Advanced Design and Fabrication

Mechanical Splicing of Reinforcement Bars

Challenge Statement Owner:

Background and Current Practice

To splice two reinforcing bars (“rebars”), a coupler is used. Conventional couplers work based on a mechanical principle similar to nuts and bolts: the rebars are screwed into a coupler.

Couplers are difficult to install onsite because the rebars need to be precisely aligned with the coupler during the splicing process. The threads on the rebars and couplers are fine, and thus could be easily damaged during the splicing process. 

After the coupler has been installed on the first rebar, the second rebar is rotated and screwed into the coupler (see illustration below). This task is challenging, because the rebar is both heavy and long, and thus the splicing requires at least three men to carry out.

Process to splice rebar using a conventional coupler

The threading of rebar is also time-consuming and requires different tools to carry out. Below are the steps for rebar threading:

The three steps for the rebar threading process

Opportunity Areas and Key Challenges

We are interested in alternative designs for the couplers or innovative methods of joining two rebars together.

  • The solution must conform to the standards for "Steels for the reinforcement of concrete — Reinforcement couplers for mechanical splices of bar” (SS ISO 15835), especially for the following requirements (more information can be shared upon request to beamp@padang.co) : 1) Tensile strength under static force, 2) Ductility under static force and 3) Slip under static force
  • It must eliminate the need to rotate the rebar as part of the installation process, so that less manpower is required. 
  • It must be applicable to rebars of different thicknesses, ranging from 16 to 50mm.
  • It should ideally not require any threading or other types of processing method to be performed on the rebar. This would save at least 10 minutes per rebar. 
  • It should ideally have a quick installation process of less than 10 seconds per joint.
  • The introduction of any additional tools would need to be further considered for important aspects, such as space, safety and skills requirements. The solution should ideally not require any additional tools for the installation process.
  • A push-and-lock or a press-and-lock system could be considered.

Expected Outcomes

A new approach to joining two rebars together whilst conforming to SS ISO 15835 standards, the solution would ultimately reduce the manpower required to one person. Also, installation time is reduced from more than 20 minutes to less than 10 seconds per joint.  

Resources

Upon request to beamp@padang.co

  • Requirements under SS ISO 15835 - 1 & 2

After selection

  • Technical guidance on current coupler systems
  • Provide tensile test lab 

Q&A Session

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