How does the software consider beam property changes with pre-stressing tendon?
The option for beam property variation can be found in Analysis
Construction Stage Analysis Control Data Beam Section Property
If Change with tendon option is checked, the software considers section property as detailed below:
- For unbonded tendons : The duct area is deducted from the concrete gross area reducing the section property.
- For bonded tendons : The pre-stressing steel property is converted into an equivalent concrete property
as per the modular ratio and added with the concrete cross-section property as shown below.
With Just beam property,
Stress at top fibre generated by Prestress = P/Ac + P.e1/(I/Y1)
With modified beam property,
Stress at top fibre generated by Prestress = P/(Ac – Ast + m.Ast) + P.e2/(I-modified/Y2)