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A slightly bent stirrup

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  1. #1
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    Default A slightly bent stirrup

    When I refer to post here, I am not referring to timber deck posts but the steel post that forms part of what you buy as a stirrup.

    I was having a look at stirrups in Burnings. There are a few different styles and sizes. The one I was considering buying had a straight tubular post. Yes tubular. I was surprised. I thought they would have been solid steel. There was another design. Same size of stirrup, but the post had a slight bend to it, although the post was shorter. The post on this one was solid steel.

    A few things occur to me. First, I want to weld some extra steel to the post and I fear that these (Pryda) stirrup posts are so thin my weld will hole it. Second, if you want strength in your stirrup why does the manufacturer make the post hollow? Third, there is no way of knowing how far the zinc was applied to the hollow section of the stirrup post. When it's concreted into position, there is no way cement is going to get very far inside the post. There will be an air gap inside the post. It is possible that this hollow post will fill with water in time (concrete is porous), and it may eventually rust from the inside.

    I think I'll buy the solid steel, slightly bent stirrups.

  2. #2
    Resigned SilentButDeadly's Avatar
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    A tube can be stronger that a solid rod of the same size and yet use less material - it is cheaper. Pryda stirrups are hot dip galvanised so they are completely sealed in zinc same as the solid ones. The hollow section is not intended to be filled with cement...

    ...and have a real good think about the likelihood of the tube 'filling up with water' in 'porous' concrete unless the concrete block itself is completely immersed in water.

    Just because you can get your head around some misconceptions doesn't mean the the product is of poor quality...
    Joined RF in 2006...Resigned in 2020.

  3. #3
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    I would trust Pryda over most other steel brands at the green shed.

    Why would the solid ones be bent?

  4. #4
    4K Club Member ringtail's Avatar
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    Just use the high wind type and be done with it.

  5. #5
    4K Club Member Marc's Avatar
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    Default

    What he said, high wind.
    Otherwise, stay clear of those flimsy tube ones I hate them, and use solid stem, they make them different leanghts from 150 to 300 not only short ones, Bunnings does not carry the whole range all the time. It is true that a tube can be as strong as a rod ... sort of ... but the corrosion from the concrete itself will make short work of them.

    If you ever pushed over a veranda with an excavator in order to demolish it and then look at the stirrups, the tube one bend like a banana or snap at concrete level, the solid stem stay straight yet the stirrup weld eventually snaps. The high wind stay straight until the timber snaps and you need a jackhammer to get them out.

    file:///C:/Users/Marc/Downloads/Pryda%2013_Catalogue.pdf
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  6. #6
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    Quote Originally Posted by SilentButDeadly View Post
    A tube can be stronger that a solid rod of the same size and yet use less material
    That actually assumes stuff your not saying. A tube can be stonger, but would have to be larger. Think of the drive shafts on a front wheel drive car. They are solid steel and about 25mm dia. Now consider the drive shaft on a rear wheel drive car. They have a tubular construction and but are about 3-4 times the diameter.


    Quote Originally Posted by SilentButDeadly View Post
    ...and have a real good think about the likelihood of the tube 'filling up with water' in 'porous' concrete unless the concrete block itself is completely immersed in water.
    The thing is, I dug the holes for the footings, 600mm deep. Two days later one of them had about 500mm water in the hole. The holes have been made in a position that are lower than the natural ground level, and any ground water that's nearby, particularly following the rain we've had just turns the holes quickly turn into a well. I suspect these footings are always going to be surrounded by water. I now rust in concrete is unlkely, but given there will be air + water + iron inside that tube, I'm not confident. And there is no way to tell for sure that all the zinc got to where it was meant to me. And as I said I'm going to be doing some welding. That will mean there will be no zinc around the inside of the tube where the weld is.

  7. #7
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    Quote Originally Posted by r3nov8or View Post
    Why would the solid ones be bent?
    Designed that way. Not so much bent but curved/deformed at the base. To keep it from pulling out of the concrete.

  8. #8
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    Quote Originally Posted by ErrolFlynn View Post
    That actually assumes stuff your not saying. A tube can be stonger, but would have to be larger. Think of the drive shafts on a front wheel drive car. They are solid steel and about 25mm dia. Now consider the drive shaft on a rear wheel drive car. They have a tubular construction and but are about 3-4 times the diameter.



    The thing is, I dug the holes for the footings, 600mm deep. Two days later one of them had about 500mm water in the hole. The holes have been made in a position that are lower than the natural ground level, and any ground water that's nearby, particularly following the rain we've had just turns the holes quickly turn into a well. I suspect these footings are always going to be surrounded by water. I now rust in concrete is unlkely, but given there will be air + water + iron inside that tube, I'm not confident. And there is no way to tell for sure that all the zinc got to where it was meant to me. And as I said I'm going to be doing some welding. That will mean there will be no zinc around the inside of the tube where the weld is.
    You need to put in place some retaining walls and or drainage.

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