Torsion on LVL beam supporting brick 2

[structurebeton]

I recently did an inspection on an 18 ft span beam lintel, most likely made of an LVL beam (Drywall is still in place). The beam is supporting half of a 2nd story, roof and brick. The brick is supported on a steel angle which in turn is bolted to the LVL beam. The beam is currently at a deflection of L/300 and the brick facade has cracked. There is also slight twist of the steel angle.

The questions are:
1) Is it allowed by code to support brick with a Pre-engineered wood beam? (Despite the fact that the criteria of L/600 deflection is respected). I could not locate on IBC2006 were this is addressed.

2) Do you have a good reference on calculating strength of a wood beam due to excentric loading, such as brick?

3) In repairing the beam, should we simply replace the wood with a steel tube beam, which then would require steel columns...

Any comments would be appreciated. Thanks,

ST

 

[hokie66]

Mike's proposal to retrofit kickers would work structurally, but the overhead door is in the way. I doubt you could get the kickers low enough on the beam to do much good.

I suppose installing a new column in the middle of the opening is out of the question?

 

[structurebeton]

Installing a column in the middle is absolutely out of the question. This is a 650k house. In fact, I am wondering if it would be even possible to replace altogether the existing beam for a new one. That certainly would involve some serious shoring...

 

[IceNine]

JAE-

The IRC also states that veneer above openings shall be supported by non-combustible materials (R703.7.3)

 

[WillisV]

As a semi-related point, the new version of ACI-530 got rid of that pesky 0.3" limit - its only L/600 now.

 

[msquared48]

It looks like there could possibly be a large point load from the roof - maybe a girder truss if it is a trussed roof - at the center of the garage door header span. Is the roof trussed, stick framed, or a mix? The effect of any girder truss or point load may have been omitted on the header, especially if this structure did not have an original engineer involved in the design.

It is also interesting to note that a valley frames into the center of the span too. Was this a sudden condition or gradual? If sudden, was there a heavy snow that loaded the valley.

With that amount of brick above, the owner better seriously consider adding a central column to remedy the situation. Should they ever try to sell the place with out a fix, they are going to take a much bigger hit if it is not fixed than nessing up the exterior look. FUNCTION BEFORE FORM HERE - FOR SAFETY.

There were two 6.8 or higher earthquakes on the Western portion of the Pacific rim yesterday. A 7.2 off the Kuril Islands, and a 6.8 near New Caledonia. Is this structure in a high earthquake zone?

Mike McCann
MMC Engineering

 

[structurebeton]

The structure is located in Georgia, so no snow to worry about. The condition most likely appeared gradually over approximately 3 years, as the crack were patched at first when the owner bought the house, and it seems cracks have reappeared after 3 years. We are in the process of having a contractor do an estimate of fixing the condition since this is in the middle of a buying inspection process.

The contractor will probably provide a high estimate since, as I told him, there is no engineering design done yet.

 

[msquared48]

OK.

Then also check the end bearing on the header to the columns. If this is a gradual condition, it could be crushing the bottom of the beam, causing the gradual cracking. Torsional stresses may be the least of your problems here.

Mike McCann
MMC Engineering

 

[JAE]

IceNine,

Yes - that's why you use a steel angle and ensure that there is a moisture barrier/separation between the exterior and wood beam - per LobstaEata's post (8th from the top).

 

[bigmig]

structurebeton,

Find out what the beam actually is before you go to the effort of thinking about replacing it. Drywall patching = cheap. You and the other people spinning their wheels speculating = expensive. When you find out the beam overstresses post that....also find out how the angle is connected (lags or thru-bolts?)

 

[IceNine]

JAE-

The LVL is part of the lintel, and the code specifically calls for veneer above openings to be supported by non combustible lintels.

 

[JAE]

IceNine,

I believe you are correct...I stand corrected. Thanks.

 

[structurebeton]

So, it is then necessary to use a steel beam??? Then also use steel columns? That seems a bit extreme...Are you sure about that restriction?

 

[LobstaEata]

IceNine

Take a look at Figure R703.7.2.2 above, showing masonry veneer being supported on a steel angle and fastened to wood studs. The language contained in 703.7.3 (or at least a strict interpretation) seems to directly conflict with the associated figure on teh same page. It would be interesting to contact someone at the ICC to obtain a clarification.

 

[bigmig]

This is an interesting thread that seems to be coming down to the other question of which code do you use (IBC or IRC). Keep in mind that steel design is not part of the IRC, so would you then be jumping to the IRC if you introduced steel...?? The provisions of the IBC Section 2304.12 are pretty clear about wood members supporting veneer.

I went to a introduction of the 2003 IBC/IRC back in the day and the code official explained that if "it" doesn't fit in the IRC, then use the IBC. I'd say that masonry veneer on a steel lintel fit better with the IBC. In which case I'd go with the Section 2304.12 which says wood supporting 4" veneer is a go.

 

[bigmig]

Sorry, I had a typ-o in my previous statement which should have read..."..jumping to the IBC...". Sorry for any confusion.

 

[msquared48]

I believe that if you have a minimum nominal 6X beam, it is a one hour fire rating without being wrapped. If the studs shown in the detail mentioned above are wrapped with 1/2" gyp, then that is 1 hour too. I do not really see the problem with the language and the detail in the field actual application here.

Mike McCann
MMC Engineering

 

[structurebeton]

I would think that either IBC or IRC apply, up to the engineer's judgement, to a residential house.

 

[IceNine]

bigmig-

2304.12 allows brick veneer to be supported by a wood foundation.

2104.1.6 rules out other uses, including lintels

 

[structurebeton]

So, are you all telling that it is necessary to use a steel beam to support a 18 ft span on a residential house, because there is brick veneer?

Any conclusions on this?

 

[JLNJ]

If it's done moving maybe you just live with it.

If it's NOT done moving (i.e. a foundation issue) then you might spend $$ to fix with a nice heavy sttel beam only to have the crack open up all over again!