Identifying metal object attached to a bridge

[py_megapixel]

A friend sent me these photos of something he'd seen attached to a railway bridge in Leeds and was wondering if I could identify it:

(image shows a metal object attached to a brick wall. It appears to consist of a circular plate with a long, thin protrusion from slightly below the centre. It perhaps vaguely resembles some sort of coat hook, albeit larger.)

The markings near the top are embossed text, which reads "1991 DUCTILE 12M30 S A P"

Does anyone happen to know what this is?

 

[Alpine Rider]

That is a bridge tie. The plate you can see is attached to the end of a metal rod passing through the structure(usually with a similar bridge tie at the far side of the structure. These are normally only installed after construction and intended to correct/stop any subsequently observed bulging/movement of a brick structure.

 

[LondonExile]

Looks to me like a tie bar or tie rod for structural support.

If that is the case, there should be a similar plate on the other side, and they're held together by nuts on a threaded rod running through the structure.

 

[pdeaves]

Similar things, in the form of an 'X' rather than a circle, are often visible on old buildings. They fulfil the same function.

 

[swt_passenger]

I wonder why the tie rod position is not centralised? Maybe there’s a technical reason.

I remember I noticed on one of the EWR project’s existing bridge drawings these type of fittings were labelled as “pattress plates”

 

[Royston Vasey]

I wonder why the tie rod position is not centralised? Maybe there’s a technical reason.

I remember I noticed on one of the EWR project’s existing bridge drawings these type of fittings were labelled as “pattress plates”

I don't know about the process of attaching these but think I can work it out from what I know about metallurgy and explain the lack of centralisation...

By the ductile marking and the unevenness of the plate, and the lack of any obvious nut or fixing, I believe that the plate has been beaten onto the rod, which has pierced it (like receipts on a nail) and it's been hammered on into place flush against the brick. The off centre positioning I guess would have been a result of the worker positioning it there when the force was first applied.

Ductile steel is work hardening, and I assume that the cold work of beating the steel into place, increasing its strength and reducing its ductility, has hardened it and effectively set it in place. Ingenious if so.

I'm probably completely wrong

 

[341o2]

Similar things, in the form of an 'X' rather than a circle, are often visible on old buildings. They fulfil the same function.

Like https://www.thegiddings.org.uk/giddingshtmlfiles/ordinarypages/ordinarywallbraces.html

A feature of some older properties in and around the village are the iron wall ties. These large metal plates are the visible feature of tie rods that pass through the property. There purpose is to hold the exterior wall from bowing out, a problem of two storey houses built on minimal foundations or on an slope of unstable ground. Older farm building also have these feature, although more rudimentary. The plates stop further movement they are not really meant to pull walls back into line.

As can be seen at many other locations. Recently, a terraced house collapsed in Portsmouth, inferior bricks used for the foundations have been blamed

 

[swt_passenger]

I don't know about the process of attaching these but think I can work it out from what I know about metallurgy and explain the lack of centralisation...

By the ductile marking and the unevenness of the plate, and the lack of any obvious nut or fixing, I believe that the plate has been beaten onto the rod, which has pierced it (like receipts on a nail) and it's been hammered on into place flush against the brick. The off centre positioning I guess would have been a result of the worker positioning it there when the force was first applied.

Ductile steel is work hardening, and I assume that the cold work of beating the steel into place, increasing its strength and reducing its ductility, has hardened it and effectively set it in place. Ingenious if so.

I'm probably completely wrong

Ah, I was intrigued about this and I looked up a few manufacturer‘s drawings, there’s a possible explanation here:

Bearing Plates

Wide range of bearing plates as used in rail and construction sectors. Designed for use in areas such as bridge masonry, tradition brick arches and building

www.grip-bar.com

If you scroll down to the first line diagram on the right hand side of the page, it shows a way of using a spherical bush to alter the angle of the tie rod. So a plate with that feature would have an offset shape to the conical part, with the tie rod not being central if fitted ‘plumb’.

So the example shown earlier could be rotated on the rod and used when the walls of the structure were sloping or angled and not parallel with one another.

 

[contrex]

Similar things, in the form of an 'X' rather than a circle, are often visible on old buildings. They fulfil the same function.

I remember in a school science lesson being taught about expansion of metals. The teacher said that bulging brickwork used to be corrected by passing an iron rod through a building, emerging at each end through a hole in the wall. The rod was threaded at each end. It was heated, often using gas burners, and at a suitable temperature, the crosses were tightened down with a nut. The rod was allowed to cool down, and in contracting/shortening back to room temperature, pulled the brick walls back. Finally the rod was cut at each end and removed, but the crosses were often left. I wonder (1) if this is accurate, and (2) if the rods used in the bridges illustrated were left? I can imagine that the rod in a bridge could be shortened by mechanical means like an Acroprop?