Transcript No Slide Title

Instrumentation and Modeling of Concrete Bridge Decks
Sponsored by:
Matthew D'Ambrosia, Chang Joon Lee, David Lange, Zachary Grasley
MATERIALS
FINITE ELEMENT MODELING
OBJECTIVES
Measure strain and temperature of six newly
Bridge
Building the model consisted of three stages
Total Length (ft) # of Spans Span Length
Beam Type
Beam Spacing
I-72/Duncan Rd.
222
4
41/68
33" steel WF beam
6'-6"
I-70/Big Creek
272
4
67/68
42" concrete bulb tee
7'-9"
constructed concrete bridge decks
Assess overall deck behavior during daily
6:00
12:00
)
Shrinkage Strain (x10
0:00
18:00
Concrete girder
MPC
Pin support  dx dy dz fixed, θx θy θz free
Temperature(oC)
MPC  Different nodal point for temperature, Geometric accuracy
15
15
15.5
16
16.5
Time(day)
17
17.5
 Deck-girder interaction
 Structural system/boundary conditions
300
600
200
400
Field Data
Big Creek
3.15
2.65
2.20
2.67
2.60
515
140
545
oz/cwt
oz/cwt
oz/cwt
1863
1108
0.44
0.72
25
1820
1240
0.44
1.01
1.51
6.19
-100
-200
Majority of stress development over time is
Bottom Surface
200
0
Stress(psi)
Microsstrain (  )
Deformation Map (1000x) Big Creek Bridge, 56 Days
0
-200
-400
Analysis
Top Surface
-400
-500
-600
0
10
20
30
40
Age (day)
50
60
70
80
0
10
50
60
70
80
Field Data
Stress(psi)
200
0
-100
-200
Analysis
-300
due to drying shrinkage - Temperature changes
deform the whole bridge system, including the
girders and do not induce very much stress
Role of shrinkage on bridge deck stress
400
100
Microsstrain (  )
40
Age (day)
Bottom Surface
200
thermocouples
30
600
300
Mid-top
20
(a) DUNCAN – STEEL GIRDER, Location A
(a) DUNCAN, location A
0
BIG CREEK / 56 DAYS
Top Surface
-200
700
-400
600
-600
-500
0
10
20
30
40
Age (day)
50
60
70
0
10
20
30
80
40
Age (day)
50
60
70
80
(b) BIG CREEK – CONCRETE GIRDER, Location A
(b) BIG CREEK, Location A
Model strain validated with actual field strain measurements
Model stress predictions show higher stress in concrete beam bridge
transmits data through
analog cellular phone
modem connection
MAX. STRESS (PSI)
-400
Cellular antenna -
Duncan Rd
similar concrete materials showed that structural
restraint produces higher stress in the bridge
with concrete beams. Stresses were generated
in areas of higher restraint such as over the pier
and over the girders
-300
Strain gage and thermocouple positions
SG
Comparison of two bridge structures with
Deformation Map (1000x) Duncan Rd Bridge, 56 Days
#4 reinforcing bars
strain gages
400
successfully with field strain measurements
using field temperature measurements and
material model as input
100
1.0"
300
Structural finite element model was validated
 Skewed alignment
 Continuous supports
 275’ long, 4 spans, longest span 67 feet
 Concrete girders
 16 strain gages, 26 thermocouples, 6 RH sensors
3.8"
200
DISCUSSION AND
CONCLUSIONS
 High performance concrete bridge deck
Mid-bot
100
Cement (Type I)
Fly Ash
Silica Fume
Coarse Aggregate
Fine Aggregate
w/c ratio
AEA (Grace Daravair 1400)
Type A WR (Grace Daracem 65)
Type F HRWR (Grace Daracem 19)
18
(typical for other bridges)
6.5"
0
Bridge Name
Example:
I-70/Big Creek Bridge, Clark Co., IL
Mid-mid
-500
Roller support  dx dz free, dy fixed, θx θz free, θy fixed
A7
RESULTS
Typical Sensor Locations
-400
Concrete Mixture Proportions
Shell Element
INSTRUMENTATION
C
IDL41R1
-300
-700
Pier
25
Thermal Analysis
Datalogger
IDL44R1
Age
term cracking. Evaluate material and structural
interaction and implications for design
A
-200
-600
Node
30
A1
IBL44R1
-6
Shell Element
20
B
esh(t, to) - B3
-100
Determine stress development in concrete
Assess the potential for early age and long
Draft Recommendation B3 fit with laboratory
test data and incorporated into structural model
0
cycles and long term changes of temperature
and internal humidity
deck due to drying shrinkage and temperature
changes using field data and FEM
Shrinkage and creep modeled using RILEM
500
400
BOTTOM SURFACE
300
200
100
TOP SURFACE
0
-100
20
Solar panel - charges
40
60
80
100
% OF MEASURED SHRINKAGE PLUS CREEP
12 V lead-acid battery
Can low shrinkage concrete avoid cracking?
Datalogger – reads
sensors and stores data
until transmission
Data collection and transmission system
28
30
35
70
84 Days
21
28
42
56 Days
Shrinkage reduction of 15-40% would reduce most tensile
stresses below 400 psi and reduce cracking
Maximum stress development in Duncan Rd bridge, 200 psi threshold
(max. stress is less than 400 psi)
Maximum stress development in Big Creek bridge, 400 psi threshold