ᐅ Glued laminated timber beam (GLT) / orientation of the laminations

Is that really your site manager? I can hardly believe it.

alive&kicking schrieb:

Our attempts with building experts to identify further defects were unsuccessful; we encountered disappointing professional knowledge.
We will definitely need additional expert advice, that’s clear, but we will first complete the ongoing process to see where we stand.
We are increasingly noticing that our own site manager, to put it mildly, was not always close to the truth, and now the question arises whether there was possible negligence and, if so, how severe it might be.

Additional expert advice here will mainly be needed from your lawyer, so that the court cannot be misled by the experts with similar nonsense as you have been by the previously consulted specialists. What exactly do you mean by “own site manager”? – apparently no expert was involved on site in a supportive role, but only called in afterwards.

alive&kicking schrieb:

Back to the topic of purlins, which by the way are middle purlins.

And what material are the base purlins made of?

alive&kicking schrieb:

You have already helped others in this forum a lot, but if I may ask, where do you get your assessment regarding the square-shaped purlins?

Calling the purlins “square” based on their overall cross-section is misleading when referring to glued laminated timber (glulam).

alive&kicking schrieb:

Okay, I am a layperson, far from being able to really assess this. One theory was that wood glue joints rarely fail at the glue line itself, but rather within the wood, meaning the bond is stronger than the wood itself.
At first, the horizontal “leaf spring” you mentioned makes perfect sense to me. But isn’t it the case that the glue, being stronger, essentially forms a “new horizontal” layer, naturally “interrupted” by the (stronger) glue lines?

I have been a professional for four decades and base my assessment not only on practical experience but also on having attended school long before Pisa, where compulsory education was not merely an entitlement to remain on site during the morning, but also included actively engaging with learning. Therefore, I can write “physics lessons” correctly. The picture instilled in you of the glue layers as some kind of steel-strong laminated package within the board stack is charming but no closer to the truth than your “site manager.” The only correct aspect is that cracks more often occur between fibers rather than along the glued edges of the boards. Your “follow-up question”

11ant schrieb:

Either the applications / load cases differ, i.e., two purlins oriented the same way are performing the same function (so the pair of base purlins), and the third is the ridge purlin, then this can be correct.

has not yet been answered by you.

But I only spoke up here to prevent you from leaving this world uninformed. I need my time for my work as a consultant (preventive, to ensure those I advise do not become victims of charlatans and swindlers and don’t build butcher’s shops), so I chose not to pursue a career as an expert witness. I don’t want the negative energy from other people’s misfortune to spoil my enjoyment of my profession.

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hanghaus2023 schrieb:

Is that really your site manager? I can hardly believe it.

Yes, that is indeed OUR site manager, contracted for work phases 5 to 8 and structural engineering, paid by us.

I agree with @hanghaus2023. Nothing will likely happen if the beams twist.
This cannot be compared to a leaf spring. It is so flexible because the layers are loose and can slide against each other when bending. BSH (glued laminated timber) should not behave like that.
I also cannot find any load table that differentiates based on the installation direction.

For vertical bending stress on the lamellae, the bending strength of homogeneous glued laminated timber (e.g., GL24h) can even be increased by 20%. For combined types (e.g., GL24c), the bending strengths (allowable stresses) are equal in both directions.
So, no problem.

11ant schrieb:

I believe you will especially need your lawyer’s expertise here, to ensure that the court is not misled by the experts with stories similar to those you’ve heard from the previously consulted "experts." What exactly is meant by a "personal site manager"? – apparently, an expert was called in not alongside the process but rather "after the fact."

I just answered about the personal site manager: he is also an expert, even a member of two (!) professional associations. (Irony)

11ant schrieb:

And what are the base purlins made of here?

The base purlins are made of concrete, the ridge purlin is LVL (laminated veneer lumber), installed vertically.

11ant schrieb:

Calling the purlins "square" because of their overall cross-section is misleading when it comes to LVL.

A square is a square, isn’t it? What would be the correct term for LVL if all sides of the purlin have the same length?

11ant schrieb:

You haven’t answered that so far.

Both of the middle purlins serve the same function.

If I came across as rude or offensive in my response, I apologize. I am grateful for any form of support.

Greetings and thanks to everyone for the help so far.