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How to calculate the reinforcing bar length

Last updated March 12, 2019 by Tekla User Assistance tekla.documentation@trimble.com

Software version: 
2019

How to calculate the reinforcing bar length

How to calculate the reinforcing bar length

You have three options how to calculate the reinforcing barreinforcement that represents a steel bar used to reinforce a concrete structure

The steel bars are usually ribbed and they are used to increase the tensile strength of concrete.

length in Tekla Structures :

  • Along center line, which is the default method
  • As a sum of leg lengths
  • Using a formularule stated in a mathematical language

    Formula is part of an equation.

Along center line

The center line length calculation is used by default when XS_​USE_​USER_​DEFINED_​REBAR_​LENGTH_​AND_​WEIGHT is set to FALSE in File menu > Settings > Advanced options.

Center line length calculation uses the actual reinforcing bar diameter by default.

In the example below, the 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)

The sum of leg length calculation is based on the dimensions of the straight legs and it does not take the bending radius into account.

This calculation is used when XS_​USE_​USER_​DEFINED_​REBAR_​LENGTH_​AND_​WEIGHT and XS_​USE_​USER_​DEFINED_​REBARSHAPERULES are set to TRUE in File menu > Settings > Advanced options.

In the example below, the reinforcing bar length is 450 + 250 = 700

If the length value is shown as zero in reports and inquiries, you need to define the length in Rebar Shape Manager for each shape.

To define the length in Rebar Shape Manager :

  1. In Bending schedule fields , right-click in the L cell and select SLL (Sum of leg lengths) from the pop-up menu.
  2. Click Update.
  3. Click Save.

Using a formula

You can also use a formula in Rebar Shape Manager to calculate the reinforcing bar total length.

You need to set XS_​USE_​USER_​DEFINED_​REBAR_​LENGTH_​AND_​WEIGHT and XS_​USE_​USER_​DEFINED_​REBARSHAPERULES to TRUE File menu > Settings > Advanced options.

For example, to take the bending radius into account and to calculate the length along the reinforcing bar outer surface, do the following:

  1. In Bending schedule fields , right-click in the L cell and select (formula) from the pop-up menu.
  2. 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 )

Accuracy

The accuracy of reinforcing bar length is defined in the rebar_config.inp file. The values can vary in each environment.

For example, the values shown below are from a rebar_config.inp file. In the default environmentTekla Structures environment that contains basic example settings that are not related to any standards specific to a country or a region

the file is located in ..\ProgramData\Trimble\Tekla Structures\<version>\Environments\default\system\ folder.

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 reinforcing bar length:

  • ScheduleTotalLengthRoundingAccuracy = 10.0
  • ScheduleTotalLengthRoundingDirection = "DOWN"

Note that also XS_​USE_​ONLY_​NOMINAL_​REBAR_​DIAMETER affects the reinforcing bar length calculation.

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