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Ontario’s Rapid Installation of Single Span Bridges
Kent Street Overpass and other bridges
on Highway 417 in Ottawa
May 2016
PRESENTATION OVERVIEW
History and existing conditions
Renewal options
Unique design and construction challenges
Lessons learned
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BACKGROUND
Location
History
Existing conditions
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LOCATION
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EXISTING STRUCTURE
WBL Structure EBL Structure
Typical Section
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GENERAL HISTORY
Original EBL and WBL structures built in 1965
Single variable span – variable depth rectangular voided slab
reinforced concrete structures
Rehabilitation in 1985 (new barriers and exp. joints, deck
patch, concrete overlay, w/p pave and substructure repairs)
Curved abutments (R= 67 m and 85m) on steel ‘H’ piles
WB: 4 traffic lanes EB: 3 traffic lanes
AADT of 160,000 (2015)
Table 1: Summary of Existing Girder Range of Variable Span and Depth
Structure Existing Girder No. Span (m) Depth (mm)
HWY 417 EB G1 31.34 1969
G7 23.28 1635
HWY 417 WB G8 23.23 1635
G16 18.87 1245
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STRUCTURE EXISTING CONDITION
Debonding of concrete overlay
Overlay had reached the end of
its useful service life (28 years
old)
Parent concrete questionable
Probable active corrosion in 0%
and 3% of WBL and EBL deck
Chloride content generally below
0.025% threshold
Deck soffit in fair condition
Substructure in fair condition
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RENEWAL OPTION – SCOPE OF WORK
Conventional superstructure rehabilitation
(40 yrs) vs rapid replacement (75 yrs)
Conventional rehabilitation ruled out (90+
years old, unknown conditions, formwork
removal)
Rehabilitation of existing abutments and
wingwalls with concrete refacing,
sacrificial galvanic anode system
Semi-integral conversion and removal of
ballast walls
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SUPERSTRUCTURE ALTERNATIVES
Slab on steel plate girder (800 mm – 1300 mm depth)
Slab on 1250 mm - 1400 deep steel box girder
Slab on 900 mm – 1500 mm deep CPCI girder
Slab on B 800 – B1000 prestressed box girder (side-by-
side or spaced)
Post-tensioned concrete structure
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PREFERRED ALTERNATIVE
Slab-on-steel girder
Shallower structure allows
increasing existing vertical
clearance from 4.54 to 4.79 m
Design and fabricate custom
girders to suit variable spans
Light superstructure –
reduced seismic demand
Uniform behavior achieved
by varying depth/stiffness to
produce more or less equal
deflections at adjacent
girders
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UNIQUE DESIGN AND CONSTRUCTION
CHALLENGES
Unknown ballast wall and bearing seat condition
Ballast wall removal
Semi-integral abutment conversion
Bearing design
Temporary lateral restraint
Structure plan geometry - variable span/depth, skew, curved end
Staging area
SPMT support points
Watermain – rapid demolition
Rapid replacement constraints
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BEARING SEAT ACCESS
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BALLAST WALL REMOVAL
Removal on weekends with rolling
lane closures
Track-mounted circular saw
Stabilization with temporary lateral
restraint
Granular backfill directly against
structure
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SEMI-INTEGRAL ABUTMENT CONVERSION
Pre-rapid lift condition
Final condition
Sawcut and remove ballast
wall in advance of rapid lift
Stabilize structure for skew
effects
Place perforated subdrain and
temporary backfill
Excavate and remove existing
structure
Place Evafoam blocking
Install new structure
Post rapid lift – form and
pump concrete
Place bearing seat overlay
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BEARING DESIGN
Offset new and existing bearings
Adjustable bearing design
Lateral restraint (skewed forces and seismic)
Legend: = existing bearing seat = new bearing seat
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BEARING DESIGN
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TEMPORARY LATERAL RESTRAINT DEVICES
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DECK PLAN GEOMETRY
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STRUCTURE PLAN GEOMETRY
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VARIABLE SPAN/DEPTH STRUCTURE
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BEARING REACTIONS
WBL
EBL
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SHEAR DIAGRAMS
During Transport on SPMT’s
Permanent Position
WBL structure
EBL structure
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BENDING MOMENT DIAGRAMS
During Transport on SPMT’s
Large negative moments due to skew. Additional
reinforcing steel required to prevent cracking of the
deck during rapid lift
Permanent Position
WBL structure
EBL structure
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STAGING AREA
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SPMT SUPPORT POINTS
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RAPID STRUCTURE DEMOLITION
1200 dia. water main presented construction challenges
Contractor movement plan was based on SPMT
configuration with heavier axle loadings
Contractor presented change proposal (later) to carry out
rapid demolition
Avoid travelling over water main with existing structure
New structures are much lighter than existing (420/440
tonnes vs 820/900 tonnes)
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RAPID STRUCTURE DEMOLITION
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RAPID STRUCTURE REPLACEMENT
EBL Structure - 440 tonnes
2 sets of self-propelled
modular transporters
(SPMT’s)
8 axles, 64 wheels
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RAPID STRUCTURE REPLACEMENT
WBL Structure - 420 tonnes
2 sets of self-propelled modular
transporters (SPMT’s)
8 axles, 64 wheels
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RAPID REPLACEMENT
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LESSONS LEARNED
Survey plan is a must (knowledge of existing structure geometry –
ballast wall/bearing seat elevations/dimensions)
Design flexibility – bearings, geometry, existing bearing conditions
Movement plan should be prepared several weeks in advance
(before fabrication) and to be reviewed by designer and owner
Travelling over utilities – let the Contractor design own temporary
methods but designer to ensure feasible methods exist
Make provisions for repair/adjustment of elements that cannot be
inspected before the removal of the existing structure (ballast
walls, abutment seats, etc.)
Coordinate lift procedure with fabrication of steel girders.
(Additional bearing stiffeners were added because the Contractor
adjusted the lift points)
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LESSONS LEARNED
Use road plates under
SPMT travel path,
especially after heavy
rain, it’s 5:00 am, you are
stuck and cannot get a
hold of the SPMT tow
truck
road plate
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ACKNOWLEDGEMENTS
AECON – General Contractor
SARENS – Subcontractor For Rapid Lift Move (Constructability
Review)
MAMMOET – Rapid Lift Specialist (Constructability Review)
McIntosh Perry – Contract Administrator
MMM Design Team – Adriano DiRienzo – P. Eng., Andrew
Krisciunas – P. Eng., Michael Matthews – P. Eng., Gary Greenan
MTO – Dina Miron P. Eng., George Collins, P. Eng. – Structural
Regional Office
MTO – David Glass P. Eng., Chad Manion – Construction (and
Photographs)
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Questions?
https://www.youtube.com/watch?v=FREdt1jPxHA
http://www.cbc.ca/news/canada/ottawa/kent-street-
bridge-replacement-captured-on-video-1.3290421
E-mail contact info:
Dina Miron – [email protected]
Michel Vachon – [email protected]
Kent Street Overpass - time lapse video/media coverage
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