Tendons

Structural analysis and design of tendons

The structure is modelled in FEA program – AxisVM, RFEM, IDEA Frame. The structure can contain 1D and 2D concrete members, cross-sections and materials, external loads, load cases including load case for prestressing, and load groups. Once IDEA StatiCa Prestressing is started, you select 1D concrete members to be prestressed.

 Then you are navigated through individual design steps:

• input of tendon layout, material and other characteristics of prestressing,
• calculation of loads equivalent to the effects of prestressing,
• design of prestressing forces using load-balancing method,
• calculation of short-term losses of prestressing due to friction, anchorage set and steel relaxation,
• export of equivalent loads to FEA program and structural analysis.

Shape of tendons in exceeded scale.

Equivalent loads and load balancing:

Design of prestressed cross-section

IDEA StatiCa Prestressing/Concrete  are effective tools to perform the design pre-stressed concrete sections according to EN codes:

• the evaluation of extreme internal forces based on selected strategy,
• comfortable automatic or manual input of additional non-prestressed reinforcement,
• calculation of short and long-term losses of prestressing (due to elastic deformation of concrete, steel relaxation, creep and shrinkage of concrete,
• design for axial force, biaxial bending, shear, torsion and combined internal forces,
• ultimate and serviceability limit state design for relevant design situations
• detailed results documentation with reference to design equations used and described in the standard,
• descriptive graphics in printout report.

Limitations:

• The structure does not change its structural system during construction stages. Structural analysis is performed with one structural model only - all tendons are assumed to be prestressed in one moment.
• No external load is applied to prestressed part of the structure before it is prestressed, external load or self-weight can be applied at the same time as prestressing.
• Prestressed beam makes one (integral) structural system or part of such system (not a set of independent members) at the stage of the structure, for which the design of tendon is performed. Examples: one structural system = simply supported beam or continuous beam, part of structural system = primary beam of portal frame.
• Cross-section of concrete 1D members is solid (not composite) and it is cast in one construction stage.