Structural Repeating Details

About this free Revit file (RVT file)
Name: Structural Repeating Details
Description: Repeating details included: Block and brick wall, bondek, N12-200, N12-300, N16-200, N16-300, N20-150, N20-200, N20-250, N20-300, N20-350. Reo with bar, precast wall, timber joints: 45×90-450 & 90×45-1200.
Family Category: Drafting View
Author: John
Revit Version: 2015
File Size: 660 kb
Download Files: STRUCTURAL REPEATING_DETAILS.rvt
Preview of Revit Drafting View

Preview of Revit Drafting View

Post Tensioned (PT) Concrete Slabs – How to draw

The drafters drafting survival guide to pre-stressed/post-tensioned concrete slabs.

By Allan

Please note: This information has been compiled by drafters working in the Australian PT concrete slab industry. This information may apply to other countries/systems.

Disclaimer this is information is for a guide only. While this article was complied by drafters actively involved in PT drafting, errors or mis-understandings may occur.

PT_layout_sample

A example of a PT slab drawing from a consulting engineer.

Download this file sample in AutoCAD 2000 format.

What do the Symbols on this Plan Mean?

PT_live_end Live End – At this anchorage the hydraulic jack attaches to the strands and “stresses” them.
PT_Dead_End Dead End – An anchorage cast into the concrete.
PT_No_Tendons_and_Strand_Size Number of Strands, in the circle. And the size of strand, commonly Dia 12.7 or 15.2. Often a cover note can be used: “ALL STRANDS DIA 12.7 U.N.O.”
PT_Pan_Live_End Live End with Pan – Used for surface stressing when an anchorage cannot be placed on a vertical concrete face.
PT_Overhead_Live_End Overhead/soffit position live end. Stressed from the underside of the slab.
PT_Stressing_Coupler Stressing Coupler

Photos from Site

A plastic pan form. Part of a live end with pan.

A plastic pan form. Part of a live end with pan.

PT pan live end as shown cast into a slab.

PT pan live end as shown cast into a slab.

PT mono-strand live end. At the edge of a slab.

PT mono-strand live end. At the edge of a slab.

A photo of PT mono-strand stressed live end. Stressing a concrete wall.

A photo of PT mono-strand stressed live end. Stressing a concrete wall.

A PT multi-strand live end

A PT multi-strand live end


The Two Main Systems of Stressing

1. Mono-Strand System – Strand stressed individually, usually an oval shaped duct with rectangular shaped anchorages. The most common system used for stressing slabs.

2. Multi-Strand System – All strands stressed simultaneously, usually a round duct with square shaped anchorages.

Check-list of what to draw on Consulting Engineering PT drawings

These are the engineering design drawings produced for costing etc. pre shop drawings stage.

  • All anchorage locations (live ends, dead ends, couplers etc.)
  • Size of the strands in the duct
  • Number of strands in the duct
  • High and low points of duct. Dimension is taken from slab soffit to underside of duct. Same PT duct runs can be linked together.

Check-list of what to draw on PT shop drawings

These are the drawings used on site.

  • All anchorage locations (live ends, dead ends, couplers etc.)
  • All PT duct runs
  • Size of the strands in each duct
  • Number of strands in each duct
  • Unique identifying number (per pour) for each PT run
  • Dimensions from grids or walls/columns under to all anchorage points
  • Dimensions to variations in the duct run. I.e. the duct does not go in a straight line from live end to dead end which are dimensioned.
  • Soffit of concrete to underside of duct dimensions at 1 metre spacings

Drafting “Rules of Thumb” and Tips

  • Avoid placing text over the thick lines.
  • Generally anything greater than 6 Dia 12.7 of 5 Dia 15.2 use the multi-strand system. Anything less use the mono-strand system.
  • Double live ends can be used on longer PT runs
    • In band beams > 30m run approx.
    • In slabs > 40m run approx.
    • In distribution or slabs of ground > 50m run approx.
  • Minimum set out dimensions
    • Between live ends: 300mm min horizontal. 100mm min vertical
    • Between Dia 12.7 mono-strand tendons: 150mm min horizontal, 100mm min vertical.
    • Between Dia 15.2 mono-strand tendons: 175mm min horizontal and 125mm min vertical
  • Concrete Cover: PT at low points to be chaired at a minimum cover of 25mm to avoid concrete popping out. At high points 20mm cover for the same reason.
  • Reinforcing bars clashing with tendons should be re-layered in a different order or noted on plan to be installed after the PT tendon has been installed.
  • High points over supports, low points mid-span.

Photos from site before concrete pour

Mono-Strand_in_location

Mono-strand in location

Multi_Strands_in_location

Multi-strand system in location