The Service and Ultimate Behavior of Bent-to-Column Joints in TxDOT Substructures

Details

• Creators:
  Wang, Hwa-Ching ; Briscoe, Terence J. ; Kraus, Pavel ; Castano, Juan E. ; Mursel, Seda ; Yu, Yongjae ; Jang, Hansol ; Saqan, Elias ; Zaborac, Jarrod ; Webb, Zachary D. ; Ferche, Anca C. ; Bayrak, Oguzhan
• Corporate Creators:
  University of Texas at Austin. Center for Transportation Research
• Corporate Contributors:
  Texas. Dept. of Transportation. Research and Technology Implementation Office ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Bent-to-Column Joints Bents Bridge Substructures Capacity Design Civil Engineers Columns Crashes Design Capacity Development Length Disaster Resilience Extreme Events Floods Hinges Joint Confinement Joints Length Loss Of Column Plastic Hinge Plastics Reinforced Concrete Transportation Engineers Vehicular Collision

  More +
• Publication/ Report Number:
  FHWA/TX-26/0-7113-1
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Texas
• Edition:
  September 2021 – July 2025
• Corporate Publisher:
  University of Texas at Austin. Center for Transportation Research
• Abstract:
  This research examined the service and ultimate behavior of bridge bent-to-column connections in Texas Department of Transportation (TxDOT) substructures to develop design recommendations for improved structural resilience under extreme events, including flooding, vehicular collision, and loss of column. A three-phase approach was employed. First, analytical studies, including plastic collapse mechanism and nonlinear dynamic analyses, were conducted on typical multi-column bents to quantify the vulnerability of poorly detailed connections and establish the foundation for a capacity-based plastic design approach and an analysis procedure for loss-of-column scenarios. Second, a large-scale experimental program tested thirteen full-scale bent-to-column specimens under lateral loads simulating vehicular collisions. The program explored various reinforcement anchorage types (straight, hooked, and headed bars) and levels of joint confinement. Third, the test results were used to validate nonlinear finite element models that further explained the observed behavior. Experimental findings revealed that TxDOT’s standard connection details, though designed as pinned, are capable of moment transfer without shear failure; the column achieved their nominal moment capacity with reinforcement yielding at the face, exhibiting ductile behavior. Enhanced anchorage (hooked or headed bars) and transverse joint confinement (hoops) were shown to improve moment capacity, post-yield performance, and damage control underservice loads. The study also found that current code provisions for development length are conservative for these applications. Finite element analyses accurately captured the response and identified the embedment lengths required to develop reinforcement yield strength. This research concludes that adopting a capacity-based plastic design philosophy is essential for resilient multi-column bents and connections subjected to extreme events. The findings offer actionable design guidance, including step-by-step procedures and a worked example, enabling bridge engineers to design safer, more robust substructures in future TxDOT projects.
• Format:
  PDF
• Funding:
  0-7113
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:a49c0b68b7bec08a5d85943bd4682fc3272064450a7d9a394bac3a37b67d51cd75785cd64356b410429a5f6988a9420dfad9e3d8a2406870ed5594627890d8bf
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/89058/dot_89058_DS1.pdf
• File Type:
  [PDF - 7.12 MB ]