What are the requirements for lap splicing of reinforcement bars?

Lap splice length depends on bar type (tension vs compression), bar diameter, concrete strength, and confinement. For tension splices: Class A splice = 1.0*Ld when bars are staggered and less than 50% spliced at one location; Class B splice = 1.3*Ld when more than 50% spliced. Compression splices are typically 0.5*Ld minimum. Splices should be staggered, not located at maximum stress points, and properly tied. Alternative methods include mechanical couplers and welded splices.