Structural Engineer Not Providing Connection Detail

[SteveMack]

I have a strange situation where by my plans are now beyond initial building control full plan submission.  They're accepted, had 1 small challenge about a fire rated window.

 

However..

The structural engineer hasn't provided any connection detail for the beams (5 beams 5 columns) but has stated "All beams to be connected with minimum 4 x 20mm bolts" or something to this effect and then stated, steel fabricator to provide connection detail.

 

However the fabricator has said they don't work like this; the structural engineer must provide the connection designs and they will merely suggest alternate solutions if the structural engineers design is difficult or impossible.  They tell me to get another engineer

 

On calling the structural engineer he tells me, get a proper fabricator who have an in house engineer to design the connections as he wasn't paid to do these and it wasn't in his remit.

 

I'm now going in circles with no clear plan of how the hell this extension is getting built

 

Any advice, or guidance as I'm stuck, even the 2 builders I've got quoting are saying it's very odd what's going on.

Edited January 24, 2021 by SteveMack

[Vijay]

I don't know if it's the norm, but I got all the details for steels/connection details and rebar from my SE

[willbish]

Second @Vijay also received all connection details from SE.

 

Any written contract with the SE you can use as leverage? 

 

Alternatively draw the detail up yourself... and see if the fabricators like it.  The detail is likely to be quite standard anyway I'd imagine. Welded plate on the end of the universal column with 4 holes in it

[willbish]

Here's one of mine if it helps

 

[nod]

Your fabricator is correct 

Your SE is lazy 

The Fabricator will follow your drawing without knowing or carrying what the steel is for 

The drawing should show exactly where the holes should be and the size of the bolts needed 

It’s a ten minute job for your SE to sort this out 

 

[Temp]

I agree its the SE job but this fabricator says they offer free advice on connections..

 

https://www.bandssteel.co.uk/steel-fabrication/connections/

 

 

[SteveMack]

So, when I spoke with the SE last and stated you need to supply them to solve this... he said, that’s not what we agreed.

 

I stated, you were contracted to provide all the steelwork detail which although not detailed on our contract.... the general consensus from anyone in the industry  i.e, my builder/fabricator and architect, it includes connection detail.

 

His answer, well that’s your interpretation but that’s not what I provide!

 

 

Also, I wouldn’t mind if it was some simple connections I’d have a go as you suggest but they are all moment connections and 2 involve a 6m 305x305x198 uc connecting to a 400mm deep RHS which is holding up 80% of the gable end of the house.

Edited January 24, 2021 by SteveMack

[Temp]

Think you will have to find another SE.

 

Then I would suggest a letter to... 

https://en.m.wikipedia.org/wiki/Institution_of_Structural_Engineers

 

[SteveMack]

It’s interesting you say that, he’s a chartered engineer too!

[mvincentd]

I had the same problem....connection styles unspecified were decided upon by the fab, then the SE asked to see his drawings and upon seeing them said we couldn't use the chosen method.  Fab was displeased at time spent wasted and suggested SE should have specced in 1st place if he wants to have approval over them, why should the Fab have to speculate.

I totally sympathise with the Fab but SE insists it is the common practice.

A similar issue occurred in the build regarding rebar and mesh in the raft which left the steel fixers swearing and getting very moody.....but also saying it happens ALL the time.  If this is the case then why they persist in banging heads rather than communicating better I don't know.

I think for me the core of the problem lie in having an SE firm more heavily involved in commercial projects with more complex SE issues than the average domestic house, they were used to the Fab work ending up in the hands of a more 'sophisticated' Fabricator than the small firm I used.  Thats no excuse however.

[SteveMack]

26 minutes ago, mvincentd said:

I had the same problem....connection styles unspecified were decided upon by the fab, then the SE asked to see his drawings and upon seeing them said we couldn't use the chosen method.  Fab was displeased at time spent wasted and suggested SE should have specced in 1st place if he wants to have approval over them, why should the Fab have to speculate.

I totally sympathise with the Fab but SE insists it is the common practice.

A similar issue occurred in the build regarding rebar and mesh in the raft which left the steel fixers swearing and getting very moody.....but also saying it happens ALL the time.  If this is the case then why they persist in banging heads rather than communicating better I don't know.

I think for me the core of the problem lie in having an SE firm more heavily involved in commercial projects with more complex SE issues than the average domestic house, they were used to the Fab work ending up in the hands of a more 'sophisticated' Fabricator than the small firm I used.  Thats no excuse however.

 

Really weird you say this, the SE has just left a job doing commercial designs from what I can tell.  The pieces of this puzzle are starting to fit together.

 

I should add, in the SE defense a little I have all the ULS moment figures for the connections for they should be; just zero detail on how they should look :(

[Temp]

12 hours ago, Temp said:

I agree its the SE job but this fabricator says they offer free advice on connections..

 

https://www.bandssteel.co.uk/steel-fabrication/connections/

 

 

 

This has a sketch of a moment connection but I guess dimensions are important.

