REPAIR AND STRENGTHENING OF REINFORCED CONCRETE COLUMNS AND BEAMS ICRI – International Concrete...
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Transcript of REPAIR AND STRENGTHENING OF REINFORCED CONCRETE COLUMNS AND BEAMS ICRI – International Concrete...
REPAIR AND STRENGTHENING OF REPAIR AND STRENGTHENING OF REINFORCED CONCRETE REINFORCED CONCRETE
COLUMNS AND BEAMSCOLUMNS AND BEAMS
ICRI – International Concrete Repair Institute
Transportation Structures
2010 Fall Convention
Pittsburgh October 20-22
2/83ICRI 2010 – Pittsburgh October 20-22
UHPFRCC
Ultra High Performance Fiber Reinforced Cementitious Composites
-UHPC – Ultra - High Performance Concrete -HPFRCC – High Performance Fiber Reinforced Cementitious Composites -ECC – Engineered Cementitious Composites -HPECCMF – High Performance Engineered Cementitious Composites Multiple Fine Cracks
3/83ICRI 2010 – Pittsburgh October 20-22
UHPFRCC
UHPFRCC
4/83ICRI 2010 – Pittsburgh October 20-22
Jacketing
5/83ICRI 2010 – Pittsburgh October 20-22
Tensile tests according Italian Standard
0 1 2 3 4 5
S tra in [‰ ]
0123456789
1 0111 21 3
Str
ess
[MP
a]L = 330 mm
t = 13 mm
bp = 30 mmt
bpL
Characterization in tension – stress deformation
6/83ICRI 2010 – Pittsburgh October 20-22
Adhesion tests
7/83ICRI 2010 – Pittsburgh October 20-22
Adhesion tests
GF5 Ordinary concrete
8/83ICRI 2010 – Pittsburgh October 20-22
Preparation of the support
9/83ICRI 2010 – Pittsburgh October 20-22
Strengthening of columns
10/83ICRI 2010 – Pittsburgh October 20-22
Existing column
fc=15MPa
11/83ICRI 2010 – Pittsburgh October 20-22
Existing column
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
-500 -250 0 250 500 750 1000 1250 1500 1750 2000
M [kNm]
N[kN]
12/83ICRI 2010 – Pittsburgh October 20-22
Strengthened column
UHPFRC fc=170MPa
fct=11MPa
13/83ICRI 2010 – Pittsburgh October 20-22
Stress distributions
14/83ICRI 2010 – Pittsburgh October 20-22
-500
-400
-300
-200
-100
0
100
200
300
400
500
-1000 0 1000 2000 3000 4000 5000 6000 7000 8000
M [kNm]
N[kN]un-reinf
HPFRC
Strengthened column
15/83ICRI 2010 – Pittsburgh October 20-22
Traditional jacketing
-450
-350
-250
-150
-50
50
150
250
350
450
-1500 -500 500 1500 2500 3500 4500 5500
M [kNm]
N[kN]
R/C
un-reinf
fc=30MPa
16/83ICRI 2010 – Pittsburgh October 20-22
-150
-125
-100
-75
-50
-25
0
25
50
75
100
125
150
-1000 -500 0 500 1000 1500 2000 2500
M [kNm]
N[kN]
un-reinf
FRP_LT
FRP_L
Strengthening with FRP
17/83ICRI 2010 – Pittsburgh October 20-22
Comparison
-500
-400
-300
-200
-100
0
100
200
300
400
500
-1500 -500 500 1500 2500 3500 4500 5500 6500 7500 8500
M [kNm]
N[kN]
HPFRC
R/C
FRP_LT
un-reinf
18/83ICRI 2010 – Pittsburgh October 20-22
Seismic retrofitting
19/83ICRI 2010 – Pittsburgh October 20-22
School building in Zagarolo
20/83ICRI 2010 – Pittsburgh October 20-22
In situ tests fc=11MPa
21/83ICRI 2010 – Pittsburgh October 20-22
Strengthening with GF5 UHPFRCC
UHPFRCC130MPa
40 mm
22/83ICRI 2010 – Pittsburgh October 20-22
Column tests
23/83ICRI 2010 – Pittsburgh October 20-22
Load history
24/83ICRI 2010 – Pittsburgh October 20-22
Drift [%]0-7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7
-200
-150
-100
-50
0
50
100
150
200
-140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140Displacement [mm]
Ho
rizo
nta
l L
oad
[kN
]
Results
