Reinforcement laps in continous footings

[mar2805]

Hi folks!
Ive found few articles where a general rule of laping reinfrocement in continous footing is done by providing corner bars and laping them at the outsied face of the footing like in the link here:
see rebar laps in plan view

http://www.beforethearchitect.com/Articles-FDN Rebar.htm

Why cant rebar be lapped with same principals that are give for beams:

http://www.buildinghow.com/Defaultnew.aspx?ch=53

 

[dik]

If I have longitudinal bars in strip footings, then I extend straight bars to near the corner and use cornerbars. This provides some adjustment in the bar length. The inner bars have a 90 deg hook to the outer face of the footing. Generally not much need for longitudinal bars... usually have them at the dowels to a concrete wall over.

Dik

 

[mar2805]

"Generally not much need for longitudinal bars"
Agree with you on that but I would always provide minimum reinforcement in the longitudinal direction since the load on the strip is never of the same intensity (door openings, garage doors, Windows, soft spots under the strips).
This can all couse bending moments, not big, but just to be shure.

 

[AELLC]

Long bars in a wall footing are very necessary in wood-framed structures to prevent distress in the footing/conc stem due to uneven soil settlement.

 

[hetgen]

Hi Mar,

The first detail is used for concrete section with closing corner; normally the bent bar in the corner will have larger bent radius to avert bearing problem inside the bent bar. I don't see the need to provide this detail in strip footing unless in-plan bending is expected.

HTH

 

[dik]

Mar2 and ALLEC...

If long bars are req'd, then I usually place them at the location of the wall dowels... The steel placer often has support bars at the outside edge if required. For strip footings, often have plain concrete for residential type work.

Dik

 

[AELLC]

Around here (Phoenix area) there's a lot of lawsuits because of unreinforced plain concrete residential footings.

 

[mar2805]

@hetgen
"The first detail is used for concrete section with closing corner; normally the bent bar in the corner will have larger bent radius to avert bearing problem inside the bent bar. I don't see the need to provide this detail in strip footing unless in-plan bending is expected."

You mean bending moment in the longitudinal direction?
But a narrow strip will only "bend" in longitudinal direction.

 

[hetgen]

Hi Mar,

See attached diagram showing plan view of a concrete section with closing corner. This kind of in-plan bending could happen if the strip footing is attached to a retaining walls.

 

[mar2805]

Yes,ok,
this would apply in a ending column to beam situation and not in the footing.

 

[dik]

AELLC... what seems to be the problem? We've used them for years without incident. Not thick enough? One armoury that I did a report on that was constructed in early 1900's had plain concrete footings taking major loads but were stepped Had 4 or 5 different 'layers' of progressively smaller size.

Dik