New paper : Noncontact Operational Modal Analysis of Structural Members by LDV February 2, 2009
Posted by dionsiringo in Vibration, mechanical vibration.add a comment
A system that uses ambient vibration and two laser Doppler vibrometer (LDV) is developed for noncontact operational modal analysis of structural members. The system employs natural excitation technique (NExT) to generate the cross-correlation functions from laser signals, and the eigensystem realization algorithm (ERA) to identify modal parameters of structural members. To facilitate simultaneous modal identification, time-synchronization technique and construction of cross-correlation functions from ambient response of laser signals are proposed. Performance of the proposed system is verified experimentally by evaluating the consistency and accuracy of identification results in different measurement conditions. The work presented here is an extension of the previous study, where a modal-based damage detection method using LDV was formulated.
In the present study, application of LDV for structural parameters identification of a combined dynamical system is proposed. A model that represents the connection properties in terms of additional stiffness and damping is developed, and its importance for structural damage detection is discussed. The study shows that the presence of simulated damage in a steel connection can be detected by tracking the modal phase difference and by quantifying the additional stiffness and damping.
IABSE Chicago and UIUC Trip October 1, 2008
Posted by dionsiringo in Structural Monitoring, Vibration, proceeding, visit.add a comment
Last week I attended the 17th IABSE Congress in Chicago. My colleague Dr. Nagayama presented a paper with me as the a co writer. The conference was great. Most of participants are engineers from big firms and famous consultants companies. Few are from academics. This sort of mixed audience is good for a change. It’s always a good thing to get feedbacks from engineers.
This is the paper presented at IABSE congress. It’s a modification of our previous works on bridge monitoring using ambient and seismic response. There are lots of paper that are very interesting to me, especially about long span bridge and tall building. I’ll post them next time.
Couple of days before IABSE Conference we visited the UIUC at Urbana-Champaign, where I visited Prof. Spencer’s Lab and participated on measurement of an old truss bridge using IMOTE2. The measurement was lead by Nagayama, couple of students from UIUC assisted us. It was a great experience. The collaboration was featured in UIUC research buletin.
