Detailing for ductility in reinforced concrete earthquake-resistant structures and the risk of non-ductile failure at lap splices of the larger sizes of reinforcing bars have resulted in increasing use of full-strength butt welds of reinforcing bars. The benefits to be gained from eliminating long lengths of lapping bars and reducing serious congestion are overshadowed, however, by the time and cost (both direct and indirect) involved in making arc welds on site and the necessity for special supervision and testing of the work.