This paper presents an equation to calculate the required development/splice length of reinforcing bars. The equation is based on previous studies on bond between normal strength and high strength concrete and reinforcing bars. The previous proposed equation to predict the bond strength has been modified to account for the effect of rib properties of reinforcing bars. Also, a new parameter to account for the effect of transverse reinforcement on bond strength has been introduced. The comparison between the results of 284 available tests in cases of normal strength and high strength concrete shows that the new proposed model correlates very well with the test results. Using the proposed equation for bond strength, an equation to calculate the development/splice length has been derived. The equation requires providing some amounts of transverse reinforcement along the development/splice length. By providing the calculated value of transverse reinforcement, the proposed development/splice length would result in adequate ductility for beams with spliced bars. The proposed procedure correlates well with the test results.

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