What are common technical issues between architects and structural engineers?
One example is diagonal steel bracing and how it affects windows.
Background: I'm a structural engineer thinking about making a course. It will be for architects to understand technical aspects of structures so they coordinate better with us. There are tons of super technical courses out there, so I want to: 1) distill the relevant parts, and 2) make it easy to understand. Architects don't really need to know about biaxial bending, phi factors, finite element analysis, etc.
I'm also new here so please be gentle =)
proto
Dec 12, 21 11:18 pm
finish flr vs top of slab/deck
size of a W10
expansion jts
acceptable deflections by material/sys
exposed structural finishes
waterproofing at foundation details
milkshakelake
Dec 13, 21 12:01 pm
Got it. This is very helpful and I'll go over this stuff. About waterproofing, I always left that up to the architect. I guess I need to read about it more.
Jovan Millet
Dec 13, 21 7:34 am
I don't know if this is what you'd consider technical or not, but here's my shortlist that I come across with my structural engineers:
1. T.O. wall, deck, etc. heights. My engineers never indicate these on their structural drawings, and I've heard all the arguments about "Oh well it's the Architect's scope because they're the ones determining the building's height", but at the same time, I'd rather the T.O. heights be indicated on structural drawings, since that's where the framers, masons, etc. will be looking most often when they're doing their work.
2. Clearances and assemblies which modify that T.O. height. I know that my bearing height for wood trusses on top of a stud wall is (generally) only dictated by where the top plate goes. But when it comes to things like steel beams or masonry which connect to wood trusses, I've had almost as many variations for where that truss will bear as I've had engineers. I'd love to hear that explained in a way that I can intentionally plan for and understand when I'm thinking about my building/ceiling heights.
3. X bracing...in my part of the country, this is a huge thing because of our massive wind loads during hurricane season. Yet it's always a struggle in our design and coordination work to easily determine a rule of thumb for where we will need x bracing with ground level wood stud walls. Sometimes it's equal spacing around a core; sometimes it seems like we'll need it around the perimeter, and other times, our engineer will surprise us by saying we won't need it where we thought we did. It'd be great if we could get a close estimate with some rule having to do with building size, free spans, etc., or whatever the greatest determining factors are.
milkshakelake
Dec 13, 21 12:02 pm
1. I think structural engineers universally don't show T.O. heights because it creates a coordination headache if things change. I tell drafters to remove the elevations when they show it.
2. Every engineer has a different approach for calling out the top of beam, which can get confusing. I didn't know this was an issue, so thanks for that. Generally, all beams should be flush with the bottom of deck unless there's a specific reason to drop a beam, and then the engineer has to make it very clear on plans and sections.
3. Lateral design varies like crazy between engineers. Some just know more than others; it's like going to a good or bad mechanic. Generally, putting bracing around the perimeter and stairs is good practice. I'll definitely put together some rules of thumb, though this is pretty hard since projects vary so wildly.
RJ87
Dec 13, 21 10:29 am
I'm coordinating structural right now for a project where the structural engineer deferred all stud framing to the "delegated engineer". What kind of cop out is that lol. But really our biggest issue with coordination isn't understanding, quite frankly it doesn't make a difference to me as long as it doesn't drive costs into oblivion, it's just that anytime we branch out & use new engineers the drafting is awful so it takes 3 times as long to coordinate the drawings.
Non Sequitur
Dec 13, 21 11:44 am
That's typical for us. Structural does the real steal framing and footings/foundations and any structural steel stud is the responsibility of the sub-trade. Works out because the Arch specifies the stud size and the sub-trade gets their p.eng to stamp the gauge for height of wall. We make this requirement very obvious on our tender docs.
milkshakelake
Dec 13, 21 12:10 pm
If the studs are load bearing, then the structural engineer should do it. If not, most of the time it's reasonable to sub out non-structural studs (like for facades). But a good structural engineer shouldn't be subbing out load bearing stud design.
About drafting standards, I guess there's nothing I could do about that. It all depends if the structural engineer's upper management cares about quality control and presentation.
Non Sequitur
Dec 13, 21 4:45 pm
^Not every project has a struc p.eng on the team. Loads of interiors and fit-ups rely on the trades to do their own structural drawings.
Non Sequitur
Dec 13, 21 11:46 am
I'd be more interested in p.eng who do the calcs on the first day instead of just copying whatever worked on their last project. It makes my day easier since I don't have to ask them to cut the braces by half or reduce the joists and wind girts. Funny how everytime I ask if something can be shorten or reduced it's magically possible.
milkshakelake
Dec 13, 21 12:15 pm
Looks like you're using the wrong engineers. A good one will maybe be able to cut things down by 10% since they leave a small margin of safety. But cutting something by half tells me they didn't do any calculations, which they're getting paid for.
