Floating Bridges

Patrick Clarke, P.E. Floating Bridge & Special Structures ManagerFloating Bridge & Special Structures Manager

Washington State Department of TransportationBridge & Structures Office

Corps of Engineers Field ManualWar Department 1909War Department 1909

Military Pontoon Bridgey g

Hood Canal Transverse Pontoon Option

Bersoysund Floating Bridgey g g

Nordhordland Floating Bridgeg g

Continuous Pontoon Load Sharing

Insert picture of Truss and A-frameInsert picture of Truss and A-frame

4 car train is 370’ long

Continuous Pontoon Load Sharing

Insert picture of Truss and A-frameInsert picture of Truss and A-frame

HCB Suspension Bridge – Main Span = 6600 ft.p g pBack Spans = 1100 ft.Tower Height = 810 ft.

Price = $3.5 to 4.0 billion

Akashi Kaikyo, Japan – Main Span = 6527 ft. (Current World Record)

WEST APPROACHEAST APPROACH

Current Floating Design (Span Length = 7034.5 ft.)

Tacoma Narrows BridgeTacoma Narrows Bridge

H d C l S i B id

Main Span = 6600 ft.Back Spans = 1100 ft.

Comparison of Alternative Bridge

Hood Canal Suspension Bridge Tower Height = 810 ft.Akashi Kaikyo, Japan – Main Span = 6527 ft. (Current World Record)

Comparison of Alternative Bridge Styles at Hood Canal 15

Submerged, Floating, Tension-Leg Tunnel

Homer HadleyHomer Hadley Lacey V. MurrowLacey V. MurrowPontoon Length…5811 ft.Pontoon Length…5811 ft. Pontoon Length…6603 ft.Pontoon Length…6603 ft.

Pontoon width…..…75 ft.

Roadway Width 106 ft

Pontoon width…..…75 ft.

Roadway Width 106 ft

Pontoon Width…….60 ft.

Roadway Width 56 ft

Pontoon Width…….60 ft.

Roadway Width 56 ftRoadway Width.…106 ft.

Max. Lake Depth.…..195 ft.

Roadway Width.…106 ft.

Max. Lake Depth.…..195 ft.

Roadway Width……56 ft.Roadway Width……56 ft.

SR-90

Pontoon Length…….7578 ft.

Pontoon Width 60 ftPontoon Width…………60 ft.

Roadway Width………..54 ft.

Draw Span Opening….200 ft.

Max. Lake Depth……..200 ft.

Evergreen Point at SR-520

Pontoon Length……...7450 ft.

Pontoon Width…………60 ft.

Roadway Width………..30 ft.

Draw Span Opening…..600 ft.

Max. Canal Depth…….330 Ft.

Hood Canal at SR-104

Pontoon Length 360 ftPontoon Length…..360 ft.

Pontoon Width…...95.5 ft.

R d Width 48 ftRoadway Width……48 ft.

Bascule Lift Span…256 ft.

1st Ave. South at SR-99Channel Depth……...35 ft.

Typical Pontoon Layout

Pontoon Roll in Service

SR-520 Floating Bridge & East Approach

Pontoon Layout

West360’ x 75’240’ x 75’ 50’ x 98’

Interim (4 lane) – 10 SSP’s 60’ x 98’

Future (6 + 2 HCT) – 30 additional SSP’s 50’ x 98’

Ultimate (6 lane) – 44 additional SSP’s 50’ x 98’ East

Floating Bridge Designg g g

Construction sites and pontoon launch methods. Large pontoons can weigh 6 000 to 12 000 tons without6,000 to 12,000 tons without superstructure.

Pontoon Outfitting & Moorage sites Pontoon Outfitting & Moorage sites Transport restrictions such as available

draft, locks, and open water transport., , p p Marine vessel navigation requirements. Treatment of roadway runoff.y

Pontoon Construction Site

Pontoon OutfittingPontoon Outfitting

Floating Bridge Designg g g Beam on elastic foundation vertically y

(water buoyancy). Beam on elastic supports horizontally

(anchor cable support)(anchor cable support). 1 Year Storm - Service Level. 100 Year Storm Extreme Event 100 Year Storm - Extreme Event. Marine vessel collision. Allowable Stress Design to control crack Allowable Stress Design to control crack

width (i.e. leakage). Accommodate tidal or lake level Accommodate tidal or lake level

changes.

