Title: Development of a precast concrete bent-cap system
Date: May-June, 2008
Volume: 53
Issue: 3
Page number: 74-99
Author(s): Eric E. Matsumoto, Mark C. Waggoner, Michael E. Kreger, John Vogel, Lloyd Wolf
https://doi.org/10.15554/pcij.05012008.74.99

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Abstract

This paper summarizes the development of a precast concrete bent-cap system, which can connect precast concrete bent caps to cast-in-place concrete columns or precast concrete trestle piles in nonseismic regions. The primary focus of this paper is the anchorage of reinforcing bars connecting the column or pile to the bent cap. Four connection types were explored, including grout pockets, grouted ducts, grouted sleeve couplers, and bolted connections. Reinforcing-bar-anchorage failure modes and capacities for grouted ducts and grout pockets developed during the first phase of a three-phase test program are presented based on 32 pullout tests of no. 6 to no. 11 (19M to 36M) epoxy-coated reinforcing bars. Anchorage capacity for headed reinforcing bars in grout pockets was found to be accurately determined using the concrete-capacity-design equation reduced by a factor of 0.75 to account for grout-pocket cracking. Based on a uniform bond-stress model, development- length equations for straight reinforcing bars in grout pockets and straight and headed reinforcing bars in grouted ducts were conservatively established for design. Grout-pocket specimens using neat grout achieved the same capacity as similar specimens using grout extended with pea gravel. Spiral confining reinforcement enhanced ductility and capacity more effectively than welded-wire reinforcement. Phase 2 and 3 test results, the design methodology, and a precast concrete construction connection specification will be presented in a future publication.

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