new technologies in reinforced concrete
TRANSCRIPT
New Technologies in Reinforced Concrete
Professor Des Bull
Holcim Adjunct Professor in Concrete Design
Department of Civil and Natural Resources
Engineering
University of Canterbury
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Conventional Buildings�pre �1980
� Concrete
� Frames – beams and columns
� Walls
� Combination of walls and frames
� Lack on modern seismic engineering
� Little “toughness” or “resilience”
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Harcourts, Madras St �pre �1980s
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22 Feb 2011Harcourts, Madras St
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Aftershock June 13 2011
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Aftershock June 13 2011
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Aftershock June 13 2011
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Conventional Buildings�post 1980
� Concrete
� Frames – beams and columns
� Walls
� Combination of walls and frames
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Desirable post�elastic mechanisms in moment resisting frames
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Critical Structural Issues
� Conventional Beams:
� Yield or go plastic
� Elongate under cyclic loading from earthquake
� Concrete worst
� Then steel
� Then timber (in connection hardware)
� Loss of floor support
� Loss of load path across
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Plastic Hinge in a RC Beam
� Conventional Beams:
� Yield or go plastic
� Elongate under cyclic loading from earthquake
UoC Test
J Matthews
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Elongation of the beams –push the columns
� Loss of connection: floor , supports
? ?
Matthews et al 2008
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Clarendon,
Chch 2011
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Clarendon, 1987
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N�W corner column
Corner pushed
out
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UoC testing Corner column � top view
J Matthews
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Clarendon
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Clarendon
� Middle bay
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UoC Testing –Partial Collapse of the first h/c unit
J Matthews
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UoC testing - Total Collapse of theFloor
Inte
rsto
rey d
rift (
%)
Inte
rsto
rey d
rift (
%)
1.0 1.0
2.5 2.5
3.5
3.5
1.0 1.0
2.0 2.0
0 0
Inte
rsto
rey d
rift
(%
)
0.5
2.5
0.5
2.5
0
J Matthews
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Post�tensioned Frames & Walls
� PREcast Seismic Structural Systems (PRESSS)
� Japan & USA research programme
� Beams and columns
� Walls
� Tested San Diego 1995
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Slab
Slab
Pivot
BeamColumn
Pivot Slab
BeamColumn
Pivot
BeamColumn
EQ EQ
Pivot or hinge detail
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PREcast Seismic Structural Systems (PRESSS)
UT�GAP connection
Palmieri, Saqan et al.
1996 TCY gap connection
in PRESSS five�storey frame
Nakaki et al., 1999
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Early Japanese reinforced concrete slotted beam (1999)
Ohkubo, Matsuoka et al. 1999
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Conventional concrete frame
� Fracture of main bars
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Slotted Beams & “Non�tearing” floors
� New configurations of typical building materials
� At slab level – beam pivots – like a small hinge
� Very little damage to the floors – doesn’t “tear”.
� Structural Steel and Concrete options
� Timber will work too.
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The Non�Tearing Floor System
BeamColu
mn
Top Hinge
Beam gap
BeamColu
mn Single crack across slab
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Slotted reinforced concrete beam
E Au 2010� FRST “Future Buildings” Programme
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Accommodation of rotation via opening and closing of slot
(a) Positive (gap opening) moment (b) Negative (gap closing) moment
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Slotted Beam
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Start of TestSlotted Beam
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2.0 % DriftSlotted Beam
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3.5 % DriftSlotted Beam
inside
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EoT 4.5% DriftSlotted Beam
Steel tube % � PVC plastic tube % X
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1.0 % DriftSlotted Beam
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2.0 % DriftSlotted Beam
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3.5 % Drift
Top of beam and floor
Conventional Frame
post % 2004
Slotted Beam
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EoT 4.5 % DriftSlotted Beam
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Conventional RC Frame
J Matthews
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2 Storey, “Non�tearing” Precast Concrete Floor / slotted beams
C Muir
et al
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2 Storey, “Non�tearing” Precast Concrete Floor / slotted beams
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� Lower damage than would be expected in a monolithic structure
Slotted Beam at ULS Monolithic Beam at ULS (MacPherson, 2005)
2 Storey, “Non�tearing” Precast Concrete Floor / slotted beams
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46Slotted system floor at ULS Monolithic system floor at
ULS (Lindsay, 2004)
2 Storey, “Non�tearing” Precast Concrete Floor / slotted beams
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ResultsResults
Exterior joint strain penetration Interior joint strain penetration
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Replaceable external mild steel energy dissipaters
� Instead of internal mild steel bars
� Very hard to repair
Pampanin (2005) and Pampanin, Amaris, Akguzel, and Palermo (2006)
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Non�tearing floor connection detailsVariations on the Concept
� “self,centring”
Two�storey,
one�bay
frame tested
Amaris et al., 2008
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Alternative solutions of steel shear corbel/bracket
“Hercules” systems,
proprietary of B.S. Italia srl
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Walls
� Conventional
� Damaged and costly to repair, if possible.
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Grand Chancellor
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123 Victoria St
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New Technologies –rocking wall
Gravity / post%tensioning Gravity / post%tensioning
Restoring
force
Earthquake
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Rocking walls: post�tensioned, bar dampers and viscous dampers
(c) Reinforcement,
confinement and steel
bracket details
(b) Connection
detail
(a) As�built post�
tensioned wall
Marriott et al 2008
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New Technologies in Reinforced Concrete
� Thank you.
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