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Sponsor: TxDOT

PI: Oguzhan Bayrak
Co-PI: Trevor Hrynyk, Juan Murcia-Delso

The design and detailing of reinforced concrete footings supported by a grid of drilled shafts varies greatly on a state, district, and even municipality basis. The Texas Department of Transportation (TxDOT) has attributed the variations to a lack of guidance and standards for the design of shaft-supported footings. This research is intended to refine the two-dimensional strut-and-tie (STM) provisions recently adopted into the AASHTO LRFD STM provisions, and provide the guidance necessary for consistent design of three-dimensional column footings. The research project will provide:

  • Straightforward Design Provisions for Strong, Serviceable Footings: Nodal efficiency factors and reinforcement anchorage requirements will be derived on the basis of large-scale testing and analytical studies. It is anticipated that recommended design process will consist of stress checks at singular bearings and anchorage checks at critical locations of the STM.
  • Optimal Strut-and-Tie Models for Common Load Combinations: A set of generalized strut-and-tie models will be developed for the most common load combinations encountered by TxDOT. Empirically based guidance will accompany the generalized strut-and-tie models to ensure the most efficient placement of model elements.
Implementation of the three-dimensional STM guidelines developed during this project will lead to the construction of highly efficient, durable shaft-supported footings across the State of Texas.