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This may be a stupid question but how are bearers restrained from sliding on brick piers? I am going to install a floor on piers and I never thought about it until my wife asked the question. I thought it was just friction but I want to make sure. Also what happens when ant caps are involved?
Usually a rod/bolt or a bit of strap. The rod can be laid in the brickwork - you can weld a bit of flat on the bottom and then bring it up through the centre of the pier. It perforates the ant cap, so you need to seal it with no more solder or something termite proof. You can either bend it around the bearer or drill a hole, poke it through and bend it over in the case of rod, or run it through the bearer and use a washer and nut.
There are commercially made steel piers and concrete stumps that include tie-down provisions. Lysaght uni-piers have an integrated ant cap with a bracket to bolt to the bearer. Concrete stumps usually have a bit of rod - they don't need an ant cap. Very popular in Victoria, not so common in NSW. Duragal piers have a number of bracket fittings at the top. They don't need pier caps either.
I would have thought that that should be covered in engineering since you automatically qualify for a builders licence once you have an engineering degree.
When I did the Builders Certificate they taught us how to design suspended/cantilevered slabs, trusses, overhanging traffic light support poles with torsional considerations, steel beams with cantilevers and offset point loads and all sorts of stuff that we'd never be allowed to certify ourselves.
The reasoning being that we'd have an understanding of the subject, and we'd be able to spot any glaring errors in a design.
Nice to have the knowledge, but most of the details have been forgotten and I'd have to drag out my old text books and tables for a refresher if I wanted to waste my time.
thats interesting.Quote:
Originally Posted by silentC
Good news for us pest managers though.
More work for us!
Oops, I was thinking ahead about the Duragal piers. Yes I think that concrete stumps still need pier caps.
The reason the Duragal piers don't is because they have a threaded rod at the top which is the only point of contact between the pier itself and the mounting bracket, so termites would have to track over the threaded rod and would be visible.
Someone can correct me if i'm wrong - the track record hasn't been good lately - but from memory the fixing of bearers to the outer piers [ in a b.v. or solid brick] is only related to 'tie down' which is determined by the wind catagory.
i.e. in a N1 or N2 catagory the bearer simply 'sits' on the pier with no fixing. As you increase into cyclone ratings the tie down becomes stronger to resist uplift and sheer forces. Input into the calculations includes the roof type & the timber type.
Peter is right, brick veneer requires no fixing, the external bearers just sit on the pier, I assume the brick ties assist in tying down the building. Not sure about cyclone areas though, generally internally brick piers will have a strap of hoop iron, not sure if this is a requirement as i have never looked it up as the are always there ( or a steel rood).
Concrete stumps do not need ant caps as ant caps are just there to force the termite galleries to be visible. this is in the termite code AS 3660.1
There's only one house I know of locally that is on concrete stumps - the builder is from Victoria. I'll have to ask him if the local council made him use ant caps.
NSW Framing manual says "all bearers shall be be fixed to each support with nominal fixings given in Clause and Table 2.5 and Figure 8.4".
Table 2.5 says "Bearer to Masonry Column/Wall/Pier for Clad Frame construction (excluding masonry construction): 1/M10 bolt or 1/50 x 4 mm M.S. bar fixed to bearer with M10 bolt and cast into footing. OR One 6mm diameter rod cast into footing positioned vertically through bearer and bent over"
There are obviously no details for masonry construction. I'm not sure whether anything is required for brick veneer. The framing manual is a bit limited in application.
Table 9.3 of simplified AS 1684 says no requirement for fixing bearer to suppoert in masonary veneer construction.
here is a detail fleshing out what silentC said... :aro-u:
this is from 1684.2-2006 (recent residential timber framing code)
the numbers are kN of hold-down force - 1kN is 100kg under gravity (ie imagine that you are standing ontop of the bearer & a someone tries to push up from underneath);
this is what is required if nominal fixing is insufficient (ie, bearer resting on pier); sideways resistance (ie, stopping lateral movement) when only using nominal fixing will be provided by other parts of the substructure - joists, flooring, walls, etcet.
r's brynk
I am not a builder. I can design a lot of structures and civil works but best building practice for how to stop a bearer sliding is not covered. I can design something but I wanted to know what the most common and easiest method would be. And when you say you were taught to design, is that design from first principles? Can you calculate the moments, shears, axial forces and deflections?Quote:
Originally Posted by pawnhead
My piers are internal and thus will have no wind load. So I have just checked AS1684 and found that the nominal fixing 'NO REQUIREMENT'. I will come up with a better solution. I will probably use an angle with a dynabolt and a bolt through the bearer because I think getting the bricklayer to cast in a steel rod will be to hard to organise. The other solution is use some hoop strap and masonry nails.Quote:
Originally Posted by brynk
In the framing manual, tie down is specified for all internal piers. The bearers are tied to the piers, the joists are tied to the bearers, the walls are tied to the joists and the trusses are tied to the walls. If you miss out any of those, it seems pointless to have tie down at all.
Any decent bricky should have done thousands of them. From what I've seen, the rod through the pier is the most common method. You want something that is going to be solid and I don't think dynabolting a bracket to a single brick at the top of the pier is going to satisfy that.
Maybe you should consider using steel piers? The Duragal or Uni pier systems satisfy the tie down requirements. You wont need a bricky at all then.
Why not use concrete stumps ? no one uses brick piers in vic unless they need to suppoert a steel beam or its a high subfloor.
Because the freight from Melbourne to Sydney would be a killer :wink:
You've sort of lost me a bit there, but I recall all of that stuff being discussed, and looking it up in my tables. It was about twenty five years ago now though.Quote:
Originally Posted by DvdHntr
They taught us how to design trusses and calculate all the compression and tension values at each connection.
They taught us how to calculate all the tension stresses (and shear I think) in a suspended and cantilevered concrete slab.
They taught us how to calculate all the shear and tension stresses in a steel beam with point loads at random places along the beam, and they taught us how to design it by using the values that we got, against tables for the properties of steel sections. They also went into steel columns as well. I've still got the book with all the tables of the properties of steel sections somewhere.
And they taught us how to design a steel structure supporting an overhead set of traffic lights, ie a column that's bolted to a footing on the footpath, extending up, with a beam bolted on top that goes out over the roadway supporting the traffic lights. We had to calculate the torsional forces imposed on the column by wind forces acting on the traffic lights.
As I've said, my memory's a bit cloudy, and it seemed a bit pointless to me wasting the time learning all that stuff since we weren't allowed to use it anyway. :?