Girders for Beam & Block

[Boyblue]

I've seen mention of girders as part of beam and block but I can't find a video or pictures showing how it's done.  Is a girder able to span 6m and carry the weight of all the beams that would be resting on it?

 

Edited January 18 by Boyblue

[crispy_wafer]

Beams are typically placed on blocks over here and spaced out to suit the loading above and length/width of block infill.  Cutting a channel into foundation blocks for the steel?  Got to ask why?  Is this structural engineer designed? 

[Boyblue]

1 hour ago, crispy_wafer said:

Beams are typically placed on blocks over here and spaced out to suit the loading above and length/width of block infill.  Cutting a channel into foundation blocks for the steel?  Got to ask why?  Is this structural engineer designed? 

As mentioned I haven't seen how the girders are used in conjunction with beam & block, and I'd be curious as to how it works.  The drawing is just a sketch, no engineering involved.  Let's presume the girder is properly sized and attached, the purpose would be to support beams and block that would run perpendicular to the girder.  So that instead of 250kg, 6.85m beams you'd have mor managable 4.36m beams to install.

 

Maybe it's because all the homes here are built slab on gade, but most plans have few internal foundation walls, so opting for Beam & block could add significant cost.  I was just thinking that in a case where the plans have already been approved, having an engineer add the girder detail would be a simple fix, that is if they are designed for that purpose.  Of course the simplest thing to do would be to add the middle wall to the foundation design.

Edited January 18 by Boyblue

[G and J]

From what I've read on here if bnb spans more than 5m there's a definite danger of ‘bounce’.  
 

As a result we're putting an extra foundation (is it called a sleeper wall?) down the middle of the house to reduce beam length.  We will have to manhandle these beams as we cant use a crane (overhead wires) so that helps with that too.

 

Are you thinking of using a beam to save the extra foundation?  

[Boyblue]

On 18/01/2025 at 03:32, G and J said:

From what I've read on here if bnb spans more than 5m there's a definite danger of ‘bounce’.  
 

As a result we're putting an extra foundation (is it called a sleeper wall?) down the middle of the house to reduce beam length.  We will have to manhandle these beams as we cant use a crane (overhead wires) so that helps with that too.

 

Are you thinking of using a beam to save the extra foundation?  

It was because I liked the idea of having manageable lengths plus, I had an issue sourcing a crane that didn't include excess charges. But you've now introduced a new dynamic.  In a situation where the technology is new to folks here, bouncing floors would be a nonstarter, so if we need to include additional support, it will have to be done.  Whether by installing a sleeper wall or a pier with a beam I’ll let the engineer decide the most economical solution.

Edited January 22 by Boyblue

[Temp]

We have a large room and the SE specified two steel beams to reduce the span of the concrete beams.

 

Only issue was the steel beams are a bit taller which could have caused issues with the UFH upstairs. 

 

PS This was a B&B first floor.

Edited January 23 by Temp

[Boyblue]

15 hours ago, Temp said:

We have a large room and the SE specified two steel beams to reduce the span of the concrete beams.

 

Only issue was the steel beams are a bit taller which could have caused issues with the UFH upstairs. 

 

PS This was a B&B first floor.

That must have been some span, did you use standard beams or 215 beams?

[BadgerBodger]

I’m wondering why beam and block is the chosen solution? Especially in an environment where it isn’t  typical (maybe even never used). Is it for an upper or ground floor? In most cases where beam and block isn’t used, my experience is that suspended concrete slabs are used, with a falsework/formwork arrangement to get you where you need to be… is it an upper or ground floor? What is more typically done? 

[Boyblue]

9 hours ago, BadgerBodger said:

I’m wondering why beam and block is the chosen solution? Especially in an environment where it isn’t  typical (maybe even never used). Is it for an upper or ground floor? In most cases where beam and block isn’t used, my experience is that suspended concrete slabs are used, with a falsework/formwork arrangement to get you where you need to be… is it an upper or ground floor? What is more typically done? 

Glad you asked.  It hasn't been used primarily because our source of construction technology is the US, and beam & block is not used there because they've moved more to engineered stuff.  With the additional cost of importation, that stuff is simply too expensive .  Where we tend to differ are in cases where a superior alternative is more cost effective.  It this case, slab on grade is used 100% of the time for our ground floors.  The issue now is that fill is becoming scarce in the capital. That combined with the fact that concrete and steel prices are through the roof, could mean that beam & block may be a viable alternative.   No fill, less concrete, less steel, speedy installation and the alternative to do a floating floor at ground level are all attractive choices.  Fill will be barged from nearby islands so slab on grade will no doubt continue to be most popular but beam and block could gain a foothold.

 

Second story, we use wood beams, suspended concrete, or web joists.  Beam and block would be a welcome alternative there as well.

 

[Temp]

On 24/01/2025 at 02:13, Boyblue said:

That must have been some span, did you use standard beams or 215 beams?

 

We needed two beams because a single central beam would bear on a window and the design of the window made that difficult.

 

Afraid I can't recall how deep the beam are.