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 and October 22, 2014

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. 2 Motivation 2 Paint flaking of partially hidden EBF link & global view of EBF braces obstructed by various utility runs. [Photos by M. Bruneau and C Clifton] Fractured EBF in Pacific Tower, from Bruneau et al. 2012

EBF Building Damage in the 2011 M6.3 Christchurch, New Zealand Earthquake  Club Tower building, completed in  estimates of the peak inelastic demand in the active link were made through visible assessment of the active link yielded web metal. 3 Paint flaking of partially hidden EBF link & global view of EBF braces obstructed by various utility runs. [Photos by M. Bruneau and C Clifton]

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 5

Resilience Metrics (Ayyub 2013) R e > 0 6

Measuring Performance (Ayyub 2013) 7

Resilience Metrics (Ayyub 2013) 8 Re < 1Re < 1 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.

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 t r1 t r2 Q f1 Q f0 Q f2

 Structural health monitoring system should generate an alarm signal whenever the strain exceeds the pre-specified limit state (e.g., yielding, fracture or buckling).

Hybrid simulation test setup for system validation of WSCA on truss structure

Component Validation Test Brittle Bar Size H6W4H9W2 Test #10.65%1.10% Test #20.61%1.02% Ave. of Test values 0.63%1.06% Design value0.55%1.18%

Alternative test plan Data acquisition system BIM user interface RFID reader stub column specimen with BT strain sensors

Experimental Validation Test

 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. Concluding Remarks 16

Thank you