existing structure - what to do here? 1

[greznik91]

Very old existing structure - wide stone walls, timber roof

The conctractor made a steel column (part of steel frame that supports new roof) above existing window opening (span of 1,30 m). There is no real lintel - just stone and some mortar that acts as lintel. Column is supported on existing timber ceiling. Timber beam shown in attached image is only 100 x 100 mm and is not a bearing element.

What is the best solution here? How to strenghten/reinforce existing lintel? I was thinkin to replace timber beam with some steel but That might be risky since there is a timber ceiling and a steel column directly above.

 

[EngEstrutural]

First, shore the structure if it's failing.

The contractor can't do something without the supervision of an engineer signing responsibility for the work, talk to this engineer and show his neck is on the line.

If there is no engineer, you'll need to redesign the strucutre, NOT THE LINTEL, THE STRUCTURE, because adding an extra floor increases the load considerably in all floors, and also in the foundation.

 

[Enable]

Wait, is this something already in service or is this a proposed design? If it is in service then I agree with EngEstrutural that shoring should be implemented expediently. It's not your mess but you don't want to get caught in the middle of it should something happen. Because as it stands it is your stamp on the line and they messed up; do the smart thing and send a letter demanding shoring to grade ASAP.

Now, if this is a proposal or you've shored things up we can talk load paths. I am not a fan of epoxy anchorage into old stone or masonry generally. I have seen many failures due to the degradation of the internal masonry. That said, you could size a beefy steel lintel with anchorage tiebacks extending from the inside to very near the outside of the masonry wall. You'll want stiffeners. I would 100% proof test these anchors. No way I would trust them without a load test. You can't...it's old masonry what's the capacity?

I don't love the above due to the eccentricity. Seems like that point load is a ways off the corbel and rotation of steel lintels is a tricky thing. I would investigate erecting a beam underneath the point loads that spans from the nearest bearing walls. If that is architecturally unpalatable OR finishes are an issue they can install this beam ABOVE on the old roof level just underneath the steel posts they plan to erect. They would need to cut them/slide in the new beam that spans from wall to wall and connect the columns to the beam (welding is probably best given the fit issues due to in-situ cutting).

 

[MIStructE_IRE]

Lintel aside, I’d be concerned about the impact on the floor. That’s quite a shear force there too!

Is this existing or proposed??

 

[greznik91]

It's an existing thing. The contractor installed steel column directly on the ceiling instead of a bearing wall. Shear is a concern, but existing ceiling is 200 mm thick timber beams with no spacing between them. The only way I think this can be reinforced somehow is by a steel lintel/beam. I'd like to remove timber beam bellow the ceiling and put a strong steel there but I wonder if this is doable...

 

[MIStructE_IRE]

Wait... isn’t this the concrete topped timber thing we discussed last week?

Looks like your contractor has now introduced punching shear into the mix too.

Personally I’d want a beam under that column.