SKEW JIG system for HS2 bridge beam production
In Melton Mowbray (UK), FTB – a joint venture of construction giants Freyssinet, Tierra Armada, and Roger Bullivant – commissioned a brand-new, 325-meter long, high-tech precast concrete production facility. This facility will manufacture over 3,600 prestressed bridge beams for England’s 225 km HS2 high-speed rail line.
This enormous project includes the detailing, manufacture, and delivery of the precast prestressed concrete T-beams, I-beams and inverted T-beams measuring up to 33 m in length and weighing up to 100 metric tons to 76 different bridge structures on the N1/N2 section of HS2.
In less than a year, the site in Melton Commercial Park was transformed into a state-of-the-art precast plant. The 10,000 m2 prefabrication area includes an integrated rebar cutting and bending operation, four adaptable 100 m long self-reacting prestressing benches, a vapor curing system and an on-site concrete batching plant, as well as an additional 10,000 m2 storage area.
A brand-new JIG prestressed beam reinforcement assembly
FTB turned to SKEW to help design their production process. Through close collaboration, SKEW looked at the complete production process to find the ideal, most efficient assembly breakdown. Subsequently, an assembly system was developed and supplied for the reinforcement of the prestressed T-beams, I-beams, and inverted T-beam bridge elements referred to above.
By reworking the original JIG system design for this specific project, the Skew engineering team ended up developing a brand-new product line dedicated solely to reinforcing prestressed beams. The open, easy-to-access JIG frames include quick-change features, making it possible to adapt, rearrange and even relocate JIGs to accommodate monthly production demand.
The JIGs are designed for quick deployment, with installation taking only a few hours per unit. The adaptable system allows workers to modify and enhance the configuration from the initial setup through to the ramp-up phase.
SKEW has since supplied six 30 m JIG systems that can be easily adapted to accommodate all beam types throughout the project.
Flexibility
All JIG systems are completely adjustable to accommodate differences in height, width, length, and skew angle, but more importantly the specific reinforcement positions and varying spacings for current and future beam designs.
A combination of different types of gripping components was provided to accommodate the proper spacings, even for skewed beam designs.
SKEW developed and supplied several add-ons to position the less standard beams, including skewed beams and the somewhat more complex edge beam variations. JIG sections can be modified rapidly to prepare the JIGs for the next run of reinforcement cages.
Sections of one JIG system can be utilized to extend the length of another. This allowed FTB to optimize their production area throughout the project.
Chris Cleary, Operations Manager, states: “For this project, we wanted to get the whole process right. Together with the engineers from SKEW we managed to break the whole reinforcement process down into straightforward assembly steps. Due to the complexity and variability of the reinforcement configurations, SKEW implemented the modular assembly JIGs to space out the various types of stirrup groups and allow for fast and effective cage assembly. All stirrup assembly is done offline in a separate assembly bay so that the steel fixers can maximize the speed of the SKEW JIGs. After the full cage is fixed, we add the prestress strands, mold end shutters and the reinforcement spacers. We can then lift the whole cage out of the SKEW JIG and into the mold for the casting process.”
Tim Bowker, Quality Manager, explains: “The project and our contractor have strict quality specifications to adhere to, which made this project a challenge. Through assembly of the reinforcement cages on the SKEW JIG, we can assure the reinforcement is correct and fully quality-checked prior to placement in the molds.”
Mark Booth, Health and Safety Advisor, adds: “Although we ordered the SKEW JIGs specifically for quality control and process efficiency, the jigs have been fantastic from a safety perspective. SKEW designed and manufactured the jigs to cater to various lengths, widths, and reinforcement cage weights so that they provide a solid, robust base which eliminates any risk of overturning.”
Results and conclusions
The joint venture at FTB’s Melton Mowbray plant established for the HS2 project has achieved remarkable success, largely attributed to the integration of cutting-edge technologies. Notably, the SKEW JIG system has been pivotal in not only ensuring the project’s successful execution but also setting a new industry standard for reinforcement assembly in large-scale bridge beam fabrication.
