Minimum Reinforcement Requirement in Pad Footing

[tngv752]

Not sure that I have to use the min. reinforcement in the pad footing (p=1.4/Fsy).

Because, there will be a lot reinforcement in the pad footing in which I