Overview

The research efforts in seismic structural health monitoring have focused on developing expertise on system identification approaches as well as developing tools for post-processing of data, including a GUI interface for MATLAB to enable near real-time processing in the field during experimentation. USGS, Caltrans, and the NSF CMS sensor program have been targeted to obtain funding support. As well, NSF-funded NEES@UCLA has been used to provide supplemental support for CENS Factor-related activities.   

Approach

Our approach has been to develop three overlapping thrust areas on: (1) Numerical/analytical modeling, (2) field testing, (3) enhancing equipment, and (4) securing funding. Each of these areas is discussed briefly:

 

1. Numerical/analytical work has focused on developing tools and approaches for system identification, model updating, and damage detection. A majority of this work has been accomplished using data from the UCLA Factor building, the Four Seasons building forced-vibration tests conducted in 2004, and laboratory tests of a small-scale structure. Considerable effort has been expended on the system identification and model updating, whereas work on damage detection is planned. A number of conference papers and journal papers have been prepared.
2. Conduct field testing of structural systems is seen as essential. Our goals include a system level test that could be used as a test-bed to address issues related to sensor timestamps, local processing including performance-based real-time monitoring, and damage detection. The performance-based design aspect of the work is based on implanting the work being conducted by the NSF Pacific Earthquake Engineering Research (PEER) Center.
3. Improve our field-testing capabilities by incorporating/developing new equipment into our NEES@UCLA equipment portfolio. The equipment envisioned includes a relatively small-scale eccentric mass shaker that could be set up and run with relatively effort compared with current shakers and a relatively large force capacity linear shaker system (100 to 200 kips maximum capacity). The small-scale shaker will be purchased as an equipment enhancement on NEES@UCLA, whereas a pre-proposal for the linear shaker was submitted to HS-SEAS at UCLA as consideration as an MRI (and not selected).  
4. To achieve this goal, we have submitted proposals over the last 6 months to USGS and Caltrans to conduct forced-vibration testing. Testing in the USGS proposal consisted for forced-vibration testing of structures that will be instrumented by ANSS, whereas the Caltrans pre-proposal included forced-vibration testing of highway overpasses. In additional to the Work has initiated on preparing an NSF CMS proposal based on a visit to NSF CMS Program Director Shih-Chi Liu. For this proposal, we envision a multi-hazard scope, including earthquakes, blast, and homeland security monitoring combining the talents of Civil Engineering researchers JS Chen, E. Taciroglu, J. Wallace, and R. Nigbor, with CENS researchers and CENS/NEES staff assistance.
   
   

Systems/Experiments

Substantial equipment exists in the NEES@UCLA portfolio to conduct comprehensive field experiments. Enhancements, to address shortcomings that have been identified in prior testing, were mentioned in the previous section. Although we are well-equipped for field testing, progress has been slowed by our need to secure external funding to support actual field tests.

 

Robert Nigbor, NEES@UCLA Project Manager, has continued to work with CENS researchers to enhance the UCLA Factor Building sensor array and to utilize its data.   He has assisted with the installation of a surface reference sensor and repair of the borehole reference sensor.  He has participated in discussion groups regarding Factor measurements and data.  He continues to work with Mark Hansen of UCLA Statistics and two graduate students to study data from active experiments using elevator-induced vibrations. He is also a member of the ANSS Technical Implementation Committee and the ANSS Structural Response Monitoring Committee, both of which provide high-level review of ANSS structural monitoring, including the Factor Building.

Accomplishments

Specific accomplishments over the last 12 months include:

Submitted Proposals:

1. Development of Instrumentation and Structure Metadata for ANSS-Monitored Structures, United States Geological Survey, 4/1/06 – 3/31/08, proposed budget $99,450. (declined, but resubmittal requested)
2. Full Scale Large Deflection Dynamic Testing of Bridge Systems to Support the Verification of Seismic Analysis and Design Tools, California Department of Transportation, pre-proposal, October 2005. (declined)

 

Journal Papers submitted:

1. Skolnik, D.; Ying, L.; Yu, E.; and Wallace, J. W., “Identification, Model Updating, and Response Prediction of an Instrumented 15-Story Steel Frame Building,” Earthquake Spectra, (in-press, to appear in August 2006).
2. Yu, Eunjong; Skolnik, Derek; Whang Daniel; Wallace, John W., “Forced Vibration Testing of a Four Story RC Building utilizing the nees@UCLA Mobile Field Laboratory,” Earthquake Spectra, submitted for review, January 2006.
3. Eunjong Yu, Ertugrul Taciroglu, and John W. Wallace, “Parameter Identification of Framed Structures Using An Improved Finite Element Model Updating Method—Part I: Formulation & Validation,” Earthquake Engineering and Structural Dynamics, submitted for review, January 2006.
4. Eunjong Yu, Ertugrul Taciroglu, and John W. Wallace, “Parameter Identification of Framed Structures Using an Improved Finite Element Model Updating Method—Part II: Application to Experimental Data,” Earthquake Engineering and Structural Dynamics, submitted for review, January 2006.

 

Conference papers:

1. Skolnik, D.; Ying, L.; and Wallace, J. W., “Identification and Model Updating of the UCLA Louis Factor Building,” The 2nd International Conference on Structural Health Monitoring of Intelligent Infrastructure: SHMII-2, November 16-18, 2005
   Shenzhen, P. R. of China.

 

Reports:

1. Yu, Eunjong; Skolnik, Derek; Whang Daniel; Wallace, John W., Forced Vibration Testing of a Four Story RC Building utilizing the nees@UCLA Mobile Field Laboratory,” UCLA S/EERL Report No. 2006/xx, University of California, Los Angeles, Department of Civil & Environmental Engineering, March 2006. (in preparation).
2. Skolnik, D.; Ying, L.; Yu, E.; and Wallace, J. W., “Identification, Model Updating, and Response Prediction of an Instrumented 15-Story Steel Frame Building,” UCLA S/EERL Report No. 2006/xx, University of California, Los Angeles, Department of Civil & Environmental Engineering, March 2006. (in preparation).

Future Directions

Future directions for work in the seismic structural health monitoring area include three major goals:

1. secure research funding to support field testing,
2. enhance interactions with CENS researchers and staff to address interdisciplinary research tasks related to timing and processing,
3. conduct field testing test-bed experiment to enable the research activities and interactions.

 

People

• John W. Wallace, Professor, UCLA Department of Civil & Environmental Engineering.
• Ertugrul Taciroglu, Assistant Professor, UCLA Department of Civil & Environmental Engineering.
• Robert Nigbor, Researcher, NEES@UCLA Project Manager, UCLA Department of Civil & Environmental Engineering.
• Eunjong Yu, Post-Doctoral Researcher, UCLA Department of Civil & Environmental Engineering.

• Derek Skolnik, Graduate Student Researcher, UCLA Department of Civil & Environmental Engineering.
• Steve W. Kang, Programmer Analyst, NEES@UCLA System Administrator, UCLA Department of Civil & Environmental Engineering.