE STAYED BRIDGES

4-LANE CABLE STAYED BRIDGE , BARDDHAMAN

HIGH CAPACITY TOWER CRANE

INTERCONNECTEDTEMPORARY STAIRCASES

4-LANE CABLE STAYED BRIDGE , BARDDHAMAN

Engineers constructed the first cable-stayed bridges in Europe following the close of World War II, but the basic design dates back to the 16th century.

Today, cable-stayed bridges are a popular choice as they offer all the advantages of a suspension bridge but at a lesser cost for spans of 500 to 2,800 feet (152 to 853 meters).

They require less steel cable, are faster to build and incorporate more precast concrete sections.

CABLE STAYED BRIDGE – few facts

Tension

Compression

CABLE STAYED BRIDGE

Basic Principal :- Pylon

Stay Cables

Suspension bridge

Cable-stayed bridge, fan design

CABLE-STAYED BRIDGE

Cable-stayed bridge, harp design

The advantage of cable-stayed bridges lies in the fact that it can be built with any number of towers but for suspension bridges it is normally limited to two towers.

With span length less than 1,000m, suspension bridges require more cables than cable-stayed bridges.

Moreover, cable-stayed bridges possess higher stiffness and display smaller deflections when compared with suspension bridges.

The construction time is longer for suspension bridges.

Single plane or Multiple plane used in cable-stayed bridges?

For one cable plane to be adopted, the requirement of high torsional stiffness of bridge deck is necessary to enhance proper transverse load distribution. Moreover, owing to the higher stiffness of bridge deck to cater for torsional moment, it possesses higher capacity for load spreading. As a result, this avoids significant stress variations in the stay and contributes to low fatigue loading of cables. On the other hand, the use of one cable plane enhances no obstruction of view from either sides of the bridges.

For very wide bridge, three cable planes are normally adopted so as to reduce the transverse bending moment.

Suspension bridges main elements are a pair of main suspension cables stretching over two towers and attached at each end to an anchor buried deep in the ground. Smaller vertical suspender cables are attached to the main cables to support the deck below.

Forces: any load applied to the bridge is transformed into a tension in the main cables which have to be firmly anchored to resist it.

Advantages: Strong and can span long distances such as across rivers.

Disadvantages: Expensive and complex to build

Cable-stayed bridges may appear to be similar to suspension bridges, but in fact they are quite different in principle and in their construction. There are two major classes of cable-stayed bridges: Fan type, which are the most efficient, and Harp or parallel type, which allow more space for the fixings.

Forces: As traffic pushes down on the roadway, the cables, to which the roadway is attached, transfer the load to the towers, putting them in compression. Tension is constantly acting on the cables, which are stretched because they are attached to the roadway.

Advantages: good for medium spans, greater stiffness than the suspension bridge, can be constructed by cantilevering out from the tower, horizontal forces balance so large ground anchorages are not required.

Disadvantages: typically more expensive than other types of bridge, except suspension bridges

MODERN TRENDS IN PRESTRESSED CONCRETE BRIDGES

MILLAU (France)

One of the highest bridge in the world.

The bridge is supported by seven huge pillars.

When the thickness of the platform (14 feet) and the height of the pillars are included, the total height reaches 1102 feet. That is about 50 feet higher than the famous Eiffel Tower.

Construction of this bridge required more than 350,000 tons of concrete and 40,000 tons of steel.

Assembled with the precision of a Swiss watch, this giant was designed to resist winds of up to 130 miles per hour and has cost almost 300 million euros (US$523 million). Built across the mountainous terrain of the Tarn river valley, the 8071-foot long bridge is part of the A-75 freeway.

Seven European countries participated in construction of the bridge, the design of which was the work of the prestigious British architect, Sir Norman Foster, of Manchester, England.

MILLAU, THE HIGHEST BRIDGE IN THE WORLD

One of the highest bridge in the world

8071 feet long

1125 feet high

An engineering challenge has been confronted at Bardhaman in the form of rebuilding an existing distressed ROB (Bridge No-213) on Howrah-Barddhaman route in a very busy yard of Barddhaman Station spanning across 8 platforms and 10 tracks. There are numerous constraints such as the restrictions on maximum height of road surface for connectivity to GT road, minimum clearance from track and 120.913m clear span across tracks. All these constraints resulted in an asymmetrical cable stayed bridge of 188.429m span with part RCC and part composite deck, and RCC piers and part RCC and part steel pylon. The practicality aspect is well incorporated into design by ensuring that the work over electrified tracks and platforms can be done uninterrupted with all safety aspects.

