Transcript Monitoring the Health of Structures for Quantifying and Achieving
October 22, 2014
Monitoring the Health of Structures for Quantifying and Achieving Resilience for Natural Hazards
Bilal M. Ayyub and
Yunfeng Zhang
Department of Civil & Environmental Engineering University of Maryland, College Park [email protected]
Motivation
• After natural hazardous events, engineers are usually faced with many competing priorities in making safety and occupancy decisions about large inventories of building and bridge assets , which could be more effectively managed through automated inspection and computerized condition assessment . Fractured EBF in Pacific Tower, from Bruneau et al. 2012 2
EBF Building Damage in the 2011 M6.3 Christchurch, New Zealand Earthquake
Club Tower building, completed in 2009. estimates of the peak inelastic demand in the active link were made through visible assessment of the active link yielded web metal.
Paint flaking of partially hidden EBF link & global view of M. Bruneau and C Clifton] 3
CBF Building Damage in the 1994 M6.7 Northridge Earthquake (California)
• • • The building remained plumb following the earthquake.
The initial assessment of the structure by the owner's representative was that the structure had not sustained much damage (only one window had been broken). Only after the dry wall was removed, the extent of damage was revealed. 4 Photos from Sabelli 2013 and Trembaly 1995
Clearly, ability of rapid structural condition assessment especially for many hidden locations after major hazardous events reduces the time to recovery and increases the resilience in disaster recovery Rapid condition assessment 100% 50% 0 Q 0h1 Q 0h2 t f t f + T r1 Conventional inspection approach t f + T r2 5 Time
Resilience Metrics (Ayyub 2013)
Performance “as new” A Poisson process with rate l leading to an incident occurrence Target Failure event definitions: f1. Brittle f2. Ductile f3. Graceful Recovery event definitions: r1. E. better than new r2. E. as good as new r3. E. better than old r4. E. as good as old r5. As good as old r6. Worse than old E. = Expeditiously f1 f2 f3 r1 r2 r3 r4 r5 r6 Robustness, i.e., residual performance (
Q r
) Estimated performance with aging effects Performance after recovery Disruption duration T
d
Recovery duration T
r
Failure duration T
f T r
= Time to recovery
T f
= Time to failure
T i
= Time to incident 0 0
t i t f t r
Resilience ( Recovery costs
R e
)
T i T i
F
T f
Indirect impacts including loss of
R
T r
T f
T r
6 0
R e
Direct failure
>
0
Not to scale
Time Impacts valuated Failure (
F
)
t i t
f fdt t t i
f Qdt
Recovery (
R
)
t r f
t rdt t r f
t Qdt
Measuring Performance (Ayyub 2013)
Systems
Buildings Other structures: Highway bridges
Performance
Space availability Throughput traffic Facilities: Water treatment plants Infrastructure: Water delivery Water production capacity Water available for consumption Network: Electric power distribution Power delivered Communities Economic output Quality of life (consumption)
Units
Area per day Count per day Volume per day Volume Power per day Dollars Dollars 7
Resilience Metrics (Ayyub 2013)
Resilience (
R e
)
T i T i
F
T f
T f
R
T r
T r R e <
1 Failure (
F
)
t t i
f fdt t t i
f Qdt
Recovery (
R
)
t r f
t rdt t r f
t Qdt
The failure-profile value (F) can be considered as a measure of robustness and redundancy; whereas the recovery-profile value (R) can be considered as a measure of resourcefulness and rapidity. 8
Definition for resilience components
Measuring resilience based on its components (MCEER): Robustness as the ability of the system and system elements to withstand external shocks without significant loss of performance Redundancy as the extent to which the system and other elements satisfy and sustain functions in the event of disturbance Resourcefulness as the ability to diagnose and prioritize problems and to initiate solutions by identifying and monitoring all resources, including economic, technical, and social information Rapidity as the ability to recover and contain losses and avoid future disruptions 9
Resilience concept of functionality versus recovery time
A Poisson process with rate l leading to an incident occurrence Performance “as new” Target
Q f1 Q f0 Q f2
Failure event definitions: f1. Brittle f2. Ductile f3. Graceful Recovery event definitions: r1. E. better than new r2. E. as good as new r3. E. better than old r4. E. as good as old r5. As good as old r6. Worse than old E. = Expeditiously f1 f2 f3 r1 r2 r3 r4 r5 r6 Robustness, i.e., residual performance (
Q r
) Estimated performance with aging effects Performance after recovery Disruption duration T
d
Recovery duration T
r
Failure duration T
f
0 0
T r
= Time to recovery
T f
= Time to failure
T i
= Time to incident
t i t f
Recovery costs
t r t r1 t r2
Indirect impacts including loss of performance Direct failure impacts
Not to scale
Time 0 Impacts valuated
Structural health monitoring system should generate an alarm signal whenever the strain exceeds the pre-specified limit state (e.g., yielding, fracture or buckling).
Strain gage 1 Strain gage 2 Strain gage 1 30 in (0.76 m) RFID reader Hybrid simulation test setup for system validation of WSCA on truss structure
Component Validation Test
-12000 -10000 Gage 1 Gage 2 -8000 -6000 H6W4-FEM -4000 -2000 0 0 H9W2-FEM H6W4 H9W2 50 100 150 200 250 Time (sec.) 300
Test #1 Test #2 Ave. of Test
350
values
400
Design value Brittle Bar Size H6W4
0.65% 0.61%
H9W2
1.10% 1.02% 0.63% 450 0.55% 1.06% 500 1.18%
Alternative test plan
Data acquisition system RFID reader BIM user interface stub column specimen with BT strain sensors
Experimental Validation Test
350 300 250 H6W4 200 150 H9W2 100 50 0 0 0.005
0.01
0.015
0.02
Axial strain 0.025
0.03
0.035
Concluding Remarks
Resilience metrics is defined For such seismically resilient structures with fuse members, automated wireless scanning of fuse zone for possible damages suffered during earthquakes or strong winds could be performed in a very efficient way and this practice would greatly accelerate condition assessment and thus enhance resilience through shorter and more accurate inspection. 16