Steeple Spire

[SteveMort]

During an inspection of the interior of a church steeple spire, we noticed that there were masonry pockets built into the brick walls. Some of the pockets still had wood members in them but the rest of the wood members were water damaged and termite damaged and had fallen to the floor below. The pockets are located such that the wood members were installed across four of the eight walls (only the walls with windows) and are located every five feet vertically. Does anyone know the purpose of the wood members? If they are braces, I would recommend replacing them. If they were maybe used as staging to build the spire, they do not need to be replaced. Any ideas? The spire is brick on the interior and stone on the exterior. It rises about 40 feet.

 

[JStructsteel]

If they are just on one face like that, I certainly dont see them as braces, as the other 6 corners are unbranded correct?

Could have been a formwork of sorts to built it.

 

[KootK]

I agree, it's hard to imagine those wood members doing anything meaningful structurally. Maybe there was, at one time, some kind of non-OSHA approved scaffolding system intended to allow access to the windows? That's just a wild guess. Something to do with the construction process seems much more plausible.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JStephen]

Sounds like scaffolding or construction bracing to me.

So...back when this was built, was there any kind of design that would have been done that would have demonstrated the need for bracing? Or did some architect say "Let's make it about yay-thick" and that was it?

If it was bracing, you'd need it at the wider part, not so much in the skinnier part. If it was scaffolding, you'd need it all the way up.

 

[KootK]

Is there any evidence to suggest that there might have been wood members crossing the steeple from one wood "brace" member to the wood members on the opposing walls?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dhengr]

SteveMort:
As JStephen suggests, bracing would more likely be needed down near the max. circumference and I would expect any bracing to show some tension strength and connection, not just compressive strength. Or, as KootK suggests, some cross bracing at any level to make it something of a rigid frame or a diaphragm. At the spring line of that steeple, there will be some thrust component which should be reacted by a floor framing system or something, maybe a tension ring. If those pockets and wooden members are at a uniform vert. spacing, and a consistent orientation, my vote would be for construction bracing and staging, as the thing was build. Then they just left them there for future use. I think I’ve seen schemes like this used for building large masonry chimneys. They would pocket in some beams and build a working floor with some planks. Then they could store building materials at a convenient location and use scaffolding for a couple stories in height. Then they would build another working fl. and jump the scaffolding up. They would take all this apart and fill the pockets as they worked their way back down on a chimney.