RVNL Kolkata PIU is Implementing Agency

M/s GPT-RANHILL(JV) are main Contractor

M/s Freyssinet are specialized subcontractor

M/s Consulting Engineering Services(India) Pvt. Ltd (JACOB) are the DDC and PMC

IIT Roorkee is the proof consultant

Mathematical Model prepared by Council of Scientific & Industrial Research

Wind Tunnel Test Being Executed By Council of Scientific & Industrial Research

AGENCIES INVOLVED

Clear Span(ABT to ABT): 184.428m Main span length : 124.163 m Side span length : 64.536 m No of cable planes : 3 Type of cable in main span : harp pattern No. of cables in main span : 9 per plane No. of cable per side span : 7 per plane Spacing between cables in main span : 12 m Spacing between the cables in side span : 6.881 m Hight of pylon : 62.329 m Clearance above rail track:6500mm Maximum height of road surface from rail track

level: 7500MM (Road surface to bottommost part of superstructure

= 1000mm)

BARDDHAMAN CABLE STAYED BRIDGE DETAILS

Group-A/ Rajdhani Route

8 Nos of Platforms

Busy Yard with 10 BG tracks

Completely Electrified Section Connected to GT Road on One SIDE WITH

TWO APPROACH ARMS Connected to KATWA-KALNA Road on the

Other Side with Two Approach Arms.

CHALLENGES BEING ENCOUNTERED

Span Length : 123.893m & 64.536m

Bottom of Bridge : 6.5m above highest Rail level

Finished Road Level : 7.5m above highest Rail level

Position : Position of Common Pier-1, Pylonand Common Pier-2 is Fixed

MANDATORY POINTS

• Height of Pylon Towers : 62.329 M

• No of Pylon Towers : 03 nos.

• Total no of Segments in each pylon : 10 nos.

• Maximum weight of pylon segment : 30 MT(Approx)

(Pylon segment will be erected by Tower Crane)

• Capacity of Tower Crane : 32 MT at 19 M Arm.

IMPORTANT FEATURES OF DECK AND PYLON ERECTION

• Length of Cantilever deck : 124.163 Mtr.

• No. of Segment in deck : 11 nos. (1 Segment ~ 12 M)

• Deck Segment will be erected by Launching Girder

• Capacity of Launching Girder : About 75 MT• Approximate time required for Launching main

span 36 Days

IMPORTANT FEATURES OF DECK AND PYLON ERECTION

Pile = 62 nos.1.5 m diameter 35m/25 m long pile (M 35 concrete)

Pile Cap = 28.90 m x 6.70 m for CP1 37.90 m x 10.90 m for pylon 28.90 m x 10.90m for CP2 (each 2500 mm high)

Pier = 27.90 m x 4 m for CP1 28.200m x 2.50 m for pylon 28.200 m x 2 m for CP2 (each 7000 mm high)

Pylon = 3 Nos 2 m x 2.50 m x 54.768 m steel pylon above deck

Back Span deck = 2 Nos. 68.266 m x 10.350 m x 0.75 m deck slab with one no. 68.266 m x 2.500 m x 2 RC beam and two no. 68.266 m x 2.500 m x 1.80 m RC beam

Steel Deck = 1 No. 120.163 m x 2.000 m x 1.210 m (MG-2) 2 Nos. 120.163 m x 2.000 m x 0.690 m (MG1) 60 nos. 10.850 m x 0.45 m (CG1)2 nos. 120.163 m x 12.850 m x 0.25 m thick RCC deck slab.

Salient Quantities Stay Cables = 255 MT Reinforcement: = 1150 MT Structural Steel (E410) = 1720 MT Structural Steel (E250) = 280 MT Concrete M50 Grade: = 1650 Cum for piers, RC beams, deck slabs Concrete M60 Grade = 60 Cum for pedestals

SALIENT QUANTITIES FOR CABLE STAYED BRIDGE

1) Construction of Pile foundation at common pier and pylon location.

2) Setup of fabrication yard for steel.

