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Technical Precast Information
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Disclaimer
Various documents are available through this web site for downloading or reference. Laws and regulations are constantly under review. Standards are being updated. Accepted best practice changes as testing and research continues and further knowledge is gained. Building performance through different events provides more information and expectations change. For these reasons, the documents on this web site are for general guidance and provision of background information only. They must be interpreted and applied by suitably experienced and qualified professionals who are competent to do so. Concrete NZ Precast can take no responsibility for use of any information obtained from this web site or through links from it.

Concrete NZ Precast Publications
In addition to the following, other documents of interest to precast manufacturers are accessible through the Members section.

Lifting, Rigging and Inserts
The Health and Safety at Work Act 2015 and the WorkSafe NZ good practice guide Safe Work With Precast Concrete make it clear there is now a collective responsibility to all aspects of precast concrete handling, including provision of lifting inserts in precast concrete for lifting, handling and erection on site.

The following is an extract from section 10.10 Rigging of the WorkSafe NZ guide:

Current industry good practice requires the precast manufacturer (who is responsible for the lifting design) to provide the erector/rigger (via the main contractor) with proposed rigging solutions. The rigger provides comment and approval, and this is endorsed by the main contractor.

The main contractor may require the precaster to commence production prior to appointing an erector/rigger. Nevertheless, the precaster must provide the contractor with a rigging solution and request comment and approval from the main contractor and their erector/rigger. In situations where the erector/rigger has not at that time been engaged by the contractor, the precaster will provide a workable lifting insert design without input from the erector/rigger and it will be the contractor’s responsibility to ensure the erector/rigger engaged is able to work with the lifting insert arrangement that has been provided.

The rigging solution is normally provided by reference to standard rigging and lifting arrangements, and a table such as the one below on the shop drawings.

Lifting & Handling  
Weight of unit for lifting 4.6 T
Strongback required
Yes / No
Load equalization required
Yes / No
Demould
D7
Loading
L1
Transport
T1
Site erection / rotate
P19

 

 

 

 

 

 

 

 

 

The The rigging information must be provided to the people who require it prior to their handling of the precast items. Although these details may have been provided to the main contractor at approval stage, it may be prudent to also send shop drawings with the lifting and rigging details to the site with the delivery of the precast items and ensuring they are handed to the erector/rigger prior to the items being lifted.

Precast panels may contain inserts for use in the factory, different inserts for handling on site, and different inserts for permanent fixing to the structure. It is important that only the correct inserts are used for each operation. The following clause may be added to the shop drawings.

The lifting devices incorporated by the precaster for in-factory use or for permanent fixing into the structure may only be utilised by others after satisfying themselves that their use is within the recommendations of the manufacturer of the device and the manner of their use does not compromise the safety or integrity of the precast element at any stage.

Precast elements face lifted with 4 lifting points may, in the absence of load equalisation, have the majority of the load carried through only two fixed length slings. The lifting points and the slings should be designed considering this possibility.

Floor & Shell Beam Notes for Designers
This document is not a design guide, but rather covers a number of issues that designers and users of prestressed precast floor systems and shell beams will find helpful.

Rib & Infill Floor Construction Guide
This document covers a number of issues relating to installation of the components and construction of a Prestressed Rib and Infill suspended floor.

New Zealand Standards
The flowing New Zealand Standards are particularly relevant to design and production of precast concrete. They are available, together with updates and amendments, and many other concrete related standards from Standards New Zealand

  • NZS 3101:2006 – Concrete Structures Standard
    Rules applying to design of concrete structures in New Zealand. Applies to all types of concrete construction including prestressed, precast, in-situ, and all elements including beams columns walls, panels, floors etc.
  • NZS 3109:1997 Concrete Construction
    Details relating to construction of concrete elements. Reinforcement details for bending, placing etc. prestressing materials, formwork, concrete materials placing finishing and curing. Including dimensional tolerances.
  • NZS 3114:1987 Specification for Concrete Surface Finishes
    Standard surface finish details for off the form finishes, exposed aggregate surfaces, floors, etc. It includes photos of typical surfaces meeting the different specifications.

Good Practice Guideline
WorkSafe NZ's Safe Work With Precast Concrete has replaced Code of Practice for Handling Transportation and Erection of Precast Concrete.

Overseas Design Guides
Design guides are available from a number of overseas organisations. Full books are available for purchase such as:

The web sites of both these organisations also offer a range of free Technical Brochures covering many aspects of precast concrete.

Technical Reports

  • Hollowcore Test Report is a University of Canterbury paper on performance of connection and seating details for Hollowcore floor systems.
  • Double Tee Flange Support Test
  • Although loop bar flange supports were used in New Zealand for many years, their use in new construction is now no longer permitted. The following is historical for information only and may be of use to those who are reviewing existing buildings. It covers testing of a “Loop Bar” flange supported 300 mm double tee subject to support rotation and simulating frame extension to reduce seating under seismic loading. The testing was carried out by BRANZ.
  • Standard Bridge Beams is Transfund NZ Research Report No 252 New Standard Precast Concrete Bridge Beams.