Glulam Modification/Replacement 3

[Bhotar3]

I’ve been tasked to Analyze and give a Engineering Judgement on a damaged glulam beam for an apartment complex. I wanted to get a feel for potential solutions from the board here, as I don’t have a ton of experience dealing with Timber design.

A truck didn’t clear the bottom of the beam, and At first glimpse, there is pretty significant damage to the structure. It looks like it gouged out a pretty decent chuck of the member. Also, it looks like there has been some significant moisture damage now that the beam is exposed.

Are there any potential retrofit ideas here? Could they potentially bolt metal plates on both sides of the affected portion? I would assume you can not cut out and splice in a new beam just at the damaged location (or maybe you can and just need to design significant splice connections).

Or is a complete replace in kind the only realistic option? It would require substantial bracing, as this complex is 3 stories.

 

[XR250]

What a blessing that the truck hit the beam.
I would figure out your moisture issue and then do wholesale replacement.

 

[BridgeSmith]

Epoxy repair materials could be an option, albeit an expensive one for he volume of material needed. It may require some anchorage pins or dowels to restore structural integrity. It would allow for repair in place, minimizing the required shoring and refinishing work, which overall may present a savings. OTOH, if the rot extends to a significant portion of the beam length, replacement may be the best option.

I agree with XR250, addressing the moisture issue that caused the deterioration is a key component, and that may end up being the more expensive part of the fix.

 

[dik]

penetrating epoxy is often used to repair ship/boat hulls. The damage is extensive and the glulam should be replaced. Not a fault of the truck driver; beam, if loaded, was ready for failure at anytime.

Dik

 

[dhengr]

Bhotar3:
I’ll bet the damage is much deeper and greater in area than the elevation photo shows. I’d look up around the windows above, they are probably not properly flashed and caulked. Look also at that horiz. trim right above the beam. What does the wind and water plane material and detailing look like? That’s fairly frustrating, poor detailing and construction, but also fairly common. The GluLam is not likely salvageable by the time you see the full extent of the damage.

 

[Bhotar3]

When I was initially contacted by the client, it seemed as if the Gouge in the beam was created by the impact of the truck, but it seems as though the real concern is localized (and potentially full) rot of the beam. If that is the case, then I would agree it needs to be replaced.

The architect is wanted a recommendation on if the member needs replacing, and if so, further consultation on the required repair.

So here are a couple of questions for you guys:
1. In the report, I would say "beam shows significant amount of rot and degradation to warrant full replacement. My recommendation is to replace glulam beam in-kind. Contact Licensed Contractor for most efficient Installation/Shoring method. Ensure adequate drip edge to alleviate future moisture exposure"

I'm not a contractor, and wouldn't know where to start with shoring this thing. Does the constructability of replacing this member still fall on my shoulders? If so, I will do my research, or work with a contractor to determine the proper approach.​

2. If this job required, 2.5 hours of travel and inspection, and 2 pages of Engineering report. What would you guys charge the client? (Just recommendation. Not further consultation)

 

[Brad805]

Be very careful on this project. That image suggests an underlying building envelope problem that will involve costly repairs. If they flashed the openings as poorly as that appears to be, I would not be shocked there are a lot more problems. That beam needs to be replaced and I would expect you will uncover much much more damage in doing so. How old is the building?

 

[Bhotar3]

@Brad805 10 years.

I'm not designing anything, so much as I am giving my recommendation of replacement (So far the determination is it should probably be replaced). I also see no issue with replacing it in-kind as it's been adequately supporting for a decade, and continues to support while damaged. The risk, is to say "replace the beam" and not clarifying that more discovery needs to be done to locate the source of moisture. I plan to work with the contractor to determine a source, potentially conduct further inspection of surrounding structure (further rot, flasing, etc. etc.), and discuss best method of replacement. Essentially covering all bases.

 

[Sawbux]

I would be tempted to ditch the wood beam solution and use a steel beam. Might by more time before situation reoccurs.

Is there a similar beam on the other side of the opening? Might have same problem!

