Years of feedback from contractors working on Fibre Reinforced Polymer (FRP) projects has helped reshape the way Wagners Composite Fibre Technologies (CFT) designs its infrastructure systems.
Rather than accepting traditional connection methods as the only option, the engineering team has developed practical solutions that reduce installation time, minimise rework and make FRP projects easier to build.
Wagners CFT Business Development Manager, Robbie Westley, and Site Manager, Ben Brooks-Veivers explain how listening to contractors has driven practical engineering improvements that are making FRP projects faster, simpler and more efficient to build.
“Speaking with our contractors over the years, there have been several recurring themes and feedback received in relation to pain points, bottlenecks and perceived additional time and labour required on site,” Robbie Westley said.
“Some of the feedback we’ve received is that crush blocks can be difficult and time-consuming to install and that there are often too many bolted connections,” Mr Westley said.
“People are also asking what other connection options are available, how to handle off-centre drilled holes, how to reduce the time spent cutting and drilling on site, how to connect to or make use of open sections and what opportunities there are for prefabrication,” he said.
“We’ve taken that feedback on board and have been developing practical solutions to address these challenges, with a focus on simplifying installation, reducing on-site labour and making FRP construction more efficient.”
Pictured – Wagners CFT construction team pushing and gluing crush blocks into FRP members.
Changes to connection design have significantly reduced the reliance on crush blocks, making FRP construction more practical and forgiving on site.
“Crush blocks were once the only option for a bolted connection and this left little to no room for error on site,” Ben Brooks-Veivers said.
“Designs had to be perfect and every step of the installation on site also had to be perfect,” Mr Brooks-Veivers said.
“There was nothing worse than starting construction and finding a pre-drilled and inserted member missing a crush block in the centre,” he said.
“A lot of time these mistakes would result in the member needing to be replaced or remade on site which ultimately was difficult as the stock crush block is made to be tight for when we detail a glued connection, meaning inserting on site is very difficult.”
“Prior to the designs being altered, there were several onsite techniques used to overcome some of the problems.”
“However, ongoing design optimisation has reduced the need for crush blocks in many applications, helping simplify installation and minimise these common site challenges.”
Pictured – Crush blocks installed within FRP members for bolted connections.
Advances in connection design have seen crush tubes become the preferred solution for many applications, improving both efficiency and constructability.
“The increased use of crush tubes across our designs means that an alternative connection solution is now available for most applications, helping to minimise delays and improve flexibility during construction,” Ben Brooks-Veivers said.
“Crush tubes offer several advantages that not only simplify installation on site, but also reduce the likelihood of errors, rework and associated costs,” Mr Brooks-Veivers said.
“The bush connections versatility ensures that connection capacity is less susceptible to reduction when real world conditions deviate from the design intent,” he said.
“Crush tubes are now being used extensively across projects as reflected by the reduced number of cross blocks appearing in hardware packs and design details.”
Pictured – Bushes/crush tubes installed within a preassembled FRP pedestrian bridge.
Understanding the correct installation requirements for crush tube connections is critical to ensuring their performance and reliability in the field.
“While crush tubes offer several advantages, there are still some important considerations to be aware of,” Ben Brooks-Veivers said.
“When drilling FRP members for bush connections, the hole size must be selected to suit the outside diameter (OD) of the bush rather than the bolt diameter,” Mr Brooks-Veivers said.
“For example, an M16 connection that would typically require an 18 millimetre hole when using a crush block will instead require a 22 millimetre hole to accommodate the bush,” he said.
“Another critical requirement is ensuring that the overall length of the bush is one to two millimetres shorter than the overall width of the member.”
“For instance, a 125 x 125 FRP member would require a bush with a maximum length of 123 or 124 millimetres to ensure proper installation and performance.”
Pictured – Wagners CFT construction team preassembling an FRP bridge at the company’s manufacturing facility in Wellcamp, Queensland.
Riveted connections also provide a simple and practical solution for many FRP applications, helping to streamline installation and reduce rework.
“Riveted connections are simple, efficient and easy to install,” Ben Brooks-Veivers said.
“While they may not always provide sufficient capacity for heavily loaded structures, they are often the preferred connection solution for when higher load requirements are not a factor,” Mr Brooks-Veivers said.
“Riveted connections offer several practical benefits,” he said.
“Installation does not require a trade qualification or specialised training, nor is there a need for custom drill jigs or drill shafts.”
“In addition, if installation errors do occur, they are generally easier to rectify and are less likely to cause significant damage to the FRP members, reducing both rework time and repair costs.”
Pictured – Riveted connections within a FRP pedestrian bridge during construction.
Real-world project examples highlight the practical benefits of selecting more efficient connection methods.
“The Bicentennial Boardwalk project components and design consisted of square posts, crush block bearers, crush block posts, tie brace for handrail post connections and part crush block and bush tubes for handrail posts,” Ben Brooks-Veivers said.
“The process to achieve a finished connection takes a total of 26 minutes and at $100 per hour for labour and the project’s total of 120 bearers, you end up having a rough cost of $5,200,” Mr Brooks-Veivers said.
“The Beree-Badalla Boardwalk project components and design consisted of round 178 piles, crush block bearers, bush piles, riveted diaphragms and bush joists for handrail posts,” he said.
“The process to achieve a finished connection takes a total of 22 minutes and at the same $100 per hour for labour and with the project’s total of 240 bearers, you end up having a rough cost of $8,800.”
“At twice the quantity of bears to the Bicentennial Boardwalk, you can see the bush connection is far more efficient and cost effective.”
