Tendon Property

Function

Define the tendon properties to be used for post-tension slab analysis and design, including tendon area, friction losses, anchorage slip, bond conditions, and long-term prestress losses.

For PT slab analysis and design, only the Internal [Post-Tension Slab] tendon type is applicable. 

Call

From the Main Menu 

select [Post Tension] tab > [Tendon] group > [Tendon Property]

Input

- To define new or additional tendon properties

Click the Add Button in the Tendon Property dialog box and enter the following:

Tendon Name

tendon name being defined

Tendon Type

Internal (Post-Tension Slab): Tendons are placed within the slab section and stressed after the concrete has hardened. The prestressing force is transferred to the slab through the defined tendon profile and anchorage system.

Material

Select the material properties of the tendon. Click the ... Button to the right to add new or modify/delete previously defined tendon properties.

Tendon Area

Ultimate Strength

Enter the ultimate tensile strength of the tendon material.

Yield Strength

Enter the yield strength of the tendon material.
 

Curvature Friction Factor

To account for the friction loss due to the curvature of tendons

Wobble Friction Factor

To account for the straightness/length effect (imperfection in alignment along the length of the tendon, regardless of straight or draped alignment)

Anchorage Slip (Draw in)

Tendon slippage at the anchor

Begin : slippage at the beginning of the tendon if tensioned here

End : slippage at the end of the tendon if tensioned here

Bond Type

Bonded : Section properties reflect the duct area after grouting

Unbonded : Section properties exclude the duct area.

Set Long-Term Stress Loss

Strand Type

Select the type of prestressing strand used for the tendon. The strand type influences the relaxation loss considered in the long-term prestress loss calculation.

Low-Lax:  prestressing strand with reduced relaxation characteristics, resulting in lower long-term stress loss.

Stress-Relieved:  Prestressing strand with higher relaxation characteristics, resulting in greater long-term stress loss.

Age of Concrete at Stressing

Specify the age of the concrete in days when the tendon is stressed.

Conc. Modulus of Elasticity at Stressing

Specify the modulus of elasticity of the concrete at the time of stressing.

Relative Ambient Humidity (RH)

Specify the average ambient relative humidity surrounding the structure in %.

Volume to Surface Ratio (V/S)

Specify the ratio of concrete volume to exposed surface area.

Average Initial Pre-compression

Specify the average compressive stress induced in the concrete immediately after prestressing.

- Auto:  Automatically calculates the average pre-compression.

Ultimate Creep Coefficient

Specify the ultimate creep coefficient of the concrete. 

Tensioning Method Factor

Specify the factor associated with the tendon-stressing method. 

Shrinkage Constant

Specify the constant used to calculate prestress loss due to concrete shrinkage.

Relaxation Constant (Kre)

Specify the constant used to calculate prestress loss resulting from relaxation of the prestressing tendon over time.

Relaxation Reduction Factor for Other Losses (J)

Specify the reduction factor used to account for the interaction between tendon relaxation and other long-term prestress loss components such as creep and shrinkage.
 

- To modify the previously entered tendon data

Select the tendon from the list in the Tendon Property dialogue box and click the Modify button to change any relevant data.

- To delete the previously entered tendon data

Select the tendon from the list in the Tendon Property dialogue box and click the Delete button to eliminate any relevant data.