Title:
Lap Splice Tests Using High-Strength Headed Bars of 550 MPa (80 ksi) Yield Strength
Author(s):
Sung-Chul Chun
Publication:
Structural Journal
Volume:
112
Issue:
6
Appears on pages(s):
679-688
Keywords:
bond; head bearing; headed bar; reinforcement
DOI:
10.14359/51687936
Date:
11/1/2015
Abstract:
The provisions on headed bars of ACI 318 have several limitations on bar yield strength, concrete compressive strength, bar spacing, and cover. Moreover, the effects of transverse reinforcement have not been included in the provisions. Twenty-four beams reinforced with lap-spliced headed bars were tested, where 550 MPa (80,000 psi) headed bars, 62 MPa (9000 psi) concrete strength, small bar spacing of db, and transverse reinforcement were used. All specimens showed splitting failure with bottom cover spalling. In contradiction to Section R12.6 of ACI 318-11, transverse reinforcement was shown to be effective in improving the anchorage of headed bars. From regression analyses, a model for predicting the anchorage strength of headed bars in lap splices is proposed, which consists of the components of bond and head bearing, and includes the effects of transverse reinforcement, side cover, and bar spacing on each component.