3) Construction of common pier and concrete portion of pylon.

4) Erection of Temporary trestles to support RCC back span.

5) Cast RCC back span up to common pier-2.

6) Once concrete of back span achieves full strength steel pylons will be erected on top of RCC main beams.

7) 12m panels for the 124m span will be brought in and will be placed and connected with already in place back span with the help of erection tackles.

8) 1st three pair of cables will be anchored at predetermined position of girders and pylons and will be stressed to desired level.

9) RCC deck slab will be cast. ,

10) Once deck slab achieves desired strength subsequent panels (up to 9th panel) will be brought in one by one and will be positioned with the help of erection tackles. Corresponding set of cables will also be installed and stressed and deck slab concreting will be done.

11) Last panel will be erected spanning between 9th panel and common pier-1. Remove Temporary supports.

12) Cast deck slab on top of already erected last panels with shear studs for composite action.

13) Second stage stressing will be done to obtain target deflected shape of the span.

14) Complete miscellaneous work e.g. crash barrier, railing, wearing course, illumination etc

15) Third stage stressing will be done to minimize bending moments.

16) Open to traffic

CONSTRUCTION STAGES

Common Pier 1

Pile : 14 Nos , 1.5 m dia @ 25M length

Pile cap: Length : 28.9 m Width : 6.7 m Height : 2.5 m

Pier : Length : 27.7 m Width : 4 m

Height : 7 m

(Site before execution) (After Construction)

Common Pier-2

Pile : 21 Nos., 1.5m dia @ 25M length

Pile cap: Length : 28.9 m Width : 10.9 m Height : 2.5 m

Pier : Length : 28.2 m Width : 2 m Height : 7 m

(Site before execution) (After Construction)

PYLON

Pile : 27 Nos., 1.5 m dia @ 35 M length

Pile cap: Length : 37.9 m Width : 10.9 m Height : 2.5 m

Pier : Length : 28.2 m Width : 2.5 m Height : 7 m

(Site before execution) (During execution)

CP1 PIER CASTING

FIRST LIFT ON 24.12.12

Common Pier CP1 ( 27.7 m X 4 m X 7 m) Constructed

Construction of Pile Cap(28.9m x 10.9m x 2.5m) at Common Pier-2 in progress

Retaining wall for diversion road near CP2 in progress

BACK SPAN (PYLON TO CP2)

FABRICATION YARD

Fabrication Yard for Structural Steel Work

Fabrication Yard for Structural Steel Work

Diaphragm Walls had to be introduced in the pylon segments to avoid warping and distortion of geometry

Fabrication Yard for Structural Steel Work

PRECAST SLAB CASTING YARD

Diversion Road

BACK SPAN CASTING

• Height of the pylon is dictated by the stability analysis and economics of the bridge. A tall pylon will minimize the compression introduced into the steel deck system, but may increase the length of cable used while a short pylon will introduce undesirable compressive forces into the steel deck structure.

• The cross section is sized for not only strength and deflection requirements, but also to accommodate a stressing and inspection route.

• Height of the pylon above deck has been fixed as 54.768m. Three steel pylon towers (2.5MX2.0M box) connected by with ties and founded on RCC wall of M50 grade (concrete Part of Pylon).

STRUCTURAL DESIGN

• The deck is supported by three planes of cables in a harp shaped arrangement. Each harp of cables will be anchored to the pylon at one end, and at longitudinal girders running along the deck. The deck to abutment connection for the minor span is a fixed connection while the main span has Pot cum PTFE Bearings at abutment.

• The main span is 123.893m composite steel with 250mm concrete deck. The deck of main span consists of three longitudinal steel box girders connected by I-shaped cross girders attached to the lower halves of the main girders to achieve a flush soffit. These cross girders carry concrete slab acting compositely with the help of shear studs.

STRUCTURAL DESIGN

• The main span of the bridge is divided into longitudinal segments- 8nos. of 12m, 1 no. of 10.63m and 1 no. of 10m, 2nos. of 4m each(first one being of concrete cast with main span).

• The minor span (back span) is 64.536m made of RCC with 750MM RCC deck and three longitudinal beams (Girders) supporting the concrete deck slab cast monolithically.

