RF-CONCRETE Surfaces Version 5

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RF-CONCRETE Surfaces Version 5

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2.5.8 Minimum Longitudinal Reinforcement

Minimum Longitudinal Reinforcement

The statically required longitudinal reinforcement is now compared to the minimum reinforcement. Unfortunately, none of the standards available in RF-CONCRETE Surfaces provide any regulations on the minimum reinforcement for shells. Therefore, we have to analyze in which constellation of moment and axial force we regard the element as a wall (mainly subjected to compression) or a plate (mainly subjected to bending). The distinguishing criterion is the related load eccentricity ed/h in the ultimate limit state (ULS):

edh = m/nh 


Table 2.2


Moment of linear plate analysis (ULS)


Axial force of linear plate analysis (ULS)


Plate thickness

In a design point, there are moments and axial forces in x- as well as y-direction. Hence, the relative load eccentricity for each design point is the largest quotient from moment over axial force of both directions.

In RF-CONCRETE Surfaces, the following is uniformly specified for all standards:

Table 2.2

Mainly subjected to bending → reinforcement rules for plates

Mainly subjected to compression → reinforcement rules for walls

This rule can be found in EN 1992-1-1, clause 9.3: Solid slabs, and clause 9.6: Walls.

The minimum reinforcements are described in chapter 2.3.7 and chapter 2.4.5 in the reinforcement rules for walls and plates.

In our example, the system is mainly subjected to bending. The following minimum reinforcement is shown in the design details.

Figure 2.77 Minimum Longitudinal Reinforcement

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