About the anchorage length of the bottom reinforcement

The anchorage length of bottom reinforcement are the yellow numbers in the print screen below:

The anchorage length is necessary for two reasons:

1. The bottom longitudonal reinforcement is part of the strut-and-tie model used for the shear force. For it to function properly, it needs to be securely anchored. Otherwise the shear force in the beam cannot be derived to the support.
   Since supports are always at the the bottom of the beam, the yellow numbers are only present at the bottom.
2. A second reason is prefabrication. When a beam is prefabricated, it usually beams the beam is partly fabricated in a factory (= bottom reinforcement and stirrups are placed in the factory) and partly cast on site (= top reinforcement is placed on site).
   If continuous anchoring in such a beam is chosen, it often overlaps with the waiting reinforcement present in other elements, like prefabricated columns. As a work-around, you can opt for discontinuous anchoring in the beam. This allows you to determine where the anchoring rods will be placed in the beam on site.

Both situations thus require an anchoring amount. If we focus on the left support the anchoring amount is 318mm². But where you define its corresponding amount of bars, depends on the type of anchoring you’ve chosen:

• If you’ve chosen for discontinuous anchoring , you need to double click the 318mm² and define a sufficient amount in the dialog that appears.
• If you’ve chosen for non-discontinuous anchoring ( or ), you need the blue number to be at least 318mm². Double clicking the 318mm² won’t do it for this case.