North Carolina Building Contractor License Practice Exam

What is the minimum size of a support bar used for the placement of tendons?

1. Number 6 bar

2. Number 8 bar

3. Number 10 bar

4. Number 12 bar

The correct answer is: Number 12 bar

In the context of concrete structures, support bars serve as reinforcement when tendons, typically used in post-tensioned concrete applications, are placed. The minimum size of a support bar is critical to ensure structural integrity and proper anchorage for these tendons. Selecting a number 12 bar as the minimum size reflects the industry standards that emphasize strength and load-bearing capacity. The number designation indicates the nominal diameter in eighths of an inch; thus, a number 12 bar has a diameter of 1.5 inches. This diameter is deemed sufficient to handle the forces exerted by the tendons and to maintain the overall stability of the structure. When dealing with structural design and integrity, adhering to these minimum requirements is essential to prevent problems like excessive deflection or cracking, which could compromise the safety and performance of the concrete structure. This understanding is critical for anyone in the field of construction or engineering, especially when working with post-tensioning techniques.