When does lighting truss crack? The ULTIMATE safety test!

by Shannon on September 27, 2022

In 2021, Titan AV lighting truss was structurally tested at the Centre for Future Materials. These tests were the biggest of their kind ever conducted in Australia! Let's take a peek...

 

Through this project, you’ll learn how lighting truss is tested and what methods are used to capture the data. We’ll watch unedited destructive tests. Plus, you’ll see behind the scenes as truss is safety tested by a team of structural engineers.

But first… why?

Not All Truss are Created Equal!

Today the quality of truss can vary. Differences in welding, manufacturing and raw materials can make or literally break truss. Truss structures often hold hundreds, if not thousands, of kilos above patrons. With this type of risk, it’s critical to know with 100% assurance that it's safe to use.

“We need to do better, we need to be 100% certain that the truss is going to be safe, it’s going to hold what it says it holds. And to set a standard that ensures better & safer practices around using truss in Australia.”
- Rick Eckert, Head of Titan AV Product Design & Development

Your safety is our number 1 priority! That's why Titan AV truss is independently tested in Australia.

Ensure Quality with Australian Testing

When looking for a testing company, we didn't need to travel far. And as a family-owned Australian small business we value supporting local businesses. The University of Southern Queensland (USQ) may seem an unlikely choice. Yet USQ's Toowoomba campus is home to the Centre for Future Materials (CFM). This facility is a world-leading research centre in advanced composite materials.

CFM has gained a reputation for pioneering research and development in engineered materials. They boast a diverse and experienced team of engineers and researchers. With these resources, USQ was the obvious choice to test Titan AV truss.

"Why not? Let’s push the boundaries. Let’s do it properly & be the best! It’s not a cheap process by any means. But at the end of the day we’re choosing to support a local business (USQ) and we’re happy putting that money back into the Australian economy.”
- Rick Eckert, Head of Titan AV Product Design & Development

Non-destructive structural testing truss spans using three metre lengths of Titan AV 290 box truss.

We break truss so you don’t!

To ensure the quality of Titan AV truss, USQ’s team of structural engineers performed a series of structural behaviour tests. They tested individual truss lengths, truss spans and the raw materials of truss. The engineers studied how much the truss bends, twists and strains under pressure. Furthermore, this data informed simulations to model the most widely used applications of truss.

Why 290 box truss?

290 box (also known as F34 square) truss is the most popular style of aluminium trussing in Australia. This great all-round truss can create very strong structures indoors or outdoors. Capable of rigging weighty AV equipment, it's ideal for events and commercial fitouts. 

How they captured the data...

 

To replicate tests, the engineers used a hydraulic press pump to apply downward force onto the truss. They recorded this force in ‘Newtons’. This unit of measurement is used in the building industry to state safety holding values.  

As a guide, roughly every 10,000 Newtons is equal to 1 Tonnes (1,000 Kilograms) of pressure. That's the weight of a baby humpback whale, saltwater crocodile or 1979 Volkswagen Beetle.

What 1 tonne looks like... equal to the weight of a baby humpback whale, saltwater crocodile or 1979 Volkswagen Beetle.

The team used strain gauges and a specialised iMetrum camera to record the measurements. The camera tracks markings (the ‘+’ symbols) placed on the truss. This displacement data would inform the Digital Image Correlation (DIC) technique. With this, the engineers can calculate how much the truss bends, twists and strains.

We start with non-destructive tests to show intended use.

Non-destructive tests (NDT) are a quality assurance tool. Engineers use them to detect and check flaws in structural components and systems. These tests allow us to determine whether 290 box truss is suitable for its designed use.

Non-destructive testing:

  • 12 metre truss span (4 x 3 metre Titan AV+ 290 box truss)
  • 9 metre truss span (3 x 3 metre Titan AV+ 290 box truss)

Non Destructive Testing truss

To ensure accurate results, USQ’s engineers repeated (x3) the same 3000 Newtons loading. These can account for slight movements in the truss joins that may alter the results.

“They do the same 3000 Newtons loading, which equates to roughly 300KG, they do that three times to set the truss just in case there’s slight bits of movements with the joins which would create a bigger or smaller deflection, then they grab an average of the three.”
- Rick Eckert

 

With that completed, the University of Southern Queensland’s team of engineers prepared for destructive testing.

Disclaimer: These tests were done under strict observation. We do not recommend replicating these professional tests or overloading truss beyond a safe capacity. As always, please consult your structural engineer for advice related to your application.

Destructive testing is just that!

Destructive tests force the material, aluminium truss, to fail under increasing pressure. They find the break-point!

Our Titan AV truss underwent destructive testing in horizontal & vertical directions, because... why not!? Both tests had two variations over the same span. The variations would test if one piece of truss is as strong as two connected pieces.

Destructive testing Titan AV 290 Box Truss:

  • 3 metre piece
  • 1.5 metre x 2 pieces
  • (vertical) 0.5 metre x 2 pieces
  • (vertical) 1 metre piece

 

Let’s take a look as a 3 metre stick of 290 box lighting truss is tested to fail…

 

The truss holds well under tonnes of pressure. Then with 2.5 tonnes of load, you’ll notice the main chord (where pressure is directly applied) starts to bend. Then finally, under 3.2 tonnes of pressure the truss fails.