25/83ICRI 2010 – Pittsburgh October 20-22
Results
26/83ICRI 2010 – Pittsburgh October 20-22
Numerical prediction
27/83ICRI 2010 – Pittsburgh October 20-22
Joint tests
28/83ICRI 2010 – Pittsburgh October 20-22
Load history
29/83ICRI 2010 – Pittsburgh October 20-22
30/83ICRI 2010 – Pittsburgh October 20-22
31/83ICRI 2010 – Pittsburgh October 20-22
32/83ICRI 2010 – Pittsburgh October 20-22
33/83ICRI 2010 – Pittsburgh October 20-22
34/83ICRI 2010 – Pittsburgh October 20-22
Jobsite application
35/83ICRI 2010 – Pittsburgh October 20-22
Jobsite application
36/83ICRI 2010 – Pittsburgh October 20-22
FASE 4:realizzazione della seconda parte di cassero
fino all'estradosso del solaio esistente
cassero ancorato sul precedente getto di Refor-tec GF5 ST-HS
solaio
carotaggi
40 cm
40 cm
40 cm
40 cm
staffature di rinforzoin acciaio
DETTAGLIO A
Jobsite application
37/83ICRI 2010 – Pittsburgh October 20-22
forotavola chiodata
per evitare la fuoriuscitadi materiale
CASS
ERO
CLS
PILA
STRO
Jobsite application
38/83ICRI 2010 – Pittsburgh October 20-22
Beam strengthening
39/83ICRI 2010 – Pittsburgh October 20-22
4.0
4.0
HPFRCC
cm
cm
Jacketing
40/83ICRI 2010 – Pittsburgh October 20-22
3 BEAMS: ASR, BCR, ACR (300x500x4550 mm)
ASR: RC beam with 2 rebars having a 16mm diameter 0.3%)
BCR: concrete beam without rebars + jacketing in HPFRCC
ACR: RC beam ( 0.3%) + jacketing in HPFRCC
Experimental program
41/83ICRI 2010 – Pittsburgh October 20-22
0 20 40 60 80D isp lacem ent [m m ]
0
100
200
300
400
500 Load [kN ]
Results
42/83ICRI 2010 – Pittsburgh October 20-22
Results
0 4 8 12 16 20D isp lacem ent [m m ]
0
100
200
300 Load [kN ]
S LS
43/83ICRI 2010 – Pittsburgh October 20-22
Sandblasting of the beams
Jobsite application
44/83ICRI 2010 – Pittsburgh October 20-22
Waterjetting
The pouring
Jobsite application
45/83ICRI 2010 – Pittsburgh October 20-22
Thixotropic UHPFRCC application
Jobsite application
46/83ICRI 2010 – Pittsburgh October 20-22
Protection of material with a thermal jacket
Jobsite application
47/83ICRI 2010 – Pittsburgh October 20-22
First example of application:
PROJECT OF SEISMIC ADJUSTMENT OF THE “HOSPITAL COTUGNO” OF BARI
Object:Hospital Cotugno
Place:Bari
Repair:Seismic rehabilitationReinforcement of beam and pot floor with a cooperating cover layer
Quantity:22’000 m2 (15 mm)
Material:Micro-concrete fiber-reinforcedHPFRCC
The other Jobsite applications
48/83ICRI 2010 – Pittsburgh October 20-22
PROBLEMNECESSITY OF SEISMIC RETROFITTING OF THE STRUCTURE
The project foresees the realisation of RC shear walls destinated to resist the horizontal seismic actions
PROBLEM: TRASFER OF THE STRESSES OF THE FLOOR TO THE SHEAR WALLS; THE EXISTING FLOOR, WITH A STRUCTURALLY COOPERATING TOP DECK OF 2 cm, WAS NOT ABLE TO FULLFILL THIS FUNCTION
The other Jobsite applications
49/83ICRI 2010 – Pittsburgh October 20-22
SOLUTION
TO OBTAIN THE DIAPHRAGM EFFECT HAS BEEN INSTALLED ON THE TOPPING OF THE FLOOR A STRUCTURAL COOPERATIVE DECK WITH LOW THIKCNESS (15 mm) IN FIBRE-REINFORCED CONCRETE WITH VERY HIGH MECHANICAL PERFORMANCE, FORMULATED AD-HOC BASED ON THE STRUCTURAL REQUIREMENTS
The other Jobsite applications
50/83ICRI 2010 – Pittsburgh October 20-22
APPLICATION 1. VERIFICATION OF THE ADHESION TO SUBSTRATE
APPLICATION OF SAMPLE IN JOBSITE TO VERIFY THE ADHESION OF THE PRODUCT TO THE SUBSTRATE IN