 

Edited January 25, 2021 by Temp

[markc]

23 minutes ago, Temp said:

 

This has a sketch of a moment connection but I guess dimensions are important.

 

That`s an odd steel detail. 

[Temp]

Think its missing a horizontal plate for the regular part of the connection? 

[the_r_sole]

It does kind of depend what the engineer has been employed to do - was the engineer employed to show compliance with the building regulations or were they employed to provide construction details?

I'd expect the SE to do steelwork connection drawings but not  really at Building Regs stage - in the same way as I don't do construction drawings for a building regs application either, I would do a construction set after tender stage and only give critical details at regs/tender stage

 

On most projects we'd also have the fabricators produce drawings of what they are fabricating to be checked before fabrication

Edited January 25, 2021 by the_r_sole

[Gus Potter]

7 hours ago, SteveMack said:

 

Really weird you say this, the SE has just left a job doing commercial designs from what I can tell.  The pieces of this puzzle are starting to fit together.

 

I should add, in the SE defense a little I have all the ULS moment figures for the connections for they should be; just zero detail on how they should look

 

Hope this extra info helps.

 

On larger jobs the SE will often contract to produce the steel schemework / call this a general arrangement. They calculate the various forces, size the members and provide drawings that show the beam/ columns, their sizes, grades etc and finish, paint or otherwise. They also provide a list or show the forces @SteveMackon the connections and what type of connection is required, "simple", "moment".. "wind moment connection"... there are others too.  This allows each fabricator who is tendering to design the connection that is most economic for them to produce. The connection design is often passed back the SE to ensure that it meets say the overall stability requirements of the structure.

 

What is advisable to do if you are an SE is to make sure that the fabricator can actually design and practically fabricate the connection as if not it can be embarrassing. The SE may just rough something out or take an educated guess and make some notes which you may not see. The key here is that you (SE) need to make this clear to the Client in your letter of engagement / brief that this is what you only are providing. This is particularly important when dealing with less experienced Clients.

 

Fabricators come in all shapes and sizes. Some have their own in house structural designers, some don't. It's quite common that the fabricator will come back to the SE and ask "can you do the connection design"  and we will pay you for it as part of our package. We sometimes call this getting novated to the contractor. Essentially, you go and work for the contractor for a while. There are pro's and cons to this.

 

There can be quite a lot of work in designing well balanced and cost effective connections. Once you have done this there can be significant amount more work to be done if you then go on to produce the fabrication drawings that go to the shop floor. Often for example each component plate / beam has its own drawing often called a shaft and plate drawing. You then have what are called assembly drawings. If you have a beam with a plate welded to each end this is an "assembly". All the assemblies are then bolted together to form the frame and you have GA (general arrangement) drawings for this. On bigger jobs and even small ones that big fabricators slip in as filler jobs you may also give them what is called an NC file, (numerical control file) this is actually a normal text file .txt that they can plug pretty much into their drilling and cutting line and so on.

 

But the approach I favour for small domestic works, say knocking down a wall with a beam and columns is to produce all the steel info that a small builder needs to price (tender) easily. They can see what they need to do and not have to worry too much other than check the site dimensions once things are opened up.. before fabrication. You may think this can delay the job but what you do is to book your production slot at the chosen fabricator and thus can deal with last minute minor changes, say a few mm in beam length etc.

 

The steel info is wrapped up in a package, zipped up in a zip file and all they need to do is send the zip file to the fabricators for pricing etc.

 

Below is a GA for a small job.. knocking down a wall with a wind post. Important notes are added so they don't get missed. I have screen shotted parts of the drawing. The fabrication package for this beam and column contains 8 drawings. Often the smaller fabricators buy in the plates / shafts so if you make it easy for them the price comes down and this offsets the SE cost.  All they need to do here is send the plate drawings to the plate supplier, shaft to another, get the components in, weld them up and paint or send to galvaniser.

 

 

 

 

 

 

Here is part of the assembly drawing for the column

 

And here is part of a plate drawing. The title boxes and a little info has been removed to try and avoid identification and so on.

 

 

 

 

 

 

[SteveMack]

That's quite a lot of info to type out, thank you very much.

 

I'll update this in due course when I get some answers out of people.  Approaching 2 more builders tomorrow hopefully they have some new/different fabricators to try.

[Gus Potter]

Hope it helped, although some of it was not specific to you. The main thing here is to keep talking to the SE. There may be an oversight in how the brief has been communicated to you and how you have interpreted it. Some fabricators can be a bit forthwrite too!

 

It may be that a bit of give and take with the SE it will smooth the way.

 

@SteveMack"Also, I wouldn’t mind if it was some simple connections I’d have a go as you suggest but they are all moment connections and 2 involve a 6m 305x305x198 uc connecting to a 400mm deep RHS which is holding up 80% of the gable end of the house. "

 

I'm curious looking at the section sizes as to what you are doing. How all this is connected into the rest of the structure and given the sizes there may be some high loads, more likely you have some kind of sway resistant frame, I'm guessing though.  The UC sections you have look huge for a domestic project unless you have a very big house. The SE may be using these sizes to reduce sway and have designed it as a portal frame with a pinned base connection. But, you can also do these as a box frame with side / top plates and this can reduce the weight of steel and spead the loads more evenly over the founds, more mangeable on site and much easier to drill etc to enable connection to the surrounding structure, thus less labour cost, more opportunity to use standard fixings, straps etc, make onsite adjustments when setting out errors occur, for example..