Construction and Other Design TolerancesDesign Tolerances Theoretical Draft is increased by 4% to y

allow for formwork expansion and other possible construction inaccuracies.Pontoons are designed to accommodate Pontoons are designed to accommodate enough ballast to adjust freeboard by 3 inches. This ballast is to compensate for punplanned increases in pontoon draft.

Balanced floatation to prevent pontoon hogging due to creephogging due to creep.

Corrosion Protection for Lake Washington BridgesWashington Bridges.

1 ½” concrete cover on exterior surface. 3” concrete cover on roadway surface

1 ½” concrete + 1 ½” MC Overlay. 1” concrete cover every where else. Epoxy coated rebar in top matt of

roadway deck onlyroadway deck only. Micro Silica & Fly Ash added to concrete

mixmix. Cathodic protection on anchor cable

system.y

Corrosion Protection for Hood Canal BridgeHood Canal Bridge.

2” concrete cover on exterior surface. 2 1/2” concrete cover on roadway

surface. 1” concrete cover every where else. Epoxy coating of all rebar. Micro Silica & Fly Ash added to concrete

mix. Cathodic protection on anchor cable Cathodic protection on anchor cable

system.

Damage Controlg

Flooding of any two adjacent cells.Flooding of any two adjacent cells. Flooding of all cells across the width of

the pontoon.p Complete separation of the pontoon

structure by a transverse or diagonal y gfracture.

Severing of any one anchor cable.g y Water tight hatches interior & exterior. Bilge alarms & piping.Bilge alarms & piping.

Table 4. Allowable Maximum Motions due to Enviromental Loads

M i Type of Deflection or Motion

Maximum Allowable Value Units

Roll 0 5 degreesRoll 0.5 degrees

Roll Acceleration 2.0 deg./sec.2

ll k d /Roll Jerk 2.5 deg./sec.3

Heave Acceleration 2.0 ft/sec.2

Heave Jerk 2.5 ft/sec.3

Sway Acceleration 2.0 ft/sec.2

Sway Jerk 2.5 ft/sec.3

Archimedes PrinciplepBuoyant Force = Weight of water displaced

Buoyant Force = H2OBuoyant Force = H2O

Buoyant Force

StabilityB.F. = Buoyant ForceC G C t f G itC.G. = Center of Gravity

W&W = Wind and Wave Force

W&W

C.G.C.G.W&W

B.F.

B.F.

STABILITY MEASUREMENTS

¢

M = METACENTER

¢KG = HEIGHT OF CENTER OF GRAVITY ABOVE KEEL

GM = METACENTRIC HEIGHT

BM = METACENTRIC RADIUS FOR SMALL ANGLES OF HEEL

GM

BM

G CENTER OF GRAVITY

7'-0

"FR

EEBO

ARD

G = CENTER OF GRAVITY

B = CENTER OF BUOYANCY11'-0

"DR

AFT

KG

K = KEEL

3.0' 3.

6'

34.0'

40.0

'

BUOYANT FORCE

M

M=1

0.09

'

BUOYANT FORCE

G¢4'

BM=2

2.01

' GM

=

Z

B B' 18.0

'

B=6.

82'

KG=

18.7

4

RIGHTING MOMENT FOR 5° HEEL = 10.09' * SIN(5° ) * 50.7 K/ FT = 44.6 K-FT/ FT ( GZ)

Pontoon Freebody Diagramy g

Stability Check

Stability Check

Anchor Gallery Sectiony

Probabilistic Wind Speedsp

Significant Wave Heightsg g

Node Map for Structural Modelp

HYDROSTATIC FORCES

TENSION

COMPRESSION

0 0 0 4 " MAXIMUM CRACK WIDTH FOR SERVICE CONDITION0 .0 0 4 " MAXIMUM CRACK WIDTH FOR SERVICE CONDITIONBASE ON MAXIMUM STEEL STRESS OF 14 ,0 0 0 ps i

ION

TENSION

FORCES

MPRESSION

WIND & WAVE FOCOMP

TENSION

COMPRESSION

CO

TENSION

0 .0 1" MAXIMUM CRACK WIDTH FOR 10 0 YEAR STORM

ECCENTRICECCENTRICLOADING

DIAGDIAGONALTENSION

R 4

235+

88.8

7

NTOO

N X

233+

08.8

7

233+

36.8

7

POIN

T23

5+60

.87

232+

83.53

ER 5

. 236

+16.

