Long steel beam for residential deck standard practice 3

[DoubleStud]

What is the standard practice if I have a series of straight steel beam (5 columns, 4 spans) that is 50 ft total? This will be supporting a high end concrete deck with heating tube. Do I design the beams as continuous and put a connection at the inflection point? Do I design the beam as single spans and put a connection somewhere just next to the middle column? Other way? This steel beam will be visible. I don't think they want a 50 ft long beam. Typically the decks I design are not this long. If I use steel, typically I have been specifying continuous beam. Maybe I just specify the steel beams to connect to the side of the steel columns? That way I have 4 short pieces? What would you do?

 

[Eng16080]

For the deck to house connection, I always use at least 2 hold down connections anchored into the floor framing. Decks scare me. I usually design them so that if the deck were to fall off the building it has to tear out the floor of the house with it! I would assume the joist to ledger connection has no withdrawal/tension capacity if it will be exposed to moisture. In 20 years, there’s a good chance the ledger is rotted and the fasteners are compromised.

Actually, making the deck freestanding is usually my preference especially for ones which aren’t too high off the ground.

Also, I would be careful mixing all these different materials in terms of moisture resistance and rot/corrosion. Be careful that there isn’t a corrosion risk due to dissimilar material contact. Definitely use galvanized or stainless steel for the beams and columns. I would also entertain using steel instead of PT joists, but maybe this is a problem aesthetically.

 

[Eng16080]

Ok, I should have maybe looked at the detail before responding. Considering that the deck framing is concealed, I would probably use a steel system with metal deck, all galvanized. Not sure how to get the pitch for runoff. Can the concrete be poured thicker near the wall? Should be possible I think.

 

[XR250]

Definitely use galvanized or stainless steel for the beams and columns. I would also entertain using steel instead of PT joists, but maybe this is a problem aesthetical

Stainless steel beams and columns - really?
Since the beam and columns are mostly protected by the deck, I would entertain painting.
I see many 50 year old decks around here with painted beams and columns still functioning.
Also, I am going to put this out there again - I would never consider making the decision of cont. versus segmented beams without asking the Arch and/or Contractor what their preference is. I don't like having to re-design things at an inopportune time when they decide they don't like your choice.

 

[gte447f]

XR250, totally agree on stainless steel beams and columns... huh?!? For exterior use they should be galvanized in my opinion, but asking for galvanized in the residential market that I am used to is probably wishful thinking. Paint and decent regular maintenance can last a long time.

Can't agree on getting architect or contractor input on continuous vs simple span beams though. It would be a rare exception for me to care about either's opinion, mainly because I would expect them both to be completely clueless. I would expect most architects to draw a section showing a continuous beam over the columns only because they think this is how all beams are supported. In most cases I would explain that simple spans and shear tabs are more appropriate, and I would ask if there was any particular reason why they had drawn the section showing a continuous beam. The contractor's opinion would never enter my mind. Sorry if that sounds bull headed. Maybe your residential projects are more professionally deigned and constructed than the ones I have been involved with.

 

[XR250]

Can't agree on getting architect or contractor input on continuous vs simple span beams though. It would be a rare exception for me to care about either's opinion, mainly because I would expect them both to be completely clueless

I have a contractor client who always wants continuous steel. He has a crane easily available and likes the way it looks and is just easier for him. I have another who wants simple spans so he does not have to use a crane if possible. Many Arch's I work with like the look of a cont. beam - others don't care.
So I usually ask. These little things add up over the long haul and it is what keeps customers coming back.

 

[gte447f]

XR250, sounds like you have better clients than I do... hahaha... maybe I'll get there someday.

 

[Eng16080]

For exterior steel exposed to the elements I usually use galvanized, or try to at least. I would tell the client up front. If I got push back, I would probably be ok with primed and painted steel and in that case I would probably select a section with thicker flanges and web accounting for a reduced section due to rusting. We all know that periodic maintenance/painting likely won’t happen.