Montana Department of Transportation

Malcolm “Mack” Long, Director


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Concrete-Filled Steel Tube to Concrete Pile Cap Connections

picture taken under a bridge structure

The Montana Department of Transportation has found concrete-filled steel tube (CFT) piles connected at the top by a concrete pile cap to be a very cost-effective support system for short and medium span bridges. This type of system offers low initial cost, short construction time, low maintenance requirements, and a long service life. While the gravity load performance of these systems is well understood, their strength and ductility under extreme lateral loads (e.g., seismic events) is more difficult to reliably predict using conventional design procedures. The proposed research aims to further develop newly established design and analysis methodologies, and to ultimately ensure the desired bridge performance.

Phase I: Preliminary Investigation

Phase II: Lateral Load and Lateral Displacement

Phase III: Confirmation of Connection Performance

  • Final Report
  • Implementation
  • Project Summary Report
  • Performance Measures Report
    Kappas, L. (2018). Performance and Design of Steel Pipe Pile to Concrete Cap Connections Subject to Seismic or High Transverse Loading
  • "A design aide was developed in Excel to assist with the proposed algorithm and calculations of subsequent internal connection forces between the embedded steel pile and the concrete pile cap, as described in portions of the provided dissertation. This design aide may be useful to assist with design of a pile-to-pile cap connection if used appropriately. The design aide’s results are based on the experimental findings of the research and would require verification for other specific applications. Additional work is ongoing to verify the design of these connections and design aide. Please contact , 406-444-6932, with questions about this design aide and accompanying information."
  • 2016 TRB Annual Meeting Poster

Phase IV: Further Evaluation and Improvement of Analysis and Design

The primary objective of the proposed research is to further validate/improve MDT’s CFST to concrete pile cap connection design/analysis methodologies, and to ensure the efficacy of these methodologies for a wide variety of potential design configurations. Work will begin by identifying potential gaps in the existing design/modeling strategies, and then designing tests that will help close these gaps. Physical tests will then be conducted and analyzed, with the results being used to develop recommendations as appropriate to improve the analysis and design methodologies.

For more information, contact , 802-546-0217.