Historic Courthouse Steel Brick Lintel

[WEJ83]

Recently did a visual on a 1919 era courthouse. East and West ends are mirrored sunken entrances, with a steel lintel above carrying brick and spanning 20' or so. The lintel itself is obviously deflected approximately 2", however the supported brick above is perfectly level. The bottom mortar joint varies in depth along the length of the lintel to make up the difference. Same condition on both ends of the building.

Trying to resolve in my head the deflection. First thought was that at some point the deflection had damaged the brick and it had been removed and replaced without replacing the lintel. The brick and mortar look original though, although this could have occurred 60, 70, or 80 or more years ago and picking out a repair may be difficult.

Ruling out physical damage or degradation of the lintel because each side is exactly the same.

Another thought was that the lintel was pre-deflected for the dead loads before the masonry was installed. Possibly to allow a lighter or shallower lintel section. Was this possibly a design practice in buildings of this era? or does anyone else have an alternate possible explanation?

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1644550092/tips/Lintel_iw1mmy.pdf[/url]

 

[bugbus]

the lintel was pre-deflected for the dead loads before the masonry was installed. Possibly to allow a lighter or shallower lintel section

I like this theory

 

[kipfoot]

Ruling out physical damage or degradation of the lintel because each side is exactly the same.

My guess is that it's deterioration of the lintel...or perhaps a plate that's hanging from the steel beam (but the steel beam itself is also supporting the masonry). It may be similar on both sides because the detail situation is the same in both places, leading to similar results over the decades. To me, the brick looks like it's been repointed and that this area gets some water running over it.

I think you need to chip out some of the thick mortar to get a better sense of the condition.

 

[hokie66]

Agree with kipfoot. When you rake out that thick mortar, you will likely find pack rust which has deflected the lintel.

 

[phamENG]

The masonry about the lintel has mortar in at least three colors and the mortar packed in between the bottom course and the lintel is a fourth color. It's been repointed and patched several times by the look of it. I think kipfoot covered it well.

 

[WEJ83]

Sorry, maybe not clear enough, but it is obvious that the entire building has been repointed, my point was that it does not look like the brick has ever been completely removed and replaced. If the lintel failed and deflected after installation, then the brick would appear to have had to support itself until the new mortar was repacked in. Not probable on paper but not necessarily out of the question either. Another oddity not mentioned is that the brick on the opposite side of the lintel does not have the wide mortar joint at the bottom, although there is only 1/8" to 1/4" max elevation change across the width of the lintel. The backside brick appears level, but can't be. It has no cracks or signs of damage from movement.

You are right, I shouldn't rule out deterioration. It just seems odd that both sides are identical, even though there are significant differences in exposure to sunlight and wind driven rains on opposite sides of the building. The exposed edges of the lintel plate look clean and fairly sharp however and don't show signs of delamination or expansion from corrosion like I would expect to see.

If it is deterioration, I would expect that the connection (rivets) between the flat plate and the main supporting vertical member corroded and gave way allowing the plate to delect basically under its own self-weight, and the brick somehow supported itself until the mortar was packed in. Doesn't explain the brick on the backside or why both sides failed in exactly the same way meaning the fasteners failed in the same number and pattern.

We will likely recommend exposing enough of the lintel to see if it is damaged. My post was primarily to see if the pre-deflection thought was viable or if someone might know if it was a common practice at that time period. It seems to explain many of the questions, but admittedly the thick mortar at the bottom still looks like some type of patch job.

 

[masonrygeek]

It would be unusual to preload the angle in that era of construction, but its possible. I would guess that this has something to do with rust-jacking and maybe there is enough load above that the rusting forced the angle down and not up. You're going to have to talk with the original mason to know for sure.

 

[dik]

Careful for any unintended issues.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[WEJ83]

Well M-geek I'm definitely not hoping to meet up with the original mason anytime soon.

Rust-jacking the lintel downward is definitely a possibility, I just can't quite rationalize the exact same deflections and conditions at two locations by happenstance.

 

[WEJ83]

dik - Care to expound any?

 

[dik]

When you are not certain about a structural response, in remedying the problem, you may create other issues. It would be nice to determine the cause. If rusting is the problem, there may be others due to the ingress of water on a masonry structure. Off the top I cannot determine the cause of the problem. I've encountered masonry walls arching... about 40 years back masonry wall in a local art gallery had arched and the supporting structural slab had deflected nearly 1" and there was a gap (mice could have gone through the opening). The solution was to drypack the space, for appearance only.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[WEJ83]

Okay. Yes, I agree. Our only task at this point is to provide a visual observation and point out areas that may be of concern structurally. If we can't determine a cause with the information available, we'll definitely recommend additional testing of whatever nature is required to pinpoint the problem.

When I began my career, my mentor was a very practical yet brilliant engineer who began practicing in the early 40's. The pre-deflection theory I brought up sounds exactly like something he might have done had he been fighting depth issues or otherwise trying to lighten the steel members. Unfortunately, I don't have him to tap into anymore, so I just thought someone on here might have some historical insight into the issue.

 

[WEJ83]

Just as follow up, found a picture that indicates this has been an issue, or not, for quite some time.

Also, another photo of a very similar courthouse of a couple years later construction, although from a different architect, that seems to have a similar although not quite as pronounced condition.

 

[kipfoot]

Another reference you may have found, built earlier:
[URL unfurl="true"]https://atlas.thc.state.tx.us/NR/pdfs/82004513/82004513.pdf[/url]
How many of these are there? The architect for Lynn County was also the Contractor for Freestone. Tough to tell in the photos, but it also seems to have the same issue.

 

[EcoGen]

[ol 1]
[li]In the photo I see dark rust stains creeping out of the bottom of the thick joint below the brick. It could very likely have been "repaired" by scraping out the existing rust and then packed with mortar. Which means that there may be a lot more corrosion behind this joint.[/li]
[li]Of course it looks like there are no weep holes or flashing which is often the case. So water could definitely be getting stuck behind the brick and corroding the shit out of the lintel. This same phenomenon can be occurring at both locations you mentioned resulting in similar conditions.[/li]
[li]I have seen obvious visible deflection of lintel angles like this before especially when there is a lot of rust buildup. So 2 inches sounds a little excessive but might very well be possible for the 20 foot length. But usually it accompanies some cracking and damage in the brick and mortar joints above also.[/li]
[li]I can't tell from the photo but it looks like at the near end the angle stops short of where it is supposed to be bearing on the remaining brick. Can't really tell without raking out some of the joint at the end. Do you know for sure whether it is a loose lintel bearing on brick on both sides or is it a shelf angle attached to the structure behind it?[/li]
[li]The thick joint below the brick almost looks like it could be soft caulked joint. Are you sure it's a hard mortar joint?[/li]
[/ol]

In either case, the thick joint should be raked out to observe conditions behind the joint. If you find a lot of rust, it's worth remove a couple bricks to investigate further. If it is rust related and there are no weep holes or flashing anywhere, this would be a bitch to eliminate the water causing the rust. I'm involved in project right now where we're removing several courses of brick for the entire length of the building to install new weep holes and flashing. There was a lot of movement and cracking in the brick for that project though so it's different from your case where the brick doesn't seem to be too cracked up.