Red Seal Ironworker (Reinforcing) Practice Exam

What type of stress do reinforcing bars primarily resist in concrete slabs?

1. Compressive stress

2. Tensile stress caused by external loads

3. Shear stress from lateral forces

4. Bending stress during loading

The correct answer is: Tensile stress caused by external loads

Reinforcing bars, commonly known as rebar, are primarily designed to resist tensile stress in concrete slabs. When concrete is placed, it has high compressive strength but relatively low tensile strength. During loading, the concrete undergoes bending, which induces tensile forces on the bottom side of the slab. This is where the reinforcing bars come into play, as they provide the necessary tensile strength to prevent cracking and structural failure. In scenarios where external loads are applied to a concrete slab, such as live loads or dead loads, the tensile stresses generated can lead to significant strain. By including reinforcing bars in the design, the tensile forces are effectively countered, allowing the concrete to maintain its integrity under these loads. Thus, the role of rebar in concrete slabs is crucial for ensuring that they can withstand the tensile stresses that arise due to external forces. The focus on tensile stress reflects a fundamental aspect of reinforced concrete design, which aims to combine the strengths of both concrete and steel to create a more resilient structural element.