THAT SITUATION:
• CONNECTORS WITH STUBS IN REFOR-tec® GF5/ST HS, OBTAINED THROUGH SIMPLE DRILLING
• METAL CONNECTORS (DRILLING + FISCHER)
• NO CONNECTORS- ONLY SANDBLASTING AND WATERJETTING
• NO CONNECTORS – ONLY WATERGETTING
The other Jobsite applications
51/83ICRI 2010 – Pittsburgh October 20-22
THE CURING PERIOD COMPLETED, MEASUREMENTS DEMONSTRATE THE ADHESION TO THE SUBSTRATE :
OPTIMAL ADHESION OF THE REINFORCING COVERLAYER REFOR-tec® GF5/ST HS EVEN WITHOUT CONNECTOR SYSTEM,
ONLY AFTER ADEQUATE SURFACE PREPARATION
The other Jobsite applications
52/83ICRI 2010 – Pittsburgh October 20-22
The other Jobsite applications
APPLICATION OF THE MATERIAL
53/83ICRI 2010 – Pittsburgh October 20-22
The other Jobsite applications
LIGHT TAMPERING
IMMEDIATE APPLICATION OF CURING COMPOUND UR 20
54/83ICRI 2010 – Pittsburgh October 20-22
The other Jobsite applications
DETAIL OF THE APPLICATION – RETAKING OF THE FLOORS
55/83ICRI 2010 – Pittsburgh October 20-22
TESTING-CONTROLLING THE ADHESION TO THE SUBSTRATE
The other Jobsite applications
56/83ICRI 2010 – Pittsburgh October 20-22
RESULTTHE APPLICATION OF SEVERAL THOUSEND SQUARE METERS
WITHOUT CUTTING JOINTS AND WITHOUT ANY CRACKING.
PERFECT ADHESION OF THE MATERIAL TO THE SUBSTRATE
The other Jobsite applications
57/83ICRI 2010 – Pittsburgh October 20-22
ADVANTAGES IN RESPECT WITH A TRADITIONAL CONCRETE COOPERATIVE DECK
1. Low application thickness (15-20 mm )
2. Adhesion the substrate without necessity for connectors or resins
3. No reinforcement nets
4. Very high ductility and resistance to cyclic load
5. Increase of the bearing capacity in terms of bending moment and stiffness and a reduction of the deflection of the floor
6. Speed of application thanks to self-levelling material properties
Limited increase of load
The other Jobsite applications
58/83ICRI 2010 – Pittsburgh October 20-22
Repair after fire
59/83ICRI 2010 – Pittsburgh October 20-22
Beams residual properties
4 Ø 16mm
300mm
500m
m
Steel
Felicetti & Meda (2005)
Concrete
Eurocode 2
60/83ICRI 2010 – Pittsburgh October 20-22
Thermal analysis
ISO 834
61/83ICRI 2010 – Pittsburgh October 20-22
Analytical model
Coccia & Rinaldi 2006
steel concrete
M
N h Ast
Asc
b
62/83ICRI 2010 – Pittsburgh October 20-22
0 60 120 180
Fire duration [m in]0
100
200
300 M om ent [kN m ]
Beams residual properties
63/83ICRI 2010 – Pittsburgh October 20-22
Beams repair
0 60 120 180
F ire duration [m in]0
100
200
300 M om ent [kN m ]
HPFRC
64/83ICRI 2010 – Pittsburgh October 20-22
0 250 500 750 1000
Temperature [C]0
0.25
0.5
0.75
1fct
T/fct20
HPFRCC
0 250 500 750 1000 1250
Tem perature [°C ]0
1
2
3
4Therm al conductiv ity [W m /K ]
HPFRCEC2
Mindeguia et al. (2007)
HPFRC
950°C
De Chefdebien et al. (2007)
HPFRC thermal properties
65/83ICRI 2010 – Pittsburgh October 20-22
Fire resistance of the repaired beam
0 60 120 180
Fire duration [m in]0
100
200
300
400 M om ent [kN m ]
66/83ICRI 2010 – Pittsburgh October 20-22
0 60 120 180
F ire duration [m in]0
100
200
300
400 M om ent [kN m ] In itia l dam age60'
90 '
120 '
Fire resistance of the repaired beam
67/83ICRI 2010 – Pittsburgh October 20-22
Column residual properties
68/83ICRI 2010 – Pittsburgh October 20-22
Column repair
69/83ICRI 2010 – Pittsburgh October 20-22
