Category: Precast Detailing Projects

What is load bearing precast element?

Load bearing precast element is anything that receives load from a precast or structural members and transfers the load to another structural member or precast. These precast elements can also be used along as façade, boundary walls, or for architectural design purposes.

What is non-load bearing precast element?

Non-load bearing precast element is anything that may receive load but must not transfer loads to any other structural members or precast. Normally these kind of walls are used only for partition, façade, boundary walls, or for architectural design purposes

What is Partially-load bearing precast element?

Partially-load bearing precast element is anything that receives load from a precast or structural members and transfers the load to another structural member or precast. But only a portion of precast receives and transfers load and the remaining portions will act as non-load bearing ones. (Single precast element which acts both as load bearing & non-load bearing)

Data’s, panel types  & other details for

Load-bearing element	Non-bearing element	Partially-load bearing element
Grade, can be higher upto 80MPa	Grade enough be 40MPa (UNO)	Grade, can be higher up to 80MPa
Gap between two elements are filled with grouting material of required grade	Gap between two elements are filled with Soft joint caulking only. no grouting.	Gap between two elements are filled with grouting material of required grade, extent of filling is for load bearing portion. Remaining portion will be soft joint caulking only
Dowels to be black finish (UNO)	Dowels to be Galvanized finish	Dowels to be Black or Galvanized finish, as per load bearing extend (UNO)
Dowel length, size & spacing as per Engineer’s requirement	Dowel length, size & spacing as minimum as possible after discussing with Manufacturer or Engineer	Dowel length, size & spacing as per Engineer’s requirement  for LBP portion Dowel length, size & spacing as minimum as possible for NLBP portion
Dowel & Grouting materials will transfer load to adjoining element	Dowel will be used to position the precast element & no grouting material present to transfer load. So loads will not be transferred.	Combination of LB & NLB criteria
No ring seal around the dowel	High density foam ring seal around the dowel	No ring seal around the black dowel High density foam ring seal around the Galvanized dowel
Grouting material will cover the dowel, so oxidation in dowel is negligible	No Grouting material, oxidation in dowel is possible. So high density foam ring seal is used and dowels are galvanized to prevent oxidation in dowel	Combination of LB & NLB criteria
No additional tubes or caps needed	Plastic tube will be placed over upper half of dowel. Compressible cap will be placed over the top of the dowel bar.	Combination of LB & NLB criteria
Connection with slab must	Connection with slab may not needed with respect to engineer requirement	Combination of LB & NLB criteria

This is an image showing how precast panels are propped

Propping parameters

Usually propped at 2/3rd height.

No of props usually 2

if the panels are wide could go to more than 2. But rarely 4.

For Panels which span 2 floors, There could be 4 props. 2 below the floor above and 2 above. When you have such a case you have to show opening on the slab through which the upper props will pass.

How long will the props stay in place.

Usually between 1 to 2 months. It could be longer if the construction pace is slow.

How many props are usually used in a multi storied construction?

Depends on construction speed number of panels.

But the number could be around 200.

With prop hire rate of around $3 per week, you can see that the cost of propping is not very small.
When you are estimating for precast, it may be good to consider how many props will be used and what would the cost of propping for a project

Propping is highly skilled job. Improper prop installation can cause accidents shutting down sites, sending stake holders broke. Not to speak of the harm it does to the site personnel.

Who designs the prop.

Most of the the time props are drafted by the detailer and submitted for approval to the engineer.

Detailer cannot issue panel or propping drawings unless there is an approval from the engineer. The certification from the engineer is a must. Without that shop drawings cannot go for construciton.

Without certification, the propping is no go good, illegal and not fit for purpose.

Insurance companies will not cover if there any issue because of prop failure if the drawings were not certified by a qualified engineer.

This is probably first precast project we have attempted with tekla structures as the tool.

We have done a few with Revit, and lot with Autocad.

There is raging argument with no one really know (unless one has walked in the weeds) which is a better tool

I believe no tool as out of the box is really very good.

Tek1 has been working some using Autocad, develping lot of tools for detailing precast panels.

Once something is very useful, everyone wants to steal that.

Code protection is very vital to maintain any sort of edge.

Estimate precast concrete panels for your quotes

Tek1 provides material take off for precast panels.

Deliverables for Precast MTO

• Marked up elevation and Plans
• Panel break ups considering
  • minimization of mould sizes.
  • Transportation constraints
  • Lifting constraints at factory and site.
  • Buildability
• Concrete volume
• Painting requirements
• Reckli requirements
• Mould requirements
• Reo Weights
• Lifters
• Cast in Plates
• Grout tubes.
• Mesh (Not sq m of Mesh, but based of how many sqm of Mesh to cover N panels)
• Rebar schedule
  • Not every panel is estimated for rebar. Typical panels are calculated and applied across similar.
• Quick turn around.

Note

We do not include ferrules in the take off.