Dowel Bar Mechanical Splices
Dowel Bar Mechanical Splices
Dowel bar mechanical splices are used to avoid reinforcing bars from penetrating or protruding from forms. They are also known as “tension-compression” mechanical spices, since they can also resist both tension tensile and compression forces.
All of the various systems commercially available consist of serveral components. The coupling component, initially embedded in concrete, is internally threaded and another component, installed after stripping the forms, is externally threaded. The internally threaded component is normally designed to fasten directly to the form face and is usually encased in the first concrete placement. These systems are available in a variety of designs, configurations, sizes, and shapes.
Mechanical Splice Requirement
ACI 318 Chapters 18 and 25 state the requirements for mechanical splices. They are:
TYPE 1
Shall develop in tension and compression as required at least 125 percent of the specifiedf yeild of the bar. Example: For ASTM A615 grade 60 bar: 1.25 x 60,000 psi = 75,000 psi. Therefore, a splice test exceeding 75,000 psi meets the Type 1 requirement for A615 Grade 60 bar.
TYPE 2
Shall conform to Type 1 requirements and develop 100% of the specified ultimate strength of the bar being spliced. Example: For ASTM A615 Grade 60 bar: 1.00 x 90,000 psi = 90,000 psi. Therefore, a splice test exceeding 90,000 psi meets the Type 1 and Type 2 requirement for A615 Grade 60 bar.