Repair will depend on the construction details. Are floor joists framed into back side of beam? or do they sit on top? If on top, it would be easier to shore and replace.

 

[msquared48]

Do not wait to issue your report to recommend shoring. Tell them to do shoring NOW! And followup with the report.

Be prepared to make a shoring plan.

Mike McCann, PE, SE (WA)

 

[msquared48]

I would also consider taking a 1" diameter core at the center of the beam.

Mike McCann, PE, SE (WA)

 

[Brad805]

Ok, that sounds reasonable. This tends to be the type of project where you have a discussion with the architect or owner about your scope, but it may or not be explicitly stated anywhere. If there is ever a problem lawyers claim your scope was not restricted, and it is easy to end up defending yourself for something outside your perceived scope of works. You have been on site, it can easily become your baby. My point is to be verbose and crystal clear.

10yeaars and that level of decay is terrible performance unless you are in a very humid climate. I would suggest preliminary investigation using non-destructive (or minimally destructive) methods for each of the headers in the elevation you have shown. A copy of the original drawings will be helpful to see the typical building envelope details.

I agree with msq. Shoring should be immediate. Fun discussions ahead with that one since this appears to be an important entrance.

This is an hourly assignment. You need to have a frank discussion with the owner to get a sense how they might want to proceed. If they are hesitant about looking into the problems in detail, I would think twice about taking them on as a client. It is still easy to say no. The risk v reward may not be worth it here.

 

[msquared48]

Another point - with 3 inches of width lost in the bottom tension members, the beam is severely overstressed in tension assuming a 6.75 inch width.

Replacement is the only option here in my opinion.

And fix that (those) water leak(s)!!!!!

Mike McCann, PE, SE (WA)

 

[BAretired]

If you are going to replace the beam, consider using exterior grade glulam or steel.

BA

 

[Bhotar3]

I received a copy of the existing floor plan layout. Looks like Parallams were used (if I’m reading this correctly, 2 Parallams side by side?). Anyone familiar with what (C=1”) means? Camber maybe?

If there are 2, definitely need to inspect the 2nd beam that’s not exposed.

@Sawbux, it looks as if the Joists run on top of the beams.

@Brad805: the scope was clearly stated via an email from the architect to my client (who has contacted me)
“Please inspect the damaged beam and ascertain whether or not it requires repair or replacement. If it does, we will need your further consultation regarding any required repair or replacement.”

Step 1: write a report and seal stating findings.

As it stands right now, it looks like it may turn into designing a solution. Which, I’m imagining would start with further discovery.

@Msquared48.
Thanks a lot for your input. Great idea. I haven’t actually gone out to inspect it yet. The pictures I attached were sent to me, but yes, recommending shoring right away is a good idea.
As far as your cores. What are we looking for? Uniform rot through the width of the beam? IMO, more stucco needs to be peeled back here, and a lot more of the structure inspected. Also, leak source identified.

 

[msquared48]

Not knowing the situation, I would like to verify the amount of good wood remaining, not that it matters that much from looking at the picture...

Mike McCann, PE, SE (WA)

 

[Bhotar3]

@Msquared48
Got it. Any idea what the (C=1") is on the plans? Could it be the clear spacing b/w beams? Also, do you interpret it to be two parallams beside each other?

 

[msquared48]

C is for the camber, and, yes, two paralams.

The paralams should be stitch bolted together, but I see no evidence of that in the picture.

Mike McCann, PE, SE (WA)

 

[msquared48]

But glulam(s) were used.. duh!

Mike McCann, PE, SE (WA)

 

[Brad805]

You have building paper and stucco directly over the sheathing. That coupled with poor flashing that does not allow water to escape is the common cause for this. The lack of flashing at the bottom of the beam is an indication of the potential underlying problem here. I would be looking at the flashing above the ledge as well because it appears suspect in the pictures.

I think a simple pick test of the beam will suffice in this case. Cores would be more useful if there was only a minor amount of decay and you want to see if the wood is competent. Here I predict you will be able to pick away the bottom of the outer ply with the claws of a hammer and little effort.

Good luck.