The variation in section property due to the tendon is neglected. Consideration of transformed concrete section: The manual calculations are in general, done considering the gross concrete section properties. So, when these divisions are not ending at locations where the tendon profile is having a major change in profile equation (Say, at the curvature of a parabolic profile), then loss calculations wouldn’t be at its most accurate value. Internal considerations of software for Prestress calculation: Internally midas Civil, divides the elements with tendon profile assigned to it, into 4 parts and the effects of Prestressing is calculated at a total of 5 points ( inclusive of i and j ends). Unless R is 0, the tendon won’t pass through P2. And this curve would have lines P1-P2 and P2-P3 as tangents as shown in figure to the right, where P1,P2 and P3 are the coordinates entered. Curve type, Round is selected, radius R has to be entered.

No abrupt change in angles at these locations. Curve type, Spline is selected, then the tendon curve would pass smooth connecting the entered coordinates i.e P1, P2, P3 and P4 as on the figure to left. Improper tendon property, - Incorrect number of assigned elements, curve type and reference axis selection - Make sure to input coordinates based on reference axis selected, whether based on element local axis or on global axis system or along a specified curve. Also, confirm the type of bonding of tendon with the duct. Duct diameters to be of adequate size for tendon area - Consideration of relaxation, entries for friction as well as wobble coefficients and the slip. Improper definition of tendon property, tendon profile: The common mistakes in this dialogue box are: -Assigning inappropriate tendon material, improper tendon type. Prestressing force applied at one end or both ends 1. Consideration of time dependent properties of concrete 5.

Consideration of transformed concrete section 4. Internal consideration of the software for pre-stress calculation 3. Improper definition of tendon property or tendon profile 2.

Midas civil manual