Pictured – Stage 3 of the Bicentennial Boardwalk in Airlie Beach, Queensland during construction.
Prefabrication is becoming an increasingly important strategy for improving installation efficiency and reducing on-site labour.
“The ability to prefabricate and transport complete or partially assembled bridges or boardwalk components is one of the most effective ways to reduce installation time on site,” Ben Brooks-Veivers said.
“Even when site access limits the transport of large assemblies, there are often alternative prefabrication options that can be developed in collaboration with the production team here,” Mr Brooks-Veivers said.
“Prefabrication is not limited to assembling an entire bridge or boardwalk section,” he said.
“It can also involve completing smaller tasks in the factory such as installing components in advance to reduce the number of rivets that need to be installed on site.”
Pictured – A fully preassembled FRP pedestrian bridge loaded and ready for delivery.
A comparison between two recent projects demonstrates how prefabrication can significantly reduce on-site labour and construction time.
“The Phil Hill Boardwalk project components and design consisted of round 178 piles, crush block bearers, riveted diaphragms and bush handrail joists for handrail post connections,” Ben Brooks-Veivers said.
“By completing 50% of the required rivets in the brackets in the factory prior to delivery, a substantial amount of on-site labour can be eliminated,” Mr Brooks-Veivers said.
“Each 250 x 100 diaphragm contains eight riveted brackets requiring a total of 48 rivets per member across the project. This equates to 21,120 rivets for diaphragms alone,” he said.
“On the Beree Badala Boardwalk project, all 21,120 of those rivets were installed on site.”
“This effectively required a worker to spend almost 2 weeks in the same location solely riveting brackets to the diaphragms.”
“For the Phil Hill project, however, the production team pre-riveted half of the bracket connections before the components arrived on site.”
“As a result, the number of rivets requiring installation during construction was reduced to 10,560, delivering an estimated 6-day reduction in on-site construction time while also improving productivity and reducing labour demands.”
Pictured – The Beree-Badalla Boardwalk on the Gold Coast, Queensland.
As the first projects begin incorporating C channel members, the connection design is showcasing a simpler and more efficient solution for a range of applications.
“We’re now starting to see designs using our C channel members,” Ben Brooks-Veivers said.
“For projects utlising C channel members, there are no crush blocks in the connection details, only crush tubes within the piles,” Mr Brooks-Veivers said.
“Where higher load capacities are not required, this type of connection can be a highly effective and efficient solution,” he said.
“C channel connections offer a range of benefits, with one of the key advantages being their lightweight construction.”
“Many projects are carried out in challenging or remote locations and reducing the weight of the materials can significantly improve site efficiency.”
“Lighter components are easier to handle and install, reducing the physical strain on workers and lowering the risk of manual handling injuries.”
“They also minimise the reliance on heavy lifting equipment and machinery, reducing costs, simplifying logistics and improving access in difficult site conditions.”
Pictured – Wagners FRP C channel members being installed during construction of the Crystalbrook Boardwalk in Byron Bay, New South Wales.
Continuous design optimisation has also led to changes in pile geometry, with round piles delivering greater installation flexibility than traditional square profiles.
“Square piles were once the standard pile design used across all of our projects,” Ben Brooks-Veivers said.
“Today however, round piles have become the preferred option in almost all applications due to the significant practical advantages they provide during installation,” Mr Brooks-Veivers said.
“One of the key benefits of the round pile is the increased installation tolerance they offer,” he said.
“Achieving perfect alignment between two 125 x 125 square piles is particularly hard in hard ground conditions. This was often extremely difficult and time consuming.”
“When this alignment could not be achieved, the consequences frequently involved additional site work such as manufacturing and installing custom-shaped packers between the bearer and the pile to maintain a consistent connection interface.”
“By adopting round piles, these alignment challenges are largely eliminated, resulting in a simpler installation process.”
Pictured – Jindalee Beach Stairs in Western Australia.
Successful FRP projects begin with good design, early collaboration and the use of proven engineering practices.
“Early collaboration between designers, contractors and suppliers is key to delivering successful FRP projects,” Robbie Westley said.
“By referring to Wagners CFT’s design and drafting guides during the design stage, many common issues can be avoided before they reach site,” Mr Westley said.
“Developed from years of engineering experience, these resources outline the most efficient and proven connection methods, while our technical team is always available to provide expert guidance when needed,” he said.
“By combining proven design practices with early collaboration, projects can be delivered more efficiently, with fewer delays, less rework and better outcomes for everyone involved.”
Watch the full webinar ‘The Right Connection: Construction (Part 2)’ featuring Wagners CFT Business Development Manager, Robbie Westley and Site Manager, Ben Brooks-Veivers – https://www.youtube.com/watch?v=y9-7MfX_Shg&t=2513s
For a greater understanding of designing connections, be sure to watch Part 1 of this series ‘The Right Connection: Design (Part 1)’ – https://www.youtube.com/watch?v=BoJaXFmyfsY&t=2999s
Or read the article ‘Optimised FRP connection design makes infrastructure projects faster and easier to build’ – https://www.wagnerscft.com.au/optimised-frp-connection-design-makes-infrastructure-projects-faster-and-easier-to-build/
Read or download Wagners CFT Installation Guide – https://www.wagnerscft.com.au/app/uploads/2024/05/cft_aus-installation-guide_2023.pdf
Watch ‘Tricks of the FRP Trade’ featuring Wagners CFT Custom Build Shed Supervisor, Ted Fechner and Custom Build Team Leader and Carpenter, Guy Hargreaves – https://www.youtube.com/watch?v=8HkHI3OpCzQ&t=6s
