Case Study: Dublin Port Anchor Block

PROJECT DETAILS

Client: Roadbridge

285 tonnes

75% reduction in onsite labour

Dublin Port Anchor Block

This raft slab is to act as a counterweight for the new docking area at Dublin Port. The 29m long, 16m wide and 3m deep slab had a total of 285 tonnes of reinforcing steel all detailed using Midland Steel’s FasterFix Modular Rebar process. Detailed, delivered and installed modularly, this large raft slab was installed, backfilled and poured in 8 working days saving between 4-6 weeks on the construction programme in comparison to traditional steel fixing.

Due to the design of the reinforcing steel and the strict timeframes of working with the tide level, this project has been identified as an impossible task to complete using traditional steel fixing methods within a workable timeframe. The bottom layer of the raft slab consisted of 6 layers of 32mm rebar with 4 in the top layer with 32mm rebar also. The entire slab was detailed into cages ranging from 1 tonne to 26 tonnes with temporary works all provided by Midland Steel. Through modularising the process with Midland Steel’s FasterFix approach, 75% of the onsite labour was eliminated resulting in a controlled and safe installation process onsite.
What made this project special was the use of Tekla’s feature to mimic the water level height in the 3D model. This feature enabled for the exact times the modular reinforcing steel cages could be placed by using the tide height data and then replicating this data within the model. Without this feature, all planned concrete pours would have been estimated and presumptions would have been made. Tekla software allowed for the entire reinforcing steel installation phase to be visualised and matched with times to plan the working times for this project.

THE PROBLEM

The initial challenge presented was the multiple layered designs required on both the bottom and top layer of reinforcement. In a traditional setting, this challenge would have been a dangerous and almost impossible task to assemble the required rebar detail in situ.

The next challenge was working with the tide. The site conditions and strict timelines would have proved an almost impossible task by using traditional methods.

OUR SOLUTIONS

BIM. Through the use of Midland Steel’s FasterFix and BIM process, Tekla software was used to detail this raft slab. With visualisation and animations, the assembly process was clearly presented to all project stakeholders before any steel was fabricated. This allowed a full safety review and feasibility test to take place both digitally and at Midland Steel’s production facility. Due to the congestion of bars on both layers of the slab, the clash detection tool was vital for productivity. Not only was productivity increased, but health and safety concerns and potential accidents have also been avoided on this project by using Tekla software due to identifying risks before any bars have been fabricated. Assessments of how the modular cages could be assembled had been in constant review during the detailing phases with multiple brainstorming sessions using the BIM model to visualise and plan the assembly process.

Modular reinforcement. Midland Steel has been using Tekla software for over 10 years to detail modular solutions. By following the FasterFix process, a modular solution was detailed to incorporate the number of layers of rebar required into cages and one-way meshes. With a pump running 24/7 to keep the foundation from flooding, the installations had to be optimised at low tides with concrete pours planned as soon as the last cages had been positioned. What made this schedule more complicated was that the Christmas shutdown period was approaching meaning if the foundation was left unpumped, wet clay would have settled at the base around the reinforcing steel cages resulting in an impossible task to remove it all with the rebar in position. The planning of this installation and pour was the most critical part with the Tekla visualisation allowing a full hour by hour schedule as to when the cages could have been dropped into position and working safely on.

 

KEY ACHIEVEMENTS

  • Anchor Block – 285 tonnes.
  • Dimensions – 16m x 29m x 3m, 1,392 cubic m.
  • 26 Pile plugs, 31 prefabricated beams & 56 special meshes.
  • Reduced the construction programme from 5 weeks to 8 days.
  • 75% labour reduced onsite by using modular Midland Steel’s FasterFix approach.
  • Including the tie rods/anchor rods in the detailing and in the preassembled cages saved the contractor 1 week of onsite labour.

MIDLAND STEEL'S ROLE ON THIS PROJECT

Midland Steel was involved during the entire reinforcing steel phase for this project from the detailing through to installation.

Detailing – Used Tekla software to detail 285 tonnes into modular cages and meshed.

Assembly – Through visualisation of the model, our production and technical team were able to come up with solutions on how these modular units could be assembled and transported in a safe manner considering the multiple layers of rebar on the bottom and top layer.

Testing/Trialling lifts/Approvals – All cages were tested and approved at Midland Steel’s manufacturing facility before being delivered to the site. Due to the shape of some of the cages, additional test lifts were carried out to ensure the lifting points were producing a level and horizontal lift. All temporary works were provided by Midland Steel also.

Installation – On each planned installation day, the Midland Steel installation team were onsite to install the modular cages and special meshes. This was coordinated following a strict programme to work with the tide level.

Midland Steel collaborated with the contractor, Roadbridge Ltd. and the consultant engineer, Byrne Looby, throughout this project. The main form of communication was performed through the Trimble Connect platform for approvals, call-offs and general progress tracking.

Midland Steel Reinforcement Supplies are proud to have contributed to this project from the detailing right through to the installation. With early involvement, our BIM and prefabrication experience assisted this project in the installation of the anchor block raft slab at Dublin Port. Our proudest involvement in this particular project was reducing the constriction programme by an estimated 4-6 weeks by using Midland Steel’s FasterFix Modular Rebar process. Over the last 10 year, Midland Steel has built a strong technical team that use Tekla software daily to detail our offsite modular ideas and solutions, this project’s success is based on the capability and experience possessed by this talented team

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