# Rebar length calculation

You have three options to calculate rebar length in Tekla Structures:

- Along center line (default method)
- Sum of leg lengths
- Using a formula

### Along center line

Center line length calculation is used by default (when XS_USE_USER_DEFINED_REBAR_LENGTH_AND_WEIGHT is set to FALSE).

Center line length calculation uses actual rebar diameter by default. In the example above, center line length is calculated as follows:

450 – (30 + 14) + 2*3.14*(30+14/2)*1/4 + 250 – (30 + 14) = 670.1

Where:

- 30= bending radius
- 14=actual diameter (12 is nominal)

### Sum of leg lengths (SLL)

Sum of leg lengths calculation bases on straight leg dimensions and it does not take the bending radius into account.

This calculation is used when XS_USE_USER_DEFINED_REBAR_LENGTH_AND_WEIGHT is set to TRUE and XS_USE_USER_DEFINED_REBARSHAPERULES is set to TRUE. In our example rebar length will be:

450 + 250 = 700

If the length value is shown as zero in reports and inquire, you need to define the length in **Rebar Shape Manager** for each shape as follows:

- In Bending schedule fields, right-click
**L**and select**SLL (Sum of leg lengths)**from the pop-up menu.

See the example:Image - Click
**Update** - Click
**Save**

### Using a formula

In **Rebar Shape Manager**, you can also use a formula to calculate the rebar total length.

You need to have XS_USE_USER_DEFINED_REBAR_LENGTH_AND_WEIGHT and XS_USE_USER_DEFINED_REBARSHAPERULES set to TRUE. In our simple example to take the bending radius into account and to calculate the length along the rebar outer surface, select (formula) from the pop-up menu in the **L** and enter the following formula for the length calculation:

S1 + S2 + 2*3.14*(RS + DIA)*1/4

Where

- S1 = straight leg length 1 (406)
- S2= straight leg length 2 (206)
- RS = rounding radius (30)
- DIA=actual diameter (14)

### Hooks

Hooks are taken into account in length and they are calculated just as any other ordinary bent in all the other environments except for US. In US environments the hook dimension is the extra length needed compared to straight bar. This is handled in rebar_config.inp with the setting PullOutShowUSHookDims. For more information, see Reinforcement settings for drawings.

### Accuracy

The accuracy of rebar length dimensions is defined in the rebar_config.inp file. The values can vary in each environment. The values shown below are from *..\Environments\Common\system\rebar_config.inp*.

The following settings define the accuracy and rounding for the leg lengths:

- ScheduleDimensionRoundingAccuracy=1.0
- ScheduleDimensionRoundingDirection="DOWN"

The following settings define the accuracy and rounding for the total length:

- ScheduleTotalLengthRoundingAccuracy=10.0
- ScheduleTotalLengthRoundingDirection="DOWN"

Other settings affecting rebar length calculation:

XS_USE_ONLY_NOMINAL_REBAR_DIAMETER

#### See also