6.3 Welded Reinforcing Steel and AWS D1.4 Code Compliance

6.3 Welded Reinforcement and AWS D1.4

Verify the approved weld detail and applicable welding code before welding begins. AWS D1.4/D1.4M:2018 covers reinforcing bar to reinforcing bar and reinforcing bar to carbon or low-alloy structural steel. ACI 318-19 Section 26.6.4.2 requires AWS D1.4 for nonprestressed reinforcing bar welding. Section 25.5.7.1 applies the $1.25f_y$ strength requirement to a welded splice in tension or compression as required. A weld used for another purpose has its own approved detail and design criteria.

Match material chemistry to the preheat procedure

Carbon equivalent (CE) helps select minimum preheat and interpass temperatures. Preheat controls the weld thermal cycle and helps reduce cracking risk. Under AWS D1.4/D1.4M:2018 Section 1.5.4, use the appropriate equation with element percentages from the material report:

• Bars other than ASTM A706/A706M: $CE=C+Mn/6$.
• ASTM A706/A706M: $CE=C+Mn/6+Cu/40+Ni/20+Cr/10-Mo/50-V/10$.

A706/A706M-16 limits CE to 0.55%. Its material marking and chemistry alone do not establish conformance of a weld. For bars other than A706, ACI 318-19 Section 26.6.4.2(a) requires supplemental mill-report documentation demonstrating AWS conformance. Match the records to the actual bar heat. AWS Sections 1.5.4.3–.4 address unavailable records and unknown composition. They allow representative chemical analysis and give minimum preheat rules when composition is unknown. For an existing-bar case with no data, verify how those provisions and any governing documentation requirements are satisfied before work proceeds.

For example, a No. 8 A615 bar with carbon 0.32% and manganese 1.50% has $CE=0.32+1.50/6=0.57\%$. In Table 7.2, the No. 7–11 row for CE above 0.55% through 0.65% gives a 200°F minimum. A No. 8 A706 bar with the report value 0.48% falls in the above-0.45% through 0.55% range and uses 50°F under the applicable table row. Check the written procedure and other applicable limits as well.

Read the footnotes with the table. The cold-base-metal note for the entries shown without a table minimum calls for at least 70°F when the base metal is below 32°F. When required, preheat the bar cross section for at least 6 inches on each side of the joint, and verify that the applicable minimum is maintained between passes. For welding to structural steel, check its requirement too and use the higher applicable minimum. The table also calls for natural cooling after welding.

Verify procedure, workmanship and authorization

Use the written welding procedure specification (WPS) required by AWS Section 8.1.1. Check the actual process, joint type, bar material and size, filler metal, preheat and interpass limits, and procedure and welder qualification records. AWS Section 8.1.2.1 generally requires procedure testing and provides a prequalification route for eligible fillet welds other than gas tungsten arc welding when all specified conditions are met. Verify the limits of qualification for the work and the applicable approval for any accepted prior qualification. A welding card alone does not establish coverage of this joint.

Direct butt, indirect butt, lap and T-joints are addressed by AWS Clause 5. Check approved joint preparation, fit-up, alignment, dimensions and backing where specified. Verify the correct filler and its handling. AWS Section 7.9 and Table 7.3 specify low-hydrogen electrode storage, with at least 250°F in storage ovens immediately after sealed containers are opened, and exposure limits that vary by electrode classification. Inspect completed welds against applicable visual criteria and required testing under Clauses 6 and 9.

ACI 318-19 Section 26.6.4.2(b) restricts welding crossing bars for assembly, with an exception at the front face of brackets or corbels or where otherwise permitted by the licensed design professional. AWS Sections 6.2.3 and 7.6 address authorization and requirements for crossing-bar and tack welding. Section 18.2.8 adds seismic restrictions. Section 18.2.8.1 places welded splices in reinforcement resisting earthquake-induced forces outside the zone extending twice the member depth from the column or beam face in a special moment frame or from a critical section where inelastic lateral displacements are likely to cause reinforcement yielding. Section 18.2.8.2 prohibits welding stirrups, ties, inserts or similar elements to longitudinal reinforcement required by design in those systems.

Apply the inspection assignment

Under 2021 model IBC Section 1705.3.1, inspection and inspector qualification follow AWS D1.4. Table 1705.3 item 2 calls for periodic weldability verification of bars other than A706, periodic inspection of single-pass fillet welds up to 5/16 inch and continuous inspection of all other welds. Apply the adopted edition and approved inspection statement. Document unauthorized work and report it to the contractor for correction. Under model IBC Section 1704.2.4, report unresolved discrepancies to the building official and registered design professional in responsible charge before completion of that phase.