de-sheath i-beam in attached garage? Code?

[Gutman]

I second talking with your local AHJ.

When I lived in NoVA, I had a discussion with a local building inspector regarding a similar situation in my garage, and he explained that often they were boxed with framing and drywall for aesthetics in garages, but the web cavity into the adjoining walls needed to be sealed and the drywall butting up to the I-beam flange needed to be sealed with an appropriate firestop if the beam were to be exposed.

That said, in walking through many homes being built in the late 90s and early 2000s during the building boom, there were many garages I saw that had exposed beams with drywall butted up to the flange, no caulk or sealant, and fiberglass insulation stuffed in the cavities at the ends of the beam.

Now that was probably 15 years ago, but talk to the AHJ and explain what you want to be able to do and what would some acceptable solutions be.

 

[Bill T]

At an in-service seminar on 9/11, for fire inspectors, I heard a presentation about the construction methods used when the TTT was built in the 1970's. It opened 4/4/1973.

There were multiple methods used for providing fire resistance. When the fueled plane impacted the building, the shock wave knocked-loose the steel coatings and drywall, and the ruptured fuels spilled throughout the structure down from the point of impact. The damage to the building destroyed the sprinkler systems, rendering them inoperable. Once the fire spread, the supporting structure weakened and a pancake collapse as we all saw, to our horror, took out the inhabitants and 343 firefighters from FDNY.

One of the issues in construction is that the trades are responsible for restoring the fire-resistive buildings' methods of construction. They may not do that, effectively, and in the absence of vigilant enforcement by the lifesafety inspectors, and the other trades inspectors the building is susceptible to structural failure in the event of a fire.

Francis Brannigan SFPE (the USA has more licensed psychiatrists than fire protection engineers) and Vincent Dunn Deputy Chief FDNY (ret.) have continuously advocated for better fire protection standards and methods of fire-resistant building construction. One of the statistics relevant to potential weakening of a steel structural member is that a 100ft. beam lengthens 9-1/2 inches as it reaches 1,000 degrees F. What happens to the structural integrity of a building under such conditions? If the concrete structure containing steel beams is massive-enough to prevent that amount of expansion of the steel structural member, that will cause the middle of the steel beam to buckle/fail.

Construction Concerns: Expansion of Metals

The expansion of steel beams under fire conditions can cause structural collapse. Gregory Havel reviews devices used to control the expansion of pipes and the effects of expanding structural steel.

www.fireengineering.com

When I entered the fire service nearly 50 years ago, we were taught that steel bar truss construction was capable of withstanding collapse for nearly 10 minutes, but the accumulation of evidence since then has shown that collapse of the structural element can happen in in two minutes or less, given the proper conditions. Data-driven information helps us to understand the changes in the building involved in a structure fire, and to understand how buildings can be made more fire-resistant with advances in building construction and new materials. Occupants are given a better chance of evacuation from an involved building, and firefighters a better chance to protect lives, reducing morbidity and mortality, and hopefully being able to stop the spread of fire, and to extinguish the conflagration while stopping the spread to other occupancies.

Here is a synopsis of issues raised in a forensic review of the TTT disaster.

https://jnocook.net/texts/wtcfire.htm

I am a retired firefighter/paramedic, lifesafety inspector, and FL licensed fire service instructor III, and hold other qualifications.

Thank you for the "Informed" reply. This the true value of forums. While there may be 10 "jack-leg" replies for every one informed reply, the one good reply makes sifting through the chaf worthwhile.

 

[75gmck25]

Years ago I bought a book that explained the TTT construction and how the design led to the building falling so quickly. Based on what I remember, these were key points:
- It was build to withstand impact from an airliner, but not designed to survive a massive fire like 9/11. Based on historical data, the primary risk was assumed to be physical impact by an airplane.
- Beam size, fire coatings building design and other factors were based on a design that allowed them to use lighter and lighter components on subsequent floors as the building got higher. This was considered to be a sound design.
- The fire stairs on each corner were part of the design, and they worked with the rest of the building to support the structural integrity. When one plane hit the corner it had a massive impact on overall structural integrity.
- Once again, the design did not allow for a massive, hot fire created by burning jet fuel. The fire was so hot that it burned off fire-proof coatings, caused beams to shift, sag and fail, etc.

 

[billconner]

Years ago I bought a book that explained the TTT construction and how the design led to the building falling so quickly. Based on what I remember, these were key points:
- It was build to withstand impact from an airliner, but not designed to survive a massive fire like 9/11. Based on historical data, the primary risk was assumed to be physical impact by an airplane.
- Beam size, fire coatings building design and other factors were based on a design that allowed them to use lighter and lighter components on subsequent floors as the building got higher. This was considered to be a sound design.
- The fire stairs on each corner were part of the design, and they worked with the rest of the building to support the structural integrity. When one plane hit the corner it had a massive impact on overall structural integrity.
- Once again, the design did not allow for a massive, hot fire created by burning jet fuel. The fire was so hot that it burned off fire-proof coatings, caused beams to shift, sag and fail, etc.

Good post but not quite relevant to garage. Iirc, designed for a smaller airplane than what struck it. Also it's was somewhat new to do the stair towers out of steel studs and drywall, rather than masonry, which probably would have lasted longer.

 

[driftpin]

In response to comments on WTC/TTT, on fire-rescue here in FL, I worked with a retired FDNY firefighter, who was also a FDNY fire inspector. He lost a lot of people he knew personally on September 11. Whenever he and I spoke about WTC and I called them "the Twin Trade Towers" or "the TTT," he never asked me, "what is that?" The two terms WTC/TTT were used interchangeably at multiple fire service seminars I attended. I have used either term (WTC/TTT) and whichever term one uses, I will understand them. Others who are not familiar with the alternative, of course it was not my intent to confuse any GJ readers.

I got up early on September 11, 2001, and I attended early Mass at the Catholic Church closest to where I was working. A friend of mine had died, and the Mass was offered for her and for others. Little did I expect that such a tragedy would happen, changing how we live.

Here is another paper by FDNY Deputy Chief Vincent Dunn (ret.) about NYC building construction, FDNY radio communications, and other cities' methods of building construction.

"Why the World Trade Center Buildings Collapsed", by Deputy Chief Vincent Dunn, FDNY Retired