Abstract :
[en] While anchor heads are particularly useful in the case of large bars which require significant development lengths, the ACI code provides design guidance for bars #11 or smaller. This paper presents a test of a large deep beam reinforced with a single #18 headed bar. The behavior of the beam is evaluated in comparison to the behavior of a specimen with more conventional reinforcement of 6#8 headed bars, and to the behavior of a specimen with lap-spliced anchor hooks. Despite the extreme detailing of the specimen with a single #18 bar, the beam had the same strength as the specimen with 6#8 bars. The compressive stress in front of the anchor head reached about 1.5 times the compressive strength of the concrete and the stress in the #18 bar reached about 414 MPa (60 ksi) before the beam failed in shear along a diagonal crack away from the anchorage zone. Shear strength calculations according to Appendix A of the ACI code showed that the current strut-and-tie provisions can overestimate the shear strength of deep beams by as much as 23%.
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