Fireproofing of steel tube columns?

[JPohling]

Project is a steel framed mezzanine within a double height suite on the ground floor of a Type I-A building.

Primary structural elements are 3 hours and floor is 2 hours. Client of course wants it to look like the beautiful rendering that the designer made showing essentially exposed steel profiles.

The support columns are 3.5 x 3.5 x 1/4" and i am exploring fireproofing options.

Intumescent fireproofing looks the best but cost is very high.

cementitious fireproofing needs to be nearly 3" thick for this member size and thickness. then wrapped in something to make it look acceptable. gyp, or break metal. columns get to large and clunky.

We have seen some discussion of concrete filled tube steel columns but nothing that seems like it is tested and approved? anyone have any experience with this?

Straight gyp wrap looks like 5 layers of 5/8" gyp to achieve 3 hours on this post. to bulky again.

Anyone have any other suggestions how to minimize the size of the post once protected?

My recommendation of heavy timber falls on deaf ears.

 

[mtlogcabin]

Interesting read on page 20 suggesting concrete filled or water filled may offer additional time before failure
http://www.construccionenacero.com/...re_resistance_of_structural_steel_framing.pdf

Thinking out of the box maybe a water curtain designed for the columns might be acceptable to the AHJ under alternate materials and design. After all the intent is to keep the heat away from the columns so they will not loose structural strength during a fire.

In reality the Intumescent fireproofing looks the best

 

[sergoodo]

Project is a steel framed mezzanine within a double height suite on the ground floor of a Type I-A building.

Primary structural elements are 3 hours and floor is 2 hours. Client of course wants it to look like the beautiful rendering that the designer made showing essentially exposed steel profiles.

The support columns are 3.5 x 3.5 x 1/4" and i am exploring fireproofing options.

Intumescent fireproofing looks the best but cost is very high.

cementitious fireproofing needs to be nearly 3" thick for this member size and thickness. then wrapped in something to make it look acceptable. gyp, or break metal. columns get to large and clunky.

We have seen some discussion of concrete filled tube steel columns but nothing that seems like it is tested and approved? anyone have any experience with this?

Straight gyp wrap looks like 5 layers of 5/8" gyp to achieve 3 hours on this post. to bulky again.

Anyone have any other suggestions how to minimize the size of the post once protected?

My recommendation of heavy timber falls on deaf ears.

Mezzanine is not a story, not building area, only counts as fire area. What is code reference for required ratings? I only see the possibility of sprinklers required.

 

[Mark K]

Intumescent paint does not look as clear an a bare steel column or one with more conventional paint.

There are ratings for concrete filled tubular columns. The designer should contact the steel tube institute. You can get up to a 3 hour rating. This may require a somewhat larger tube to compensate for loss of capacity due to the temperature of the fire.

This essentially what a lally column is. This is very mature technology and has been used for over 40 years.

There are way, in the code, to calculate equivalent fire rating for a bare tube. You end up increasing the size of the tube but if this works you do not need concrete filling.

 

[JPohling]

Mezzanine is not a story, not building area, only counts as fire area. What is code reference for required ratings? I only see the possibility of sprinklers required.

The Type I-A building is fully sprinklered. The mezzanine structure supports an office floor area occupied by employees. Primary and secondary structural elements in a Type I-A building require fire protection. The floor requires fire protection. I have not seen anywhere in the code an exception for fire protection of the structural elements of any mezzanine.

 

[sergoodo]

The Type I-A building is fully sprinklered. The mezzanine structure supports an office floor area occupied by employees. Primary and secondary structural elements in a Type I-A building require fire protection. The floor requires fire protection. I have not seen anywhere in the code an exception for fire protection of the structural elements of any mezzanine.

I just read it as requirements applied to structural elements of a building. We cannot apply all requirements throughout the code for a building consistently to a mezzanine. If this was a 8'x8'' mezzanine set up to view and collect employee efficiency data the application of rated floor and column building requirements would be unreasonable and not make it safer.

 

[JPohling]

I just read it as requirements applied to structural elements of a building. We cannot apply all requirements throughout the code for a building consistently to a mezzanine. If this was a 8'x8'' mezzanine set up to view and collect employee efficiency data the application of rated floor and column building requirements would be unreasonable and not make it safer.

You do not have to apply all of the code requirements to a mezzanine, but you absolutely need to match the construction type and fire ratings of the base building construction type. I am just looking for fireproofing options