structural health monitoring in virginia › 2015_sebpp › pdf › 10...structural health...
TRANSCRIPT
-
Structural Health Monitoring in Virginia
Bernie Kassner, Ph.D., P.E. Southeast Bridge Preservation Partnership Meeting April 14, 2015
-
• Delta Frame Bridge +Reconstruction Monitoring +Fatigue Monitoring
• Varina-Enon Bridge +Segmental Joint
Monitoring
• Ancillary Structures +Vibration Monitoring
Projects
-
845’
-
4/20/2015
155’
-
• Background +Original design in 1969
+Constructed in 1976
+Fatigue problems discovered in late '80’s
+Retrofits done in 1992
+Additional retrofits recommended in 2009
+2013 TIGER grant awarded
Delta Frame Bridge Reconstruction
-
• Motivation for Monitoring +Concrete deck replacement
+Complex structure
+Modeling showed areas of large stresses / movements
+Monitoring needed during construction
Delta Frame Bridge Reconstruction
by p
erm
issi
on o
f Whi
tman
, Req
uard
t, an
d A
ssoc
iate
s, L
LP
-
• Instrumentation: SENSR CX-1 +Acceleration in 3
directions +Rotations in 2
directions
+Temperature
+Range of 750 ft
+Data collected remotely
+System is power-hungry
Delta Frame Bridge Reconstruction
-
• Monitoring +Continuous throughout each phase +Alert can be sent if threshold limits are exceeded +Video observation of construction activity +Possible continued monitoring after completion
Delta Frame Bridge Reconstruction
-0.20-0.15-0.10-0.050.000.050.100.150.200.250.30
10/14 11/3 11/23 12/13 1/2 1/22 2/11 3/3 3/23
Rot
atio
n (d
eg)
Date
R.e2.r (Exterior Girder at Pier 2, Right of Knuckle) Tilt X Tilt Y
-
• Thermoelastic Stress Analysis (TSA) +Detection of fatigue cracks
+Relies on principle of thermoelasticity:
+Uses low-cost IR camera
+Some signal processing is required
∆TtE = ̶ KT∆(σ1 + σ2)
Delta Frame Bridge Fatigue
-
Raw Data Thermoelastic Response
Delta Frame Bridge Fatigue
-
Delta Frame Bridge Fatigue
Crack
Gross Stress: 14 ksi Gross Stress: 10 ksi Gross Stress: 5 ksi
-
Delta Frame Bridge Fatigue
-
Varina-Enon Bridge Joint Monitoring
0.3L Span 6
150’
-
• Visual Inspection + June 2012 + Observed 1/16-in. joint
opening under normal traffic + 103°F
• Load Test + 294 kip live load + Recorded 1/64-in. opening + 85°F
Varina-Enon Bridge Joint Monitoring
-
Varina-Enon Bridge Joint Monitoring • Long-term Instrumentation
+2 LVDTs monitoring joint opening
+1 Strain transducer next to joint
+24 Thermocouples measuring thermal gradient
+1 Trigger strain transducer
-
Varina-Enon Bridge Joint Monitoring • Long-term Instrumentation
+2 LVDTs monitoring joint opening
+1 Strain transducer next to joint
+24 Thermocouples measuring thermal gradient
+1 Trigger strain transducer
-
Varina-Enon Bridge Joint Monitoring • Long-term Instrumentation
+2 LVDTs monitoring joint opening
+1 Strain transducer next to joint
+24 Thermocouples measuring thermal gradient
+1 Trigger strain transducer
-
Varina-Enon Bridge Joint Monitoring
September 2012 – September 2013 4673 Strain Events
290 Joint Openings > 0.003”
Maximum Recorded Joint Opening ~1/32”
• Long-term Results
-
Varina-Enon Bridge Joint Monitoring
July • Long-term Results
December
51 joint openings > 0.003” 0 joint openings > 0.003” 537 strain events 277 strain events
Rel
ativ
e Jo
int D
ispl
acem
ent (
in.)
Ther
mal
Gra
dien
t (°C
)
Strain at 0.4L (µε)
-
• 32,300 structures in VA + Luminaires + Signs + Traffic signals + High mast lights + Camera poles
Ancillary Structures Monitoring
-
• 32,300 structures in VA + Luminaires + Signs + Traffic signals + High mast lights + Camera poles
• Short-term monitoring
Ancillary Structures Monitoring
http://www.sensr.com
-
• Delta Frame Bridge +Reconstruction Monitoring +Fatigue Monitoring
• Varina-Enon Bridge +Segmental Joint
Monitoring
• Ancillary Structures +Vibration Monitoring
Summary
-
Special Thanks • Thermoelastic Stress Analysis
Dr. Steve Chase University of Virginia
• Varina-Enon Bridge Dr. Carin Roberts-Wollmann Virginia Tech Dr. Marc Maguire Utah State University
Thank You!
Questions?
Structural Health Monitoring�in Virginia ProjectsSlide Number 3Slide Number 4Delta Frame Bridge ReconstructionDelta Frame Bridge ReconstructionDelta Frame Bridge ReconstructionDelta Frame Bridge ReconstructionDelta Frame Bridge FatigueDelta Frame Bridge FatigueDelta Frame Bridge FatigueDelta Frame Bridge FatigueSlide Number 14Varina-Enon Bridge Joint MonitoringVarina-Enon Bridge Joint MonitoringVarina-Enon Bridge Joint MonitoringVarina-Enon Bridge Joint MonitoringVarina-Enon Bridge Joint MonitoringVarina-Enon Bridge Joint MonitoringAncillary Structures MonitoringAncillary Structures MonitoringSummaryThank You!