I need help Please - design of parapet on top of stonework retainig wall 1

[Musheir El-Farra]

I am designing a parapet replacement for a Cast Iron parapet on top of a grade ii listed stonework retaining wall. The new parapet will be mounted on top of the retaining wall. The wall was constructed in 1780; it's not showing any movement but as expected erosion of mortar joints; few cracks; missing section in some areas etc.

How do I design the foundation? do I design it to take 1.5 Kn/m pedistrian load on top of the parapet ( to TD 19 with factors of safety applied) and check it for Overturning and sliding. This will result in concrete foundation pad under every post which will increase the cost as the numbe rof posts are 120.

Would it be an option to consider coring through the stonework wall (To what depth ???) to insert dowels embeded in eposy resin material or concrete grout then connected to the parapet post foundation. I don't know how to design such an option .

Two photos of the existing parapet on top of the wall is below.

Many thanks


.

 

[oldestguy]

Instead of a design, look at replacing the top course, but tie that into the slab with dowels.

 

[PEinc]

Design a moment slab that sits on top of the wall and then mount the parapet on the moment slab. This is commonly done.

http://www.PeirceEngineering.com

 

[r13]

it's not showing any movement but as expected erosion of mortar joints; few cracks; missing section in some areas etc.

If the above is describing the stone wall surface, I think you know how to handle those defects - tuckpoint the weathered joints and replace missing stones. However, for the deterioration of the cast iron handrail post, I don't think you shall do anything before understand how it was set in place.

If the pavement edger is concrete, you can simply replace it with the same. If it is stone header, I suggest to remove a few facing stones beneath to uncover the support detail, and find a way to handle the repair. Please keep in mind, this stone wall and cast iron hand railing system might have historical significance, which shall be preserved. So be prudent in repair and replacement - method and material wise.

 

[bridgebuster]

What PEInc said, done it a bunch of times on old walls in NYC. This is just an example; it was a park road; the barrier only had to be designed for a very light vehicle.

 

[IRstuff]

Are the original parapet's footings insufficient?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[oldestguy]

This old wall likely has significant historical value. Changing it into a modern reinforced concrete top section will likely get local opposition. Comments on how to replace only the deteriorated sections with similar to originals probably would be of some value for the poster. As to checking the strength of the new work, that old one has demonstrated it is fine. So don't fool with that part. Cost also appears to be a factor here, so don't tear out what is not in trouble.

 

[EireChch]

The existing fence looks like its in good shape.

(I cant offer any better suggestions than the guys did above)

 

[bridgebuster]

That's the advantage of the moment; the railing can be upgraded to current standards while leaving the original wall intact. A form liner and stain or colored concrete can be used to replicate the appearance of stone. To fix the wall, it's just a matter of replacing the deteriorated stones with new ones.

Parapets and railings can be trickier, due to legal concerns. In NY, a non-conforming parapet or railing can be repaired but if it's reconstructed then it has to be brought up to current standards. On a project I did a few years back, the parkway (that's a type of road in NYS that's only for non-commercial vehicles)had stone parapets. The owner didn't want to replace a few thousand feet of parapet; so we just did localized repairs.