• Parallel strand HT cables (15.7mm dia-7 wire strand) are being used for the bridge. These cables have the advantages of having compact anchor sizes and can be accommodated in a limited space.

STRUCTURAL DESIGN

VIEW OF MODEL OF PROPOSED CABLE STAYED BRIDGE

• All 62 piles of 1.5 m dia (14 at CP1, 27 at Pylon and 21 at CP2)

• Al Three Pile caps of CP1,CP2 & Pylon

• Back span superstructure has been cast.

• Pylon Towers have been erected upto 60M height.

• DEC is under advance stage of manufacture

PROGRESS AT GLANCE

• Height of Steel Pylons: 54.768 M• No. of Pylons : 03 nos.• Total no. of Segments in Each Pylon : 10 nos.• Maximum weight of pylon segment : 30 MT(Approx)

• Pylon segment will be erected by Tower Crane• Capacity of Tower Crane : 32 MT at 40M Arm.

IMPORTANT FEATURES OF DECK AND PYLON ERECTION

• Length of Cantilever deck : 124.163 Mtr.• No. of Segment in deck : 11 nos. (1 Segment ~ 12 M)

• Deck Segment will be erected by Launching Girder

• Capacity of DEC : About 75 MT• Approximate time required for Launching main

span 28 Days

Important Features of Deck and Pylon Erection

PYLON SEGMENTS ERECTION WITH TOWER CRANE

Pylon Kept Outside the Yard for

• Easier Construction

• Back span construction independent of Railway yard

• In case of any derailment in yard, pylon will remain safe.

• General Arrangement Drawings• Inception Report• Design Basis Report• Detailed Design Calculation• Detailed Design Drawing• Detailed working Drawings• Erection Scheme & Drawings

Design Procedure Order

i) Single lane of 70R or Two lane of 70R wheeled

OR

ii) Single lane of 70R or Two lane of 70R Tracked

OR

iii) Two lane class-A or four lane class-A , whichever governs

Impact factor has been calculated based on figure 5 of IRC-6 2010. For steel bridges above 45m it is recommended to take a value 15.4%.

Live Loading

IRC-06 2010

For live load analysis linear model has been created by replacing cable elements with truss elements. At the end of analysis it is ensured that all the cable are in net tension.

Live Load Analysis

For seismic loading modal analysis with response spectrum method has been used. Natural frequency which is equal to First mode is equal to 0.51 Hz and time period T = 1.95 sec. Response spectrum curve has been taken from IRC-06 2010. Damping coefficient of 3% has been adopted for steel structure.

Seismic Load Analysis

In Larsa4D 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

Seismic Load Analysis

NATURAL VIBRATIONAL MODE SHAPE-1 (FREQUENCY = 0.51HZ & T = 1.958 SEC)

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

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)

Based on the preliminary Aerodynamic Studies as stated in Part I Report Submitted by CRRI, the bridge is not susceptible to classical flutter and gallopingBuffeting, Vortex Induced Oscillation- Limited Amplitude OscillationThe Amplitude of vortex induced oscillation is vey low and not likely to cause discomfort to usersUsing Frequency Domain Approach, peak buffeting response was estimated as 0.160m for assumed aerodynamic force coefficients terrain roughness ( plain terrain, surface roughness parameter =0.005m)To obtain the steady state force coefficients for bridge deck (drag, lift and moment coefficient )Repeat the buffeting analysis (if required)

Objective of Wind Tunnel Study

Model Design and Details of Sectional Model

Model Scale : 1: 40 and blockage is about 5.9%Length of model: 1440mm longWidth of model: 692.5mmAspect Ratio ( length to width ratio): 2.08

CLOSED CIRCUIT WIND TUNNEL OF CRRI LOCATED AT GHAZIABAD

Test Section with Size 1.5mx0.5mx2.0m

CONTROL UNIT OF DC MOTOR

BETZ PROJECTION MANOMETER

αw

Lift

Drag

Wind

Angle of Incidence

Moment

( )WDD ACUF αρ 2

2

1=

( )wLL BCUF αρ 2

2

1=

( )wMM CBUF αρ 22

2

1=WIND INDUCED FORCES ON A BRIDGE DECK

Spring Mounted Bridge Deck Model with Three-Component Strain Gauge Balance Used in Wind Tunnel Testing

Strain Measuring System will be used to measure the stains

•Model Design

•Model Fabrication and mounting

•Instrumentation ( pasting of strain guages in three component balance)

•Calibration of Strain guage balance

•Wind tunnel test at different angle of attack, wind speed

Steps involved in Wind Tunnel Testing

•The basic wind speed for design is to be taken as 47m/s at the location of bridge as per the wind given in IS:875 – Part 3 and IRC:6

•The terrain roughness for the bridge design has been taken as TC-I or plain terrain as per IRC:6 and wind forces in the transverse longitudinal and vertical directions have been computed as per IRC:6.

