Splice Strength of Epoxy-Coated High Relative Rib Area Bars

Abstract

The effect of epoxy coating on the splice strength of high relative rib area bars with and without confining transverse reinforcement is described. Test results for 47 beam splice specimens containing No. 5, No. 8, or No. 11 (16, 25 or 36 mm) bars with relative rib areas ranging from 0.101 to 0.141 and seven deformation patterns are included in the analysis. Twenty seven of the 47 beam splice tests are reported for the first time. Average coating thickness ranged from 7.1 to 16.8 mils (0.18 to 0.43 mm). Fortythree specimens were bottom-cast and four were top-cast. The test results for the high relative rib area bars are combined with 44 previous splice tests using conventional bars. Epoxy coating was found to have a much less detrimental effect on splice strength for high relative rib area bars than for conventional bars. The average splice strength ratio of coated to uncoated bars C/U is 0.89, compared to 0.74 for conventional reinforcement. C!U is approximately the same for splices with and without transverse reinforcement. The test results of the current study indicate that the development length modification factor required by the ACI Building Code (318-95) and the AASHTO Bridge Specifications (1992) can be reduced from 1.5 to 1.2 for epoxy-coated high relative rib bars.