Structural assessment of "d" regions affected by premature concrete deterioration : technical report.

Details

• Creators:
  Mander, John B. ; Karthik, Madhu M. ; Hurlebaus, Stefan
• Corporate Creators:
  Texas A&M Transportation Institute
• Corporate Contributors:
  Texas. Dept. of Transportation ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Bents
  • Bridge piers
  • Concrete bridges
  • Deterioration
  • D cracking
  • Failure analysis
  • Structural analysis
  • Reinforced concrete
  • Strut and tie method
  • Alkali silica reactions
• Publication/ Report Number:
  FHWA/TX-15/0-5997-2
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Corporate Publisher:
  Texas A&M Transportation Institute
• Abstract:
  The current study is a continuation of the earlier study that investigated the effects of Alkali Silica Reaction (ASR) and Delayed ; Ettringite Formation (DEF) induced deterioration on the D-Regions of structures. Of the four near full-scale C-Beam specimens that ; were constructed, and conditioned over time as part of the earlier study, the last specimen (Specimen 3), which was field conditioned ; through the Texas heat along with supplemental water for a period of five years, is the main focus of this study. With time, additional ; cracks caused by ASR/DEF swelling were observed in addition to the load induced cracks. Based on the deterioration data collected ; and observations made on Specimen 3, it was classified to show heavy damage due to ASR/DEF deterioration. The experimental ; test of Specimen 3 which resulted in a brittle shear failure through the beam-column joint, showed a similar failure mechanism to ; the other three C-Beam specimens. The heavy deterioration caused by ASR/DEF deterioration also did not seem to have any effect ; on the load carrying capacity of the specimen. However, the response of the specimen was considerably stiffer and less ductile than ; the earlier tested C-Beam specimens with no, slight, and moderate amounts of deterioration. This is due to the restraint offered to ; ASR/DEF swelling strain by the reinforcement, which causes tensile strains in the reinforcement. This effectively put the concrete ; under a state of active prestress. Although no signs of corrosion are observed in the specimen during the deterioration phase, in terms ; of concrete cover spalling or rust stains in concrete, a considerable amount of corrosion was observed on the reinforcement bars once ; the cover concrete was removed. ; A minimalist semi-empirical analysis technique is developed to model the expansion strains caused by ASR/DEF expansion ; in reinforced concrete. The proposed model takes into account the effects of compressive and tensile prestrains on the expansion ; strains caused by ASR/DEF, in addition to the daily variations in temperature and humidity. This enables the model to capture the ; expansion strains in reinforced concrete structures that are exposed to environmental conditions. The model is validated and applied ; to simulate the expansion strains observed for the C-Beam specimens. Considering the complex nature of the ASR/DEF phenomena, ; the nature of the structure considered, and the variability in the field recorded data, the model simulates the expansion strains quite ; well. ; The Compatibility Strut-and-Tie Modeling (C-STM) technique, which was developed and verified in Phase I of this report, ; is used to model the force-deformation behavior of C-Beam Specimen 3. The expansion strains that are obtained from the ASR/DEF ; model is used to compute the prestress loads to be applied in the C-STM technique to account for the effects of ASR/DEF expansion ; in the model. The C-STM simulates the overall force-deformation and the internal behavior of the structure quite well.
  More +
• Format:
  PDF
• Funding:
  Project 0-5997
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28787/dot_28787_DS1.pdf
• File Type:
  [PDF - 20.69 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:363ef2fefb876aceb3dc4b7616dece07215bccc613acce103f4866fd540647593656e657554145b4bf1e02aebde6519bd05c50d60c44be14b35e98d53e359ac0