Lighting truss with a visible crack near the center cross weld.

 

Next, the structural engineers tested two sticks of 1.5 metre Titan AV+ 290 box truss joined together. This test would answer the question…

Are truss joins the weakest link?

It's a popular belief that truss joins are the weakest link in the truss. By testing both single & connected pieces of truss, we’re able to challenge this belief. At the same time, we can compare the effects of loading pressure onto different parts of the truss. With this, we can see how the end couplers would hold up under direct pressure.

 

In this test, the connected truss held 4.2 tonnes of loading before failure. That's a 27% stronger result (over the same span) than the single length of truss.

 two connected pieces of truss with a crack from applying tonnes of force in a safety test

2 x 1.5m Titan AV 290 box truss destructive test results in cracked truss

  

Turns out, crushing truss is not so easy!

With horizontal testing complete, the engineers set up for vertical destructive tests. Which means it’s time to whip out the safety shield and take cover! First up for compression testing are two connected pieces of 0.5 metre Titan AV 290 box truss... 

 

Unlike previous tests, the pressure rose to ten tonnes without any bending of the truss. In the end, it took a whopping 20 tonnes of pressure for the truss to buckle. That's an impressive result by anyone’s standard, especially as the truss didn’t completely collapse.

“That’s a very strong beam! 20 tonnes!? That’s a lot of pressure. When we’re testing structural stuff, when they come to their limit, they (usually) collapse.”
- Daniel Mateus, USQ  

 2 connected pieces of 0.5 metre Titan AV 290 box truss crushed inside a testing facility

2 connected pieces of 0.5 metre Titan AV 290 box truss crushed inside a testing facility

Close up on the crushed join of 2 connected pieces of 0.5 metre Titan AV 290 box truss inside a testing facility

 

Our biggest loading yet!

Next, the team tested a 1 metre length of 290 box lighting truss.

 

This test resulted in an even greater load capacity with 26 tonnes of pressure before failure. Similarly, failure was due to buckling and not a complete collapse of the truss.

titan av truss lengths bent out of shape from 20 tonnes of compression testing

But wait there’s more…

Testing the Raw Material

From here, USQ's team performed destructive tests on individual truss elements. These tests include compression & stress strain tests on the raw material to discover what it can handle before welding. These tests provided a huge amount of data on the structural integrity of the aluminium used to make Titan AV truss.

Four-Point loading flexural test setup

Crushing tube truss to test the individual elements of lighting truss

bent section of titan av truss after destructive testing on individual truss elements.
Crushing tube truss to test the individual elements of lighting truss

Using live data + technology to simulate truss systems

With the physical tests out of the way the team focused on simulations. They used software and live test data to create Finite Element Simulations (FEA). These stage truss system simulations modelled horizontal (3-12m) and vertical (1-6m) spans.

Finite Element Model of the stage truss system. Demonstration of FEA and experimental testing

 Demonstration of FEA and experimental testing.

Diagram showing FE analysis of UDL showing deflection for 3m span

FE analysis of UDL showing deflection for 3m span

With this technology Titan AV is able to provide riggers and structural engineers alike, conclusive safety data to protect against the unexpected.

Put your trust in a truss by Titan AV

We put our truss through some of the most rigorous tests imaginable, so every time you rig with Titan AV you can rest assured it won’t let you down.

Titan AV truss are proudly designed and manufactured by the VFM Group, with over 20 years experience in the event production industry. Put your trust in the only truss independently tested and certified in Australia. Titan AV, the ultimate rigging for the toughest gig.

 

 

Any questions or comments about our truss testing process? Leave us a message below, we'd love to hear from you.


Structural Behaviour of Lighting Truss

This project aims to validate the structural performance of lighting truss through experimental investigations and finite element simulations of the structural behaviour of Titan AV lighting truss systems.

This is a joint venture between the Australian Government Department of Industry, Innovation and Science, the University of Southern Queensland and VFM Group.

Logos for the Australian Government Department of Industry, Innovation and Science, the University of Southern Queensland and VFM Group.

Our collective goal is to improve the safety and use of lighting truss. The project may also suggest new designs and/or materials to enhance the structural and load bearing capacity of truss.


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3 comments
by VFM Group on October 31, 2022

Thanks for your feedback guys!

Craig I assume you’re referring to “Part 4: are truss joins the weakest link” video. If you scroll up the page you’ll find our first destructive test (Part 3) on a single 3m piece of 290 box truss. Tests were performed on both single and connected lengths to compare the effects of applying force to different parts of the truss. With the connected pieces resulting in a 27% stronger load capacity (over the same span) than the single length of truss.

by Craig on October 31, 2022

That was a great test, but I don’t believe it really answered the question: I note that this test showed that the load capacity of the retaining pins is greater than the stretching capacity of a length of aluminium pipe, given that the pins didn’t snap first.
This is also a firm warning to make sure you have all the pins in your truss construction – especially at the bottom cord.
I would like to see a comparative test on a single length of 3m to see where and when it collapses.
I would also like to see a test of a join using bolt-together truss to see how that perform as I suspect it would not sustain the same load before breaking.

Also – I am interested to know – did the unbroken piece on the left sustain any measurable stretch damage?

by Robert James on October 25, 2022

I thought this video was very insightful. Great to see the quality of the product.

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