• Registered: 2013-01-22
  • Posts: 10

Topic: Post-tension Duct Pressure Testing

I am looking at various FEM programs to use for my research and would like to know if ATENA will be able to do what I need.

I am looking into how the concrete around the post-tensioning ducts react during air pressure testing of the ducts and grouting of the ducts. I want to minimize the cracking around the ducts and would like to run a few different cases to determine which is the most beneficial (Increased longitudinal reinforcement by the ducts, spiral reinforcement around the ducts, duct spacing, and duct size.)

I was wondering if ATENA is able to apply an outward pressure in the duct to the concrete during the air pressure testing and grouting phases? Air pressure testing occurs before and after post-tensioning of the cables and grouting occurs at the end.

Can the post-tensioning loading and pressurization of the ducts be applied simultaneously?

Also, can the post-tension ducts have vertical curvature within the web?

Quote Post 1

  • dpryl
  • CC software developer
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  • Registered: 2007-07-13
  • Posts: 1,107

Re: Post-tension Duct Pressure Testing

If you like to apply a load to the duct surface, you need to model the duct as an opening in the concrete volume. To get a reasonable mesh around the duct (6 elements around the perimeter), I guess only modelling a short duct segment is feasible (e.g., a length of 10x the duct diameter).

For the segment modelled, you probably apply some pressure or prescribed displacement to the segment border surfaces to represent the prestressing, plus maybe a line or surface load representing the cable force in the radial direction.

All loads (except for a few special exceptions) are incremental in ATENA. That means if you first apply the air pressure, you have to remove it by applying the same amount with opposite sign before you start to apply the post-tensioning. Then, you apply the air pressure again (which means additionally to the loads that are already there).

If the ducts have a complicated geometry, you may need to do some simplifications (or possibly complicated calculations) when applying the loads representing the post-tensioning. You may wish to check (or determine) the forces and displacements to be applied by running the analysis of the whole structure with 1-D cables (ducts not modelled).

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