 

The SE should have provided clear detail showing how the frame is to be connected to the rest of the structure as this is also a safety critical aspect.  The stability system is not something that fabricators generally touch. If this is not clear how the stability and restraint system works.. with all restraint fixings specified / detailed in such a way that it is applicable to your project then it's worth querying. If this detail is not robust then the SE may review and you may find that the issue you have resolves it's self.

 

Just as an aside a 305 x 305 x 198 has a 31.4mm thick flange and a 19.1mm thick web. Consider how you can fix a brick tie say to something that thick, site drill it if you are the joiner with a battery drill and find say that the setting out is a bit off?

 

Hope you can make some progess Steve, the builders may have some good ideas.

 

 

 

 

 

 

[George]

I'm a SE and I don't design steelwork connections unless they're very unusual.

 

It really isn't worth my time or the client's money because a fabricator will want to put the connection together in a manner which may not work with my design. ALso, most connections are just looked up in the SCI books (the green book) and need no input from an SE.

 

If they're any sort of fabricator, they should be used to detailing connections to suit the forces and type shown by the SE. 

 

As I don't do them often, I'd have to charge ~50% more fee for the design of a steel frame if I was expected to include detailed connection drawings.

[ToughButterCup]

Just now, George said:

I'm a SE and I don't design steelwork connections unless they're very unusual.

...

 

Very interesting indeed.

Our SE did design the connections.

[George]

It depends on the scale... if it's one connection then I'll just draw it up using the SCI detail. If it's a frame, then it just isn't worth my time.

 

Connections have a bearing on fabrication and erection and that sits firmly with the steelworker.

[Carrerahill]

On 24/01/2021 at 23:52, SteveMack said:

So, when I spoke with the SE last and stated you need to supply them to solve this... he said, that’s not what we agreed.

 

I stated, you were contracted to provide all the steelwork detail which although not detailed on our contract.... the general consensus from anyone in the industry  i.e, my builder/fabricator and architect, it includes connection detail.

 

His answer, well that’s your interpretation but that’s not what I provide!

 

 

Also, I wouldn’t mind if it was some simple connections I’d have a go as you suggest but they are all moment connections and 2 involve a 6m 305x305x198 uc connecting to a 400mm deep RHS which is holding up 80% of the gable end of the house.

Sounds very odd to me, so he did a spec for the steelwork but not how it actually bolts together! If anything, that is the clever bit, if we were all lucky enough just to be resting beams on solid walls then we could all just consult tables for everything, connections are possibly the most important bit! 

[ToughButterCup]

17 minutes ago, George said:

...

Connections have a bearing on fabrication and erection and that sits firmly with the steelworker.

 

Thank you very much indeed for explaining that.

Ian

[George]

25 minutes ago, Carrerahill said:

Sounds very odd to me, so he did a spec for the steelwork but not how it actually bolts together! If anything, that is the clever bit, if we were all lucky enough just to be resting beams on solid walls then we could all just consult tables for everything, connections are possibly the most important bit! 

 

Structural engineering isn't rocket science... but you need to work out the loads the beam is taking, the bending, shear and deflection that will occur for a given beam size/material, have it comply with Eurocodes/British Standards and Building Regulations, then check what it is sitting on is strong enough, and ensure that the overall stability of the building isn't being compromised.

 

I wish there were a single table I could use to look that up! 

 

Connections are clever/complex (I used to be a bridge engineer where all connections are definitely designed by the SE!) but the forces involved in buildings are pretty low so standardised connections are fine and most fabricators want to detail them themselves, so I don't offer it as a service.

[Carrerahill]

4 hours ago, George said:

 

Structural engineering isn't rocket science... but you need to work out the loads the beam is taking, the bending, shear and deflection that will occur for a given beam size/material, have it comply with Eurocodes/British Standards and Building Regulations, then check what it is sitting on is strong enough, and ensure that the overall stability of the building isn't being compromised.

 

I wish there were a single table I could use to look that up! 

 

Connections are clever/complex (I used to be a bridge engineer where all connections are definitely designed by the SE!) but the forces involved in buildings are pretty low so standardised connections are fine and most fabricators want to detail them themselves, so I don't offer it as a service.

You don't need to tell me... I'm the partner of an engineering consultancy! 

 

I was only making the tongue in cheek point that connections should be supplied and the easy bit, relatively speaking, was the steel/timber spec. As you say they are standardised so standard details can be pulled out the CAD library so not an issue to supply, if all the same it might be 3-4 click on CAD to provide the detail then there is no ambiguity. If you have your calcs setup in the software then you know how you put it together so why not show connections?