87

ER 6 23

7+30

.00

¢ PI

ERST

A. 2

¢ PO

NST

A. 2

+0.47%+2.76% +0.96% +1.56%

A.P.A.P.A.P. A.P.

STA

. 2

¢ PA

NEL

PA.

P. S

TA. 2

A.P.

STA

. 2

¢ PI

EST

A.

¢ PI

EST

A.

+2%A.P.

M.H.W. +9.4

EAST TRANSITION SPAN @ HIGH WATER

230.0' (70.105) CHANNEL

52.9

'(16

.135)

50.7'

(15.4

53)

EAST TRANSITION SPAN @ HIGH WATER

PIER

5TA

. 236

+16.

87

ER 4

A. 2

35+8

8.87

PIER

6A.

237

+30.

00

ONTO

ON X

A. 2

33+0

8.87

A. 2

32+8

3.53

A. 2

33+3

6.87

POIN

TA.

235

+60.

87

¢ P

STA

¢ PI

EST

A

¢ P

STA

¢ PO

STA.

+2.76%+3.34% +2%

A.P.

A.P.A.P.A.P.

A.P.

STA

A.P.

STA

¢ PA

NEL

A.P.

ST A

+2.23%+4.32%

EAST TRANSITION SPAN @ LOW WATER

M.L.L.W. EL. 0.0

230.0' (70.105) CHANNEL 61.4

'(18

.720)

51.5'

(15.72

3)

Transition Span

36” Dia.20” Dia.

36 Dia.

42” Dia.24” Dia.

4 12 Strand( 5”) P T Tendons in each

A709 GR HPS 70W for top chord, bottom h d l d l d d l

4-12 Strand(.5”) P-T Tendons in each chord.

chord,longitudinal strut and diagonals.

A709 GR HPS 50 W for floor beamsA709 GR HPS 50 W for floor beams.

API 2Y GR 60 for joint cans and A-FrameAPI 2Y GR 60 for joint cans and A Frame.

Truss & A-Frame

Hood Canal Transition Span Truss

Typical Pontoon Construction SequenceSequence

Pontoon Mock-up Projectp j Develop construction sequence Develop and test concrete mix designs in labp g

Strength Elastic modulus Permeability Shrinkage Autogenous shrinkage Creep

Develop thermal control and cure plan Develop concrete forming system Field testing of construction methods and

materials

Testing Methodologyg gy

Focus on paste propertiesocus o paste p ope t es Use LVM coarse & fine aggregates

Use LVM mix design as benchmark Use LVM mix design as benchmark Parameters evaluated:

Chloride permeability Heat of hydrationy Compressive strength Economics Economics

Testing Methodology (cont.)g gy ( )

2 w/cm ratios: 0 33 0 36 2 w/cm ratios: 0.33, 0.36 9 mix designs:

1 B h k (LVM) @ / 0 33 1 Benchmark (LVM) @ w/cm = 0.33 4 @ w/cm = 0.33 4 @ w/cm = 0.36

Ternary bindersy Primary – Portland Cement Secondary – Fly ash Slag Secondary Fly ash, Slag Ternary – Silica Fume, Metakaolin

Concrete Mix Designsg

Cost Analysis (cont.)y ( )Cost Analysis and Rapid Chloride Permeability

14.00

16.00

18.00

350

400

450

Cou

lom

bs

8.00

10.00

12.00

Cost

, $ /

ksi

200

250

300

e Pe

rmea

bilit

y,

2.00

4.00

6.00

C

50

100

150

Rap

id C

hlor

ide

0.00

LVM-1 CFS-2 CFM-3 CSS-4 CSM-5 CFS-6 CFM-7 CSS-8 CSM-90

1 day 2 days 7 days 14 days RCP