Many sewers, drains and culverts are not perfectly circular, which can lead to over-design in renewal. Finite Element Analysis is enabling Interflow to offer solutions that are more fit for purpose, lower cost and more sustainable.
For many non-circular pipes running below the ground across Australia, the reality of their renewal is imperfect.
If a pipe is perfectly circular then standards, specifications and renewal methods are well documented and accepted. The same can be said for pipes that have deformed to a uniform oval shape within a limited range.
However, as soon as a pipe’s internal shape deflects outside strict parameters, the most efficient and sustainable solutions have been more difficult to design – until now.
At Interflow, there is an innate drive to find world-class solutions to the most complex customer problems. A great deal of thought and research has been put into the effective use of Finite Element Analysis (FEA), a computer-based method that has been used in other engineering sectors, including aerospace and automative, to understand the way complex objects behave under various types of loading conditions.
“Fundamentally, FEA is based on mechanics and mathematics,” says Dr Weigang Wang CP Eng, Design Manager at Interflow. “The computer does the calculation and gives us the very best solution.”
The method works by dividing a complex structure into many small, interconnected components, or ‘elements’. Engineers can then use computer simulations to evaluate how each element responds to applied loads, and how all the elements interact to represent the behaviour of the complete structure under different loading conditions.
If an FEA model reveals a liner can be 20 per cent thinner for the same level of performance and efficiency, there is an automatic saving of material, fuel, handling effort and time throughout the entirety of the supply chain and installation process.
It can mean fewer people are underground or on site and are there for less time. This introduces a safety dividend and a community benefit.
When designers use FEA to quantify limits, field teams can be confident in their defined procedures. As a result, risk drops and less resources are required.
Interflow isn’t suggesting that FEA is used on every renewal project. The sweet spot for the technology, Wang says, is in complex edge cases, including non-circular sections, asymmetric deterioration, unusual load paths or where unique pressures, such as staged grouting, couple with structural response.
“In these instances, the traditional methods are not very accurate,” Wang says. “As a result, people might apply conservative inputs to be safe. This will cost more, will take longer, require more resources and from the construction point of view might create more challenges.”
“As we have been making use of this tool on real projects, we have found it produces a more sustainable design solution that carries less risk. It also delivers greater value for asset owners.”
