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Determining the effective system damping of highway bridges.

File Language:
English


Details

  • Creators:
    Feng, Maria Q. ; Lee, Sung Chil
  • Corporate Creators:
    University of California, Irvine. Department of Civil and Environmental Engineering
  • Subject/TRT Terms:
  • Publication/ Report Number:
    CA-UCI-2009-001
  • Resource Type:
    Tech Report
  • Geographical Coverage:
    California
  • Corporate Publisher:
    California. Department of Transportation
  • Abstract:
    This project investigates four methods for modeling modal damping ratios of short-span and isolated ; concrete bridges subjected to strong ground motion, which can be used for bridge seismic analysis ; and design based on the response spectrum method. The seismic demand computation of highway ; bridges relies mainly on the design spectrum method, which requires effective modal damping. ; However, high damping components, such as embankments of short-span bridges under strong ; ground motion and isolation bearings make bridges non-proportionally damped systems for which ; modal damping cannot be calculated using the conventional modal analysis. In this project four ; methods are investigated for estimating the effective system modal damping, including complex ; modal analysis (CMA), neglecting off-diagonal elements in damping matrix method (NODE), ; composite damping rule (CDR), and optimization in time domain and frequency domain (OPT) and ; applied to a short-span bridge and an isolated bridge. ; The results show that among the four damping estimating methods, the NODE method is the most ; efficient and the conventional assumption of 5% modal damping ratio is too conservative for short-span bridges when energy dissipation is significant at the bridge boundaries. From the analysis of ; isolated bridge case, the effective system damping is very close to the damping ratio of isolation ; bearing.
  • Format:
    PDF
  • Funding:
    RTA59A0495
  • Download URL:
    https://rosap.ntl.bts.gov/view/dot/27548/dot_27548_DS1.pdf
  • File Type:
    Filetype[PDF - 1.94 MB]
  • Collection(s):
    US Transportation Collection
  • Main Document Checksum:
    urn:sha256:1b3b3be02adcfe6f8ea29d7555f7a15ca8fc064d60cce7efd3d39b0409ce3d32
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