•The peak buffeting response of bridge deck at the location of maximum modal ordinate of the main span at a distance of 76m from the pylon has been estimated as 0.2225m using the frequency domain analysis, when the houly mean wind speed at deck level is 39.6 m/s.

•The max. amplitude of bridge deck due to vortex excitation in the first bending mode is estimated as 5 mm at a wind speed of 5.93 m/s which is very low compared to the deflection due to dead load and live load and is not likely to cause discomfort to users

•The bridge deck is not likely to be susceptible to galloping oscillation in vertical mode and shall flutter in first torsional mode.

•The bridge deck is not susceptible to classical flutter.

CONCLUSION OF WIND TUNNEL TEST

•Due to large spans, there are massive RCC Piers, pile caps and deck.

•Size of the pile cap is as large as 413SQM X2.5M •Size of RCC pier is as large as 111SQMX7M •Volume of Back span Concrete is 2045CUM

•Massive structures of high grade concrete need special precautions for manufacture, transport and placement of concrete and for holding of reinforcement cages for safety of workers.

•Massive Back Span requires a very sturdy staging arrangement which has to support the back span till all the Stay cables are fixed and stressed.

CONCRETE WORK

• The staging arrangement has to be provided in such a way that enough space is left for stressing of cables from the bottom of the Beams. The staging arrangement has been designed with concrete foundation as per Soil Bearing Capacity since about 800MT of staging is to be provided and retained for very long period (about 1 year).

• The shuttering is specially designed to take the load of concrete.

• The reinforcement cages of pile caps and piers are kept secured by erecting the specially designed portals to ensure safety of the workers.

• Such massive concreting jobs of high grade concrete require uninterrupted concreting which is ensured by having alternative batching plant and several truck-mixers ready.

CONCRETE WORK

Paint :- M/s AkzoNobel

Specification :-

Primer – Interzinc 52 – 75 Micron DFT

Intermediate – High Build Epoxy MIO, Intergard 475HS – 125 Micron DFT

Final Coat – Polysiloxan, Interfine 878 – 120 Micron DFT

APPROVED MANUFACTURER OF PAINT

PAINTING SCHEME

• Insulation of catenary wire to be carried out.• Power block of overhead traction system arranged for all

lifts and all activities to be performed near the high voltage conductor.

• Earthing of all steel girders to be carried out.• Proper safety net to be provided beneath the girders.• Safety platform to be provided for bolting connection at

connection location of main and cross girders.• Temporary hand rails are to be provided on top of the

steel girder.• All opening area to be covered with proper platform and

safety net.

SAFETY MEASURES ADOPTED IN ERECTION

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

105

INSPECTION OF ANCHORAGES

106

CHECKING HARDNESS OF WEDGES

107

ROTATIVE FLEXION TEST (12.05.2014)

108

• Required to avoid scaffolding for casting deck slab over I girder-beam(for composite structure) or over PSC girders?

• A small casting yard has been developed for pre-cast slabs. Casting bed is made on flooring made of vitrified tiles to get the best possible finish of the surface which would be visible from bottom.

• A trial assembly is conducted for girders and cross girders and the precast slabs are placed over it. Using stud guns, studs are provided on girders. Once the trial assembly is checked and found satisfactory at fabrication yard, the same is followed at site and deck slab is cast over the pre-cast slabs placed with I girders and cross girders.

PRECAST SLABS

PRE CAST SLAB

The finish of the precast slab is almost mirror finish

PRE CAST SLAB

TRIAL ASSEMBLY AND STUD FIXING

External Stair case provided to reach various locations of Pylon

Stay cables and Continuous check and Control of deflection and Tower crane for feeding material and equipment

Movement of Cantilever form Traveller over busy yard

Video