RF-CONCRETE Members – Online Manual Version 5

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RF-CONCRETE Members – Online Manual Version 5

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3.6.4 Min Reinforcement

Min Reinforcement

This tab manages the specifications for the minimum and the secondary reinforcement, as well as the parameters for crack width control. The entered data is considered for the ultimate and serviceability limit state designs, but not for the fire resistance design.

Figure 3.36 Window 1.6 Reinforcement, Min Reinforcement tab
Minimum Reinforcement

Two input fields are available for specifying a general minimum reinforcement. You can enter the steel cross-sections for Min As,-z (top) and Min As,+z (bottom). The reinforcement's cross-sectional areas can also be determined from the number of rebars and the rebar diameters. Click the button to open the corresponding dialog box.

Figure 3.37 Import Reinforcement Area from Rebars dialog box

When determining the required reinforcement, it is possible to independently take into account or exclude the Minimum longitudinal reinforcement and the Minimum shear reinforcement required by the standard.

Longitudinal Reinforcement for Shear Force Design

You can choose among three options to decide, which longitudinal reinforcement is applied in the shear force design without shear reinforcement.

  • Use required longitudinal reinforcement
  • The design of shear resistance is carried out with the available tension reinforcement.
  • Use provided longitudinal reinforcement
  • For the design of shear resistance, either the user-defined longitudinal reinforcement or the one suggested by the program is used.
  • Automatically increase required longitudinal reinforcement to avoid shear reinforcement
  • If the required longitudinal reinforcement is not sufficient for the shear force resistance, the longitudinal reinforcement is increased (at most up to the longitudinal reinforcement ratio of 0.02) until the shear force design is satisfied without any shear reinforcement.

You can find more information about these three options in the following article:
https://www.dlubal.com/en/support-and-learning/support/knowledge-base/000655

Secondary Reinforcement

This window section is enabled if you design a provided reinforcement.

The Maximum bar spacing of secondary rebars (which are not structurally required) in the cross-section can be defined by a peak value. The aim of this setting is to find a uniform distribution of bars in the cross-section leading to a secondary reinforcement of T-beam webs or slender rectangular cross-sections.

If you select the Identical diameter as longitudinal reinforcement option, the same (minimum) rebar diameter as for the required reinforcement is used. Alternatively, after clearing the check box, you can select another diameter ds in the list.

Optionally, you can Add corner reinforcement in order to set a secondary reinforcement in all corners of the cross-section. This way, it is possible, for example for I-shaped sections, to arrange a reinforcement outside the web.

Similar to the minimum reinforcement, the secondary reinforcement, if sufficiently anchored, is taken into account for the ultimate limit state design and the calculation of crack widths.