Placing reinforcing bars cap#5

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Placing reinforcing bars Cap #5. Reinforcing steel - purpose and location in concrete. - About general Concrete is strong in com-pression, but relatively weak in tension and shear. Generally, wherever tension is present, the concrete is reinforced with reinforcing steel. Quality control of both concrete and reinforcing steel is important to demonstrate to the Engineer or Architect that the specified design requirements are met. The compressive strength of the concrete is verified by taking test cylinders as per ASTM. Standard plastic molds are used which form the concrete into test cylinders 6 inches in diameter and 12 inches high. After 7 to 28 days of curing, these cylinders are placed in a laboratory testing machine and crushed in compression, with gauge readings taken on the machine to determine the crushing load. For example, where 3,000 psi concrete is specified, the cylinders after 28 days should break at about 90,000 pounds load, as shown in Fig. 5-1. Shear is a more complex force than simple tension or compression. A common example is a bolted lap joint in steel plates, producing what is called single shear. In reinforced concrete, this is best illustrated by a l...