Non Sequitur
Dec 13, 21 12:20 pm
it's very typical with all P.eng in my area. Few will do the calcs until the arch takes the time to question the sizes... then almost by magic, everything I ask for is possible.
proto
Dec 13, 21 4:21 pm
i had similar experiences with schematic engineering back in my bigger office/project days
mightyaa
Dec 13, 21 4:46 pm
Or one that presents possible options. Like "If you use a girder here, then we can use smaller joists. Or just a simple beam. Or a PT slab. Or....." To talk through it and the impact instead of just using the simplest design for them to draw up and design. I didn't hire a drafting service, I thought I hired a licensed design professional.
bowling_ball
Dec 13, 21 7:35 pm
I work with a very busy structural firm that goes so overboard that we invented a corporate motto for them: "When triple redundancy isn't enough." Their president got a laugh out of that one when I told him. It's very common to over-engineer things here.
shellarchitect
Dec 13, 21 12:17 pm
lintels for doors and larger mech opening seem to be a constant source of concern for me. Somehow arch and struct never completely agree on lintel locations and type.
milkshakelake
Dec 13, 21 5:46 pm
Got it, I'll definitely get into this. I think the architect sets the top of window/door and the structural engineer can use all the space between the top of door and bottom of deck for special occasions like transfer beams or long spans. In most cases, some space should be left to run MEP.
JLC-1
Dec 13, 21 3:25 pm
lately, I've been having trouble with the engineer answering the phone.
milkshakelake
Dec 13, 21 5:43 pm
Yeah, I hear this a lot. I think 50% of my business is just because I pick up the phone and answer emails, whereas others don't.
mightyaa
Dec 13, 21 4:10 pm
From the forensic side of building failures due to coordination issues. Deflection is a common one. L/240 (or 120) stuff and various span lengths. All sorts of cracks or failures like plumbing can happen by not designing to allow for differential movement.
A great set of structural I once reviewed actually listed the assumed deflection on the floor/roof framing plans for the member spans. At least then the architect and GC couldn’t claim ignorance. I’d say the vast majority of drywall cracks are simply the failure to note ‘this truss’ will deflect much more than ‘that’ wall.
Along those same lines; most structural engineers absolutely know where it’s probable you’ll see differential movement and can recommend to their architects where to place expansion and/or control joints to allow for this.
b3tadine[sutures]
Dec 13, 21 8:02 pm
I think one challenge is the conservative nature of some of the less structural engineers. When I work with more experienced structural engineers, they have a seasoned sense of what a building will do, and what it won't. But that's not something I think will change. Alright, alright, alright...
What are common technical issues between architects and structural engineers?
One example is diagonal steel bracing and how it affects windows.
Background: I'm a structural engineer thinking about making a course. It will be for architects to understand technical aspects of structures so they coordinate better with us. There are tons of super technical courses out there, so I want to: 1) distill the relevant parts, and 2) make it easy to understand. Architects don't really need to know about biaxial bending, phi factors, finite element analysis, etc.
I'm also new here so please be gentle =)
finish flr vs top of slab/deck
size of a W10
expansion jts
acceptable deflections by material/sys
exposed structural finishes
waterproofing at foundation details
Got it. This is very helpful and I'll go over this stuff. About waterproofing, I always left that up to the architect. I guess I need to read about it more.
I don't know if this is what you'd consider technical or not, but here's my shortlist that I come across with my structural engineers:
1. T.O. wall, deck, etc. heights. My engineers never indicate these on their structural drawings, and I've heard all the arguments about "Oh well it's the Architect's scope because they're the ones determining the building's height", but at the same time, I'd rather the T.O. heights be indicated on structural drawings, since that's where the framers, masons, etc. will be looking most often when they're doing their work.
2. Clearances and assemblies which modify that T.O. height. I know that my bearing height for wood trusses on top of a stud wall is (generally) only dictated by where the top plate goes. But when it comes to things like steel beams or masonry which connect to wood trusses, I've had almost as many variations for where that truss will bear as I've had engineers. I'd love to hear that explained in a way that I can intentionally plan for and understand when I'm thinking about my building/ceiling heights.