Initial damage 90′ - new fire 90′
70/83ICRI 2010 – Pittsburgh October 20-22
Initial damage 180′ - new fire 180′
71/83ICRI 2010 – Pittsburgh October 20-22
Seismic retrofitting ofshear walls
72/83ICRI 2010 – Pittsburgh October 20-22
Reference model: stair block element of an
existing three storey building
Experimental model:
1:3 scaled R/C wall
Experimental test
73/83ICRI 2010 – Pittsburgh October 20-22
t =15mm
Proportioned to resist
vertical loads only
Proportioned to resist seismic loads
aggregate dmax=15mm
F5/70mm longit. rebars
F4/100mm stirrups
Experimental test
74/83ICRI 2010 – Pittsburgh October 20-22
0 0.04 0.08 0.12 0.16 0.2
Stra in0
500
1000
1500 Stress [M Pa]
F
A L
L
L / LF / A
High strength,
waved steel mesh made
of bent wires
Tensile test on steel mesh single wire
High performance steel mesh
75/83ICRI 2010 – Pittsburgh October 20-22
0 10 20 30
D isp lacem ent [m m ]0
5
10
15
20 Load [kN ]
W ithout concrete
10m m th ick concrete
20m m th ick concrete
Specimen A
Specimen B
9010
90
20
high performancefiber concrete
high strength steel meshwith bent wires
1 1 Section 1-1
90
250
bare high
strength
steel mesh
High performance jacket
76/83ICRI 2010 – Pittsburgh October 20-22
I phase:R/C wall sandblast
Wall sandblast
77/83ICRI 2010 – Pittsburgh October 20-22
I phase:R/C wall sandblast
II phase:Positioning ofthe steel mesh
Application of the steel mesh
78/83ICRI 2010 – Pittsburgh October 20-22
I phase:R/C wall sandblast
II phase:Positioning of
the steel mesh
III phase:15 mm HPC
jacket casting
Jacket casting
79/83ICRI 2010 – Pittsburgh October 20-22
50 100 150
Top d isplacem ent [m m ]
25
50
75
100 Load [kN ]
-150 -100 -50
-100
-75
-50
-25
20
50
-20
-50
F
-100
-80
-60
-40
-20
0
20
40
60
80
100
-80 -30 20 70 120
Bas
e S
hear
for
ce [
kN]
top displacement [mm]
with jacket - experimental
envelope curve
drift 3.6%u/y = 9
y= 12mm; u= 109mm)
Results
80/83ICRI 2010 – Pittsburgh October 20-22
Deformed shear wall at collapse Deformed shear wall at collapse
drift = 3.5%
1.5b
12/16
Results
81/83ICRI 2010 – Pittsburgh October 20-22
Fiber element
S1
S2
S4
S5
S3
II
I
III
base section
fiberelement
FE model
1
2
3
fibersection
Existing R/C wall
Strengthened R/C wall
(Spacone et al. 1996)
FE analysis
82/83ICRI 2010 – Pittsburgh October 20-22
FE analysis: results
-100
-80
-60
-40
-20
0
20
40
60
80
100
-80 -30 20 70 120
Bas
e S
hear
for
ce [
kN]
top displacement [mm]
with jacket - experimental
with jacket - numeric
unreinforced - numeric
83/83ICRI 2010 – Pittsburgh October 20-22
Conclusions
- The proposed technique allow a significant increase of the bearing capacity in terms of bending moment, axial force and stifness of pillars and beams
- A simple sandblasting has ensured the perfect bond between the base concrete material and the strengthening UHPFRCC layer;
- The strengthening has provided a remarkable increase of stiffness of beams and floors; as a consequence, the midspan displacement at serviceability limit state has been reduced of about 12 times; This behaviour is comparable to the application of a prestressing load;
- The small thickness of the jacket does not change significantly the elements geometry
- Increase of thermal and static resistance of structural elements after the fire
-The jacket enhance the durability of the structure