An experimental investigation on contact compression lap splice in circular columns

Due to the rapid development in design of multistory buildings and, because of the variation in stories height with the fixed length of the steel reinforcing bars, steel is usually wasted particularly in columns. Hence, compression lap splice may be used within the column height in order to avoid such waste in steel reinforcement which necessitates the optimization of this splice length.In the ACI 318-11 Provisions, the calculated compression lap splice in members with high strength concrete can be longer than tension splice. Hence, an optimization of compression lap splice would contribute to significant saving particularly in columns. This paper presents an experimental study to investigate the behavior of compression lap splice in circular reinforced concrete columns.The objective of the present investigation is to study the influence of splice length, volume of transverse reinforcement and end bearing condition on the behavior of compression lap splice. The conducted investigation included experimental tests of nine circular columns under uniaxial compression loads. All spliced bars were in contact with each other and with constant concrete cover. Based on the experimental investigation and test results, concluding remarks have been drawn, based on which a design simplified equation for splice length in compression has been developed. A correlation between the experimental and calculated results of the author specimens and other results available in literature, showed a good agreement. Also, the formulas adapted by different codes for predicting the compression lap splice length have been checked with the proposed equation.