Strengthening of Existing Inverted-T Bent Caps -- Volume 1: Preliminary Design Report uri icon

abstract

  • Inverted-T bent caps are used extensively throughout Texas to economically satisfy geometric constraints. Since the design approach has changed and the traffic volume has increased over the decades, evaluation of existing inverted-T bent caps is needed. The research objectives were to assess in-service inverted-T bent caps based on field visits and current design methodologies. Based on the 2014 American Association of State Highway and Transportation Officials’ load and resistance factor design provisions and the Texas Department of Transportation’s Bridge Design Manual, the demands (girder reaction) and the capacities of the ledge to transfer the applied loads to the web were calculated to evaluate the bent cap for the most critical failure modes: ledge shear friction, ledge flexure, hanger, punching shear, and bearing. Since southbound Bent 13 and northbound Bent 22 had the largest demand, those bents were evaluated and were found to be deficient in ledge flexure, hanger, and punching shear. To address these deficiencies, 18 technical concepts to retrofit inverted-T bent caps were proposed. Retrofit solutions include external post-tensioning, steel brackets to provide supplementary load path, fiber-reinforced polymer wrap with anchors, concrete masonry columns, and increased bearing pad sizes. The proposed retrofit solutions were evaluated using a weighted sum model for the experimental test to validate the satisfactory performance of strengthening existing inverted-T bent caps. Six criteria were considered for the assessment of retrofit solutions: strength increase, total cost, constructability, clearance constraints, durability, and ease of monitoring.

author list (cited authors)

  • Hurlebaus, S., Mander, J. B., Birely, A. C., Terzioglu, T., Cui, J., & Park, S. H.

complete list of authors

  • Hurlebaus, S||Mander, JB||Birely, AC||Terzioglu, T||Cui, J||Park, SH

publication date

  • November 2018