Steel Beam for Masonry Wall Header / Tie Beam

[patrick p]

We have a small home addition using masonry walls. The front of the garage will get a garage door. The concrete header that was designed (also acts as lintel at the opening) ties the side walls, and is a rather massive concrete beam. Since the slab addition to the front of the house is rather small, minimizing weight on this section seems like a logical thing to do. It seems also simpler to hoist a relatively light weight steel beam than to form and poor a concrete beam.

...So it seems logical to use an I-Beam for the header / lintel / tie beam, located at the top of the masonry wall over the garage door opening. Curious if anybody here has any experience doing this, and if there are any reasons why this would be a flawed approach or specifically prohibited by codes.

 

[KootK]

1) I don't see any insermountable problems with this. In my area, I would say that the steel beam is the more common solution.

2) In addition to the basic spanning function, you may need to consider the ability of your beam bearing connections to transmit axial and uplift forces out of your beam in into to your walls. These things are often easier to accomplish with a concrete/block beam given the inherent integration that you often get between wall and beam with those systems.

 

[J189]

Hi KootK, Since you mention the connection, I have a question for you. Do you use bolts to connect the steel beam to the masonry wall in addition to the bearing plate? I have seen people use bolts to connect the bottom flange to the wall as well as to the end side of the wall using a end plate welded to the beam. What is the consideration of this?

 

[KootK]

Hi J189. I typically do it as you've described, with embedded bolts/studs connecting the masonry (and preferably the rebar) to the bearing plate. Depending on the scale of the thing, I may attempt a rocker inspired connection that limits the transmission of beam end moments into the wall (I hope / wish).

In my experience, simple bolts can usually be made to handle uplift forces quite readdily. Chord/strut forces have presented more of a challenge. As you can imagine, the bolts tend to have lousy edge distances and, therefore, lousy shear breakout capacities. If at all possible, I prefer to have some masonry run over top of the beam that can serve as a continuation of the wall bond beam.

In one instance, I had weldable rebar laid into the block coursing a course above the beam bearing. I then had those bars field welded to the web of the beam to form an axial connection to the wall independent of the bearing plate assembly. I received no complaints about this and verified that it actually came to pass in the field. I'm sure that the construction team thought it was a bit nutty though.

 

[r13]

Although both concrete beam and steel beam will work, with long term performance in mind, I prefer concrete over steel for the reasons: 1) Similar thermal property of brick and concrete. 2) Better bond between brick and concrete. 3) Easier to tie the end walls.

 

[patrick p]

Thank you Kooktk for your input. Indeed the connection details will no doubt require careful attention, and any localized stresses as well.

I'm thinking the easiest approach will be to use a threaded rod to make the bolted connections (vertical), and lap these with the rebar in the columns to achieve that tie in of the steel via concrete, then pour the columns, in such a way to encapsulate the end of the beam... Should work

 

[J189]

Thanks for your reply KootK. If a bolt connection is used, how do you calculate the breakout capacity of the brick/block wall and the pull-out etc? Can the anchorage section in ACI be used here as well?

 

[KootK]

If I'm trying to get the job done with grout breakout capacity alone, I'll attempt to use the provisions built into my masonry code for embedded anchor bolts. That said, I'd be fine with treating it per ACI anchorage provisions as well.

 

[XR250]

Patrick P,

How many feet of masonry is above the beam?

 

[patrick p]

0 It is the 'header'/ lintel of a single story structure. It supports the roof loads, and acts as tie between the two adjacent walls