Load rating and FRP retrofitting of bridge abutment timber piles.

Details

• Alternative Title:
  Load rating and FRP retrofitting of bridge abutment timber piles : a report of the findings of ICT project R27-134, strengthening of bridge wood piling retrofits for moment resistance, phase II.
• Creators:
  Kim, Kun-Ho E ; Andrawes, Bassem
• Corporate Creators:
  Illinois Center for Transportation ; University of Illinois at Urbana-Champaign. Department of Civil and Environmental Engineering
• Corporate Contributors:
  Illinois. Department of Transportation. Bureau of Materials and Physical Research ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Bridge abutments
  • Deterioration
  • Fiber reinforced polymers
  • Load factor
  • Load tests
  • Nondestructive tests
  • Piles (Supports)
  • Retrofitting
  • State of the practice
  • Timber Timber piles
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• Publication/ Report Number:
  FHWA-ICT-16-011;ICT-16-012;UILU-ENG-2016-2012
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States;Illinois
• Edition:
  Phase II Final Report
• Corporate Publisher:
  University of Illinois at Urbana-Champaign
• Abstract:
  This report details Phase II of the study titled Strengthening of Bridge Wood Piling Retrofits for Moment Resistance. Phase I of the research (project ; R27-082) was focused on developing a load rating method for timber piles under eccentric load and examining FRP retrofitting of pier piles. ; However, Phase II focused first on numerically assessing the state of the practice of timber pile retrofitting in Illinois. The study next focused on ; investigating load rating and FRP retrofitting of abutment timber piles as well as studying the long-term performance of FRP-wrapped timber piles. ; Historically, timber piles have been designed for axial loads only. Under this assumption, conventional load rating procedures considered only the ; effect of dead and live loads in determining the capacity of a timber pile. Unlike pier timber piles, abutment piles must resist significant lateral ; forces from earth pressure and surcharge loads in addition to dead and live loads. Currently, there does not exist a separate load rating procedure ; for abutment timber piles. In this study, a load rating method was developed specifically for abutment timber piles. The combined loading effects ; were accounted for by using the allowable stress P–M interaction equation in the National Design Specification for Wood Construction (NDS). In ; addition, a method was developed to account for the effect of FRP retrofits in the load rating. The results showed that deterioration levels as low as ; 10% could lead to unsatisfactory load ratings for abutment timber piles depending on the backfill soil type and equivalent fluid pressure assumed. ; FRP retrofitting, however, increased the load rating of deteriorated abutment timber piles by at least 17%. FRP retrofitting techniques for abutment ; piles were also examined experimentally. Three full-size timber pile specimens with different levels of deterioration were tested. A nondestructive ; stress wave timing method was used to assess the condition of each specimen. FRP retrofits were designed for two of the specimens based on the ; results of the condition assessment. The piles were load tested in the axial direction. First, a specified eccentric load was applied to induce a ; bending moment, then a concentric axial load was applied until the proportional limit. Each pile was tested under a series of eccentric loads varying ; from 10 kips to 35 kips. Timber condition normalized test results showed that the FRP retrofit was able to at least restore the properties of the piles ; to their undeteriorated condition properties. Finally, the long-term performance of FRP-wrapped timber piles was studied by examining their ; performance in uniaxial compression after exposure to long-term degradation. Field-extracted red oak pile specimens with different degrees of ; initial deterioration were used in the study. The initial condition of the timber was assessed through stress wave timing. To simulate natural ; degradation in unretrofitted and retrofitted timber piles caused by environmental exposure in a short period of time, an accelerated aging ; procedure was used. The number of FRP layers and type of resin used (polyester, standard epoxy, and moisture-tolerant epoxy) were varied. ; Results showed that accelerated aging induces significant deterioration in unretrofitted timber piles but the effects are relatively minor in the FRP-wrapped ; specimens. It was also proven that FRP composite can significantly improve the performance of timber piles in terms of peak stress and ; ductility, even after being subjected to extreme degradation.
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• Format:
  PDF
• Funding:
  R27-134
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/31104/dot_31104_DS1.pdf
• File Type:
  [PDF - 3.13 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:a9a8dd25ffcc5b9f381d73c52130e8840966e512badbda3c3d7d1a7477da0846eb809754fdd37da193ffd42133266d0e2847ae7ed8fac356bac0c52b29f02563