Concrete Beam Reinforcement for Large SGD Installation 1

csagan33 · Mar 13, 2025

Hello Everyone,

I have a single-story residential project in which we intend to remove a centrally located concrete column supporting a beam. The goal is to install a large sliding glass door. Upon removing the column, the existing beam exhibits signs of failure in both the top and bottom reinforcement. As I am relatively new to projects of this nature, I am seeking guidance on potential reinforcement solutions.

Specifically, I am considering reinforcing the concrete beam with lateral steel plates, creating a sandwich-type configuration, secured with through bolts. Would this be a viable option? If so, could someone provide insight into the calculation methodology for this type of reinforcement?

Thank you

JAE · Mar 15, 2025

You could use plates - or steel channels - on each side and bolted through to carry the total load - ignoring the concrete beam.
Plates are difficult to design as stand-alone "beams" so I tend towards using channels.

ANE91 · Mar 15, 2025

If your beam is failing, then the opening is likely no longer square enough for the door installation. Consider jacking the beam back to level before strengthening with FRP or steel. This approach allows you to load the repair.

csagan33 · Mar 17, 2025

JAE said:
You could use plates - or steel channels - on each side and bolted through to carry the total load - ignoring the concrete beam.
Plates are difficult to design as stand-alone "beams" so I tend towards using channels.

Good Morning JAE,

I appreciate your feedback, thank you for your guidance. I've been reviewing papers on concrete beams with bolted side plates (BSPs). However, if reinforcing with steel channels is easier to calculate, I'll definitely look into it. I'm attaching a sketch I found to see if this is the way you're suggesting. If so, would they be calculated as independent steel beams considering the live, dead, lateral, and uplift loads that would be considered for the concrete beam, correct? Would the interaction be only with the beam or should there be a connection to the column?"

csagan33 · Mar 17, 2025

ANE91 said:
If your beam is failing, then the opening is likely no longer square enough for the door installation. Consider jacking the beam back to level before strengthening with FRP or steel. This approach allows you to load the repair.

Thank you!, that's a key point.

JAE · Mar 17, 2025

Yes your sketch is roughly what I suggested. The channels look a little small in your sketch compared to the depth of the concrete beam.

For conservatism sake I just design the channels to take all the load.
Whether they need to be affixed to the beam ends with added anchors (to take out all the channel shear into the concrete beam) - or whether to extend to the column, or new support columns would depend on the situation at the ends. I can't answer that for you other than to say the end shear reactions have to go somewhere so you need to follow them through with a proper design.

csagan33 · Mar 18, 2025

Following your suggestion, I've completed a preliminary design, including C-channel calculations for load demands and connections to the existing beam. However, removing the center column results in a 16.8 ft span with 14.4 kip reactions. I'm now focusing on the connection to existing grout-filled CMU columns.

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Concrete Beam Reinforcement for Large SGD Installation 1

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