Minimum Reinf in Footings

[sdz]

Do footings have to have enough reinforcement to meet the requirements of AS3600 8.1.4 Minimum Strength Requirements?
It seems to be a lot of reinforcement for a footing where the calculated moments are much less than the cracking moment.

 

[ljk80oze]

sdz

If the loads are much less than cracking moment (ie acceptable as a plain concrete member) i would just provide minimum temperature and shrinkage reinf. bearing in mind the degree of restraint (if any) and that for members greater than 500 thick, reinf. can be calculated for D=250mm (to each surface).

Cheers

Liam

 

[csd72]

If you use the footings code, this specifies the minimum amount of reinforcement for a given size. I think it it based on 1.2*Mgross.

csd

 

[apsix]

I would say some engineering judgement is required. The minimum strength requirement is used to prevent brittle and catastrophic failure. For many situations footings are unlikely to display that type of failure.
However, for residential footings in Class H & E sites it would be wise to prevent brittle failure and AS2870 requires minimum reinforcement to be maintained if using the Standard Designs: Refer Fig.3.1 Notes 3 & 4 etc.