Brick with bed joint reinforcement 2

[phuduhudu]

When designing for brickwork here it seems to be normal practice to design unreinforced brickwork but then to put in some bedjoint reinforcement chiefly to prevent cracking. It seems to me that the bed joint reinforcement should greatly increase the perpendicular flexural strength of the brickwork too. The codes on reinforced brickwork seem to refer to cavity reinforcement and the like and not the sort of reinforcement that sits in the bed joints. Does anyone have any experience designing with bed joint reinforcement. Carl Bauer

http://www.bauerconsultbotswana.com

 

[StephenEd]

Some codes allow horizontal joint reinforcement for consideration as minimum horizontal steel.

Is this what you're after, or are you interested in the actual flexural properties?

 

[phuduhudu]

I am interested in the actual flexural properties of a brick wall with bed joint reinforcement. One concern of mine is can it be relied on because it has very little cover in the mortar and often will have no cover to the bricks since only the very best brick layers will halve the mortar and put the reinforcement right in the middle of the 10mm joint. Carl Bauer

http://www.bauerconsultbotswana.com

 

[dougantholz]

Carl,
I have used horizontal joint reinforcement to count toward the minimum shear steel in a while. Typically this is in CMU, but I have also used it on brick walls (although only in multi-whyth aplications. In order to use it for steel needed in order to acturally resist shear loads higher than the capacity of the brick and mortar, I would require special inspection. Masonry in the US is typically the lowest in predictibility of workmanship (sorry if this offends masons but its true).
HTH

 

[ishvaaag]

A leaflet that I have recommends to lay every 40 cm the trusses in the bedjoints and vertically every 2.75 m (alsp with the depth against wind).

Then respect calculations recommends to go for Fd (compressive design strength of the masonry)=30 kgf/cm2.

So as a start and for horizontal flexure assume such compressive strength in a triangular stress block or if you dare a rectangular one.

The usual E=500fc_average I think should refer to the brick actual material one, not Fd, otherwise I think will give too much overconservative predictions of deflection. Even higher estimates 750 or 1000 fc_average may prove better to assess deflections.

EC-6 must be the Eurocode dealing with this, I have not it.

 

[ishvaaag]

If you have access to

The ENgineering Handbook
Ed. in Chief Richard C. Dorf
CRC Press

you will see that both approaches triangular stress "elastic" block and rectangular stress block are used.

At 25 or 30 kgf/cm2 one may assume most concrete or cooked brick masonries are to stay elastic.

The reference has also some E data but is in general more aimed at concrete masonry units' masonries.

 

[valleyboy]

Carl

I have used bed joint reinforcement in cavity walls to increase the ability of the panels to span horizontally between supports.

There is some information on the following web site:-

http://www.brc-building-products.co.uk

I think there is also an EXCEL spreadsheet for designing such reinforced masonry panels on the Institution of Structural Engineers web site /

http://www links

/ spreadsheets for structural engineering / spreadsheets.

I'm not sure about the avalability of the BRC products in Africa !! I'm sure you could find a similar product in your area, though.

Happy hunting.

 

[RiBeneke]

It seems to be common practice to ignore the nominal welded wire ladder reinforcing ("Brickforce&quot used in brick bed joints. The South African code for unreinforced masonary (SABS 0164-1) makes no adjustment to the flexural strength of masonary to allow for reinforcement. The other code for reinforced masonary only makes reference to types of steel bars and prestressing like those used for reinforcing of concrete.

The control of placement accuracy and adequate bond would be a concern if the welded wire reinforcement were to be considered structural to provide flexural strength in masonary. There are also concerns that the wire, even if galvanised, does not have a very long life in outside walls in wet climates (Botswana is excluded here) before corrosion begins.

In the case of single-leaf walls (half-brick thickness in British terminology) the thin wire cross-sectional area and small eccentricity from the centroid of bending would only make a small contribution to the overall stability, particularly if strong arch action is developing in the masonary.

If you were to do the calculation ignoring arch action, you would probably also find that the wire reinforcement would contribute an insignificant amount to the stiffness and servicibility limit state of the wall, although I agree with suggestions that it could contribute usefully to the ultimate (collapse) limit state.

I have always used normal reinforcing bars (Y8 etc) rather than welded wire in the bed joints where reinforced lintels etc are required.