Comparison of output-only methods for modal identification of a twelve-span viaduct

Xinghua Chen, Piotr Omenzetter, Sherif Beskhyroun

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)peer-review

2 Citations (Scopus)
17 Downloads (Pure)


The recently constructed Newmarket Viaduct in Auckland is a critical link in the New Zealand state highway network. Newmarket Viaduct is a 12-span, pre-cast, post-tensioned structure built using the balanced cantilever method. As a newly constructed bridge, it is essential to measure the actual dynamic characteristics of the bridge to assists in understanding of its dynamic behavior under traffic, seismic and other live loads. Thus, one-off, two day-long modal testing campaign using 56 wireless sensors in multiple setups was conducted under operational conditions to collect vibration data. As part of the ensuing dynamic response studies, this paper presents a preliminary study on data analysis and evaluation of four different system identification procedures for modal parameter identification of Newmarket Viaduct based on ambient vibration measurements. The four methods are the peak-picking and the enhanced frequency domain decomposition in the frequency domain, and the eigenrealization algorithm combined with the natural excitation technique and the stochastic subspace identification method in the time domain. After the comparison based on the estimated natural frequencies and mode shapes, the study discusses the advantages and disadvantages of each of the methods, which will be helpful for the future studies and applications of output-only modal analysis.
Original languageEnglish
Title of host publicationProceedings of the 5th International Operational Modal Analysis Conference
Number of pages8
Publication statusPublished - 13 May 2013
Event5th International Operational Modal Analysis Conference - Guimarães, Portugal
Duration: 13 May 201315 May 2013


Conference5th International Operational Modal Analysis Conference
Abbreviated titleIOMAC'13

Bibliographical note

The authors would like to express their gratitude to their supporters. Research work at the University of Auckland was supported by the Earthquake Commission Research Foundation grant UNI/578. Piotr Omenzetter’s work within The LRF Centre for Safety and Reliability Engineering at the University of Aberdeen is supported by The Lloyd's Register Foundation (The LRF). The LRF supports the advancement of engineering-related education, and funds research and development that enhances safety of life at sea, on land and in the air. NGA Newmarket facilitated the field testing and New Zealand Transport Agency allowed the use of Newmarket Viaduct for research. Gewei Chen and Shahab Ramhormozian, PhD students at the University of Auckland, assisted with the ambient vibration tests.


  • bridge
  • dynamic characteristic
  • ambient vibration test
  • modal identification
  • wireless sensors


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