Longitudinal Reinforcement

In the Longitudinal Reinforcement tab, you can define the reinforcement to be used for the bending and axial force design of the member.

Defining Longitudinal Reinforcement

Positions

This section provides the option to define reinforcement positions for the longitudinal reinforcement. Only one position is preset here, representing a type of "basic reinforcement". You can adjust this preset and also add further positions (see image Defining longitudinal reinforcement), for example, to arrange reinforcement with additional bars in sections. Use the button at the end of the list to create new positions. With the button, you can also copy the selected position and then adjust the copy.

For ribs, you have the option to generate the longitudinal reinforcement in the chord from the surface reinforcement. To do this, click the button at the end of the list. The program then generates the longitudinal reinforcement of the rib member from the surface reinforcement that exists in the connected surface. These positions are displayed in the list but cannot be modified. With the button, you can also deactivate the surface reinforcement.

Parameters

In this section, you can specify the properties of the longitudinal reinforcement. The parameters always refer to the position selected in the 'Positions' list.

Basic Data

Select the 'Reinforcing bar type' in the list. Various options are available for arranging the reinforcement.

Selecting Rebar Type

The options result in the following distribution scheme:

Reinforcing bar type	Arrangement
Symmetrical	Top and bottom identical
Unsymmetrical	Top and bottom different, side reinforcement optional
Uniformly Surrounding	Equal on all sides (for columns)
Line	Symmetrical in one layer (for additional bars)
Single	Single bar (for additional bar)

The inputs in the Reinforcement Parameters category are adapted to the reinforcing bar type.

A "basic reinforcement" is preset. It is arranged 'Symmetrically' with three reinforcing bars of 20 mm each on the top and bottom sides. This reinforcement serves to enable design even without a specific reinforcement definition. However, you usually need to adjust the reinforcement so that the verifications correspond to the real conditions! Otherwise, the program would use the presented basic reinforcement for all verifications.

If you do not adjust the reinforcement and initially want to keep the basic reinforcement, you should evaluate the 'Distribution of required or uncovered reinforcement' after the design. Note that the distribution of required or uncovered reinforcement only considers the ultimate limit state! The verifications for the serviceability limit state and fire resistance necessarily require the reinforcement to be defined as close to reality as possible.

Assign a Material to the longitudinal reinforcement. If you have already defined the appropriate reinforcing steel in the model, it is available for selection in the list.

Selecting Material

You can also create a new material via the button in the input field by accessing the material library in the New Material dialog.

With the 'Reinforcement placed in bent corner of stirrup' check box, you can control whether the reinforcing bars are arranged at the top or bottom stirrup edge or exactly in the radius or the center of the bent corner.

Reinforcement Placed in Bent Corner of Stirrup

This option is particularly interesting for columns. For beams, however, which are mainly loaded with a moment about the y-axis of the member, the reinforcement can be arranged at the top or bottom stirrup edge.

Reinforcement Parameters

The input options in this category are adapted to the Reinforcing bar type.

Rebar Parameters for Unsymmetrical Reinforcement

Specify the 'Number of bars' n_s and the 'Rebar diameter' d_s of the longitudinal reinforcement. If the program is to determine the number or the diameter during the design, select the Auto option.

Automatic Calculation | Number of Rebars and Reinforcement

If the number of bars is to be determined, you can specify the minimum and maximum allowable number as well as the increment Δ_x during the design process. With the priority, you can control for multi-layer reinforcements whether a second layer should only be activated when needed. Reinforcements with the value 1 have the highest priority.

If the program is to determine the rebar diameter, you can specify the smallest and largest possible diameter for the design.

Automatic Determination | Rebar Diameter and Longitudinal Reinforcement

For the reinforcing bar types 'Line' and 'Single', you can also define the offset of the reinforcing bars. This value can be referenced to the stirrup, the concrete cover, or the cross-section edges (see also the Additional Reinforcing Offset category). The graphic provides a good control option here.

Selecting Offset Reference for Additional Reinforcement

Reinforcement Areas

In this category, you obtain information about the cross-sectional areas of the placed reinforcement (see image Reinforcement parameters). This information is helpful if, after an initial calculation, you find that individual verifications are not met with the existing reinforcement. You can then check the distribution of required or uncovered reinforcement, compare it with the information in this dialog, and then adjust the diameter or the number of bars accordingly.

Field Location

In this category, you specify where the 'Field' with the longitudinal reinforcement is arranged in the member. You can define this location with a 'Reference' to the start, the end, or an x-location. Select the corresponding option in the list to set the reference point for the field location.

Defining Span Location with Reference to Member Start ("Absolute" Definition Format)

With a 'Field', you have the option to arrange additional reinforcement in a member section and thus provide locally uncovered required longitudinal reinforcement.

For a reference to the 'Start' of the current member, enter the field distances with positive signs; for a reference to the 'End' of the member, enter them with negative signs.

If the member is divided by a node of the 'On Member' type (which does not separate the member, unlike a standard node), you can also define the field referenced to this internal node.

Defining Span with Reference to Internal Node

Furthermore, you can control with the 'Definition format' whether the distances are to be specified absolutely in length or relatively in percentage.

Specify the 'Start' x₁ and the 'End' x₂ of the field. The 'Span' l_s of the field thus represents the length of the longitudinal reinforcement in the member.

If the program is to adapt the length of the reinforcing bars to the statically required reinforcement areas, select the Auto option. This enables an economical design of the reinforcing bar.

Automatic Determination of Reinforcement | Reinforcement Area

For the automatic determination, the field area must be roughly defined: Specify the minimum and maximum start or end location.

Additional Reinforcing Offset

This category is available for the reinforcing bar types 'Symmetrical', 'Unsymmetrical', and 'Uniformly surrounding'. It allows you to position the longitudinal reinforcement in the member individually.

Reinforcement Offset Referred to Stirrups

Select the 'Offset type' in the list, which regulates the reference of the distances. The following options are available:

• 'From stirrup': The distances e_z and e_y refer to the inner edge of the defined stirrups.
• 'From concrete cover': The offset of the longitudinal reinforcement results as the distance from the outside of the cross-section minus the concrete cover minus the distances e_z and e_y.
• 'From cross-section surface': The offset of the longitudinal reinforcement results as the distance from the outside of the cross-section minus the distances e_z and e_y.

Anchorage Start / Anchorage End

For the anchorage length verifications, information on the anchorage of the longitudinal reinforcement is required. Various options for the 'Anchorage start' and the 'Anchorage end' are available for selection in the list.

Selecting Anchor Type

Specify the 'Anchorage length' l_bd and, if necessary, the 'Bending diameter' d_br for both ends.

Information

Finally, you find the following information on the longitudinal reinforcement of the current position:

• Length of a reinforcing bar L_lr,1
• Length of all reinforcing bars L_lr as sum
• Weight of a reinforcing bar W_lr,1
• Weight of all reinforcing bars W_lr as sum

Graphic

On the right, you see the cross-section of the member; below, the longitudinal section. The functions of the two graphic areas are described in the Shear Reinforcement chapter.