Loading...

Assessment of Atmospheric Corrosion Effects on Seismic Performance and Risk of Steel Structures Using the Endurance Time Method

Morshedi, Mohsen | 2025

26 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58590 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Esmaeil Pourestekanchi, Homayoon
  7. Abstract:
  8. This research investigates the effect of atmospheric corrosion on the seismic performance and seismic risk of steel structures. Corrosion, as the most significant deterioration mechanism in steel structures, reduces their stiffness and strength; however, its effect is often neglected in most seismic risk assessments. In this research, six corrosivity levels (C1–CX) were defined according to the ISO standard, and their effect on the seismic performance of 10 special steel moment frames with different geometric characteristics was evaluated. In this regard, after the modeling and design of the structures based on design codes, time-dependent models were developed by combining nonlinear modeling and corrosion modeling. Next, period analysis, pushover analysis and the Endurance Time (ET) analysis-a computationally efficient incremental dynamic analysis-were performed to assess the effect of corrosion. Results from the period and pushover analyses demonstrated that very low (C1) and low (C2) corrosion levels cause less than a 1% reduction in structural stiffness and strength over a 50-year service life, indicating that their effects can be neglected in design. Furthermore, by performing Endurance Time analyses for medium (C3) to extreme (CX) corrosivity levels, time-dependent seismic fragility curves were developed based on the peak drift ratio and peak floor acceleration responses. By combining the seismic hazard curve with the fragility curves, the effects of corrosion on annual and life-cycle seismic vulnerability were evaluated. The results demonstrated that corrosion has a significant effect on drift response, while its effect on acceleration response is negligible and can be considered independent of corrosion. Any level of corrosion increases fragility with respect to drift response across all intensity and damage levels, and the seismic fragility consistently increases with higher corrosion levels. Moreover, the effect of corrosion is considerably greater at extensive and complete damage states compared to slight and moderate levels. In other words, the adverse effect of corrosion on seismic fragility and seismic vulnerability intensifies with increasing seismic intensity. Sensitivity analyses with respect to structural geometric characteristics demonstrated that the effect of corrosion on seismic performance and seismic vulnerability is not strongly dependent on column height or bay length; however, it decreases with increasing structure height. In other words, corrosion has a more effect on low-rise structures than on mid-rise or high-rise ones
  9. Keywords:
  10. Atmospheric Corrosion ; Seismic Performance ; Seismic Vulnerability ; Seismic Risk Index ; Endurance Time Method ; Fragility Curve ; Time-Dependent Fragility Curves

 Digital Object List

 Bookmark

No TOC