Title:
Tests of Post-Tensioned Concrete Slab-Edge Column Connections
Author(s):
Douglas A. Foutch, William L. GambleE, and Harianto Sunidja
Publication:
Structural Journal
Volume:
87
Issue:
2
Appears on pages(s):
167-179
Keywords:
columns (supports); concrete slabs; connections; flexural strength; flat concrete slabs; post-tensioning; prestressed concrete; shear strength; reinforced concrete; tests; Structural Research
DOI:
10.14359/2689
Date:
3/1/1990
Abstract:
The results of tests of four connections between reinforced concrete exterior columns and post-tensioned slabs are presented. The specimens, at about two-thirds scale, had steel arrangements representative of banded-tendon layouts, and two specimens had many closely spaced tendons while the other two had only a few widely spaced tendons. The connections also contained reinforcing bars typical of those normally used in these cases. Bending and shear forces were applied to cause failure. Both primary bending failures and primary shear failures occurred. The current ACI Building Code (ACI 318-83) recognizes that the precompression in the concrete, expressed as fpc, enhances the shear strength of an interior column-slab connection. The present series of tests indicates that the same benefit of precompression can safely be extended to the edge column-slab connection case. The ACI Building Code places an upper limit of fpc = 5000 lb/in.ý (3.45 MPa) on the precompression that can be utilized in the shear calculation. Two of the specimens in these tests had fpc values considerably higher than this limit, which does not appear to be necessary. The ACI Building Code also limits the useful compressive strength of concrete to fpc = 5000 lb/in.ý (34.5 MPa) for purposes of shear-strength calculations. This limit does not appear to be necessary, since the concrete strengths in these test specimens were considerably higher, and the shear strength prediction equation remained valid.