Suitable glulam beam carport?

[Boan]

Hello

I currently have a carport with a storage room, where the carport section is 4.2m wide (as is the storage room) with approximately 20-degree W trusses, concrete tiles. It is 6m long, with two "bays," i.e., two posts on each side with 3m in between.
Today, there is only a 145x45 under the wall plate... and it has sunk significantly. Calculating on building descriptions to make an opening in the outer wall indicates it should be 56x270....
Isn't that a bit much? I don't mind installing it, but I'm trying to understand compared to the weak material that's there now. Built in 1988.
It has sunk by 30mm between the posts...

 

[scorp1on]

Information about snow zone, center distance between rafters, and a rafter drawing would also be helpful to get a more representative load calculation on the beam.

 

[Boan]

Need info on snow zone, center distance between rafters, and a truss drawing would also be good to get a more representative load calculation on the load-bearing beam.

120 c-c, snow zone 1.5. The shape of the truss should matter less. But regular W

 

[scorp1on]

A smaller role indeed, but to calculate how much load is distributed onto the main beam representatively, it is important.

There are different loads on the main beam depending on where the middle support (where the diagonal struts connect to the upper frame) is positioned.

 

[scorp1on]

Is there any other load than the snow load and the concrete tiles that burdens the rafters today (apart from the negligible self-weight of the rafter)? I don't see why a 45x145 C24 support beam wouldn't work...


EDIT:
I forgot about the load from the subframe acting on the support beam. With 45x145 C24, it's far too weak; theoretically, the utilization rate exceeds 100% on all checks. I get a calculated final deformation of 24 mm.

Theoretically, I also get that 56x270 with GL28cs is needed.

 

[justusandersson]

You have a carport that is 4.2x6 meters. The roof is supported by W-trusses with an approximate 20° pitch on c/c 1200 mm. The trusses rest on two rows of columns, each with three columns. The columns are connected by beams that are 45x145 mm. Is this a correct description?

 

[scorp1on]

You have a carport that is 4.2x6 meters. The roof is supported by W-trusses with about a 20° slope on c/c 1200 mm. The trusses rest on two rows of columns, each with three columns. The columns are tied together by beams that are 45x145 mm. Is this a correct description?

That's how I interpreted it

 

[Boan]

You have a carport measuring 4.2x6 meters. The roof is supported by W-trusses with an approximately 20° pitch on c/c 1200 mm. The trusses rest on two rows of columns with three columns each. The columns are connected by beams that are 45x145 mm. Is this a correct description?

Yep, and they are seriously deformed, there is a 120x45 plate running over the 145-rule, so the idea to strengthen it is to glue-screw it against the new laminated beam, where I think it should work with a 56x225.

 

[Boan]

A smaller role, sure, but to calculate how much load is distributed down to the support beam, it's important.

There are different loads on the support beam depending on where the middle support (where the diagonal braces connect to the upper frame) is positioned.

All the force from the roof should be directed down to the support beam, pure physics, nothing disappears. So each truss will press against the wall plate with the same force on both sides, and that is the sum of everything above.

 

[Tsdoesds]

I may not be completely with you here, but isn't it better and easier with pillars directly under the rafters?

 

[scorp1on]

all the force from the roof needs to go down on the bärlina, pure physics, nothing disappears. so each truss will exert pressure on the top plate with the same force on both sides, and that is the sum of everything above.

Excuse me, I thought the trusses also needed to be included... for the bärlina, as you say, a 56x225 GL28cs is sufficient.

Utilization degree moment: 84%
Utilization degree compression trans. perpendicular to fiber: 94.2%
Utilization degree shear: 91%

Initial deflection: 2.44mm
Final deflection: 4.4 mm

 

[justusandersson]

56x225 is sufficient, but not with much margin. If the beams are highly exposed to weather and wind, I would increase to 56x270. An asymmetrical solution of this kind, where only the trusses at the ends rest directly on a pillar, is not optimal.

 

[scorp1on]

56x225 is sufficient, but not with much margin. If the beams are very exposed to weather, I would go up to 56x270. An asymmetric solution of this kind, where only the trusses at the ends rest directly over a column, is not optimal.

It should be fine if you design for climate class 3, kmod =0.65. It reduces the strength quite a bit in addition to safety factors.

 

[justusandersson]

What are your point loads?

 

[scorp1on]

approx. 6.2 kN. Calculated with 0.6 kN/m^2 self-weight for a heavy roof and 1.5 kN/m^2 snow load on the ground.