3. X bracing...in my part of the country, this is a huge thing because of our massive wind loads during hurricane season. Yet it's always a struggle in our design and coordination work to easily determine a rule of thumb for where we will need x bracing with ground level wood stud walls. Sometimes it's equal spacing around a core; sometimes it seems like we'll need it around the perimeter, and other times, our engineer will surprise us by saying we won't need it where we thought we did. It'd be great if we could get a close estimate with some rule having to do with building size, free spans, etc., or whatever the greatest determining factors are.
1. I think structural engineers universally don't show T.O. heights because it creates a coordination headache if things change. I tell drafters to remove the elevations when they show it.
2. Every engineer has a different approach for calling out the top of beam, which can get confusing. I didn't know this was an issue, so thanks for that. Generally, all beams should be flush with the bottom of deck unless there's a specific reason to drop a beam, and then the engineer has to make it very clear on plans and sections.
3. Lateral design varies like crazy between engineers. Some just know more than others; it's like going to a good or bad mechanic. Generally, putting bracing around the perimeter and stairs is good practice. I'll definitely put together some rules of thumb, though this is pretty hard since projects vary so wildly.
I'm coordinating structural right now for a project where the structural engineer deferred all stud framing to the "delegated engineer". What kind of cop out is that lol. But really our biggest issue with coordination isn't understanding, quite frankly it doesn't make a difference to me as long as it doesn't drive costs into oblivion, it's just that anytime we branch out & use new engineers the drafting is awful so it takes 3 times as long to coordinate the drawings.
That's typical for us. Structural does the real steal framing and footings/foundations and any structural steel stud is the responsibility of the sub-trade. Works out because the Arch specifies the stud size and the sub-trade gets their p.eng to stamp the gauge for height of wall. We make this requirement very obvious on our tender docs.
If the studs are load bearing, then the structural engineer should do it. If not, most of the time it's reasonable to sub out non-structural studs (like for facades). But a good structural engineer shouldn't be subbing out load bearing stud design.
About drafting standards, I guess there's nothing I could do about that. It all depends if the structural engineer's upper management cares about quality control and presentation.
^Not every project has a struc p.eng on the team. Loads of interiors and fit-ups rely on the trades to do their own structural drawings.
I'd be more interested in p.eng who do the calcs on the first day instead of just copying whatever worked on their last project. It makes my day easier since I don't have to ask them to cut the braces by half or reduce the joists and wind girts. Funny how everytime I ask if something can be shorten or reduced it's magically possible.
Looks like you're using the wrong engineers. A good one will maybe be able to cut things down by 10% since they leave a small margin of safety. But cutting something by half tells me they didn't do any calculations, which they're getting paid for.
it's very typical with all P.eng in my area. Few will do the calcs until the arch takes the time to question the sizes... then almost by magic, everything I ask for is possible.
i had similar experiences with schematic engineering back in my bigger office/project days
Or one that presents possible options. Like "If you use a girder here, then we can use smaller joists. Or just a simple beam. Or a PT slab. Or....." To talk through it and the impact instead of just using the simplest design for them to draw up and design. I didn't hire a drafting service, I thought I hired a licensed design professional.
I work with a very busy structural firm that goes so overboard that we invented a corporate motto for them: "When triple redundancy isn't enough." Their president got a laugh out of that one when I told him. It's very common to over-engineer things here.
lintels for doors and larger mech opening seem to be a constant source of concern for me. Somehow arch and struct never completely agree on lintel locations and type.
Got it, I'll definitely get into this. I think the architect sets the top of window/door and the structural engineer can use all the space between the top of door and bottom of deck for special occasions like transfer beams or long spans. In most cases, some space should be left to run MEP.
lately, I've been having trouble with the engineer answering the phone.
Yeah, I hear this a lot. I think 50% of my business is just because I pick up the phone and answer emails, whereas others don't.
From the forensic side of building failures due to coordination issues. Deflection is a common one. L/240 (or 120) stuff and various span lengths. All sorts of cracks or failures like plumbing can happen by not designing to allow for differential movement.
A great set of structural I once reviewed actually listed the assumed deflection on the floor/roof framing plans for the member spans. At least then the architect and GC couldn’t claim ignorance. I’d say the vast majority of drywall cracks are simply the failure to note ‘this truss’ will deflect much more than ‘that’ wall.
Along those same lines; most structural engineers absolutely know where it’s probable you’ll see differential movement and can recommend to their architects where to place expansion and/or control joints to allow for this.
I think one challenge is the conservative nature of some of the less structural engineers. When I work with more experienced structural engineers, they have a seasoned sense of what a building will do, and what it won't. But that's not something I think will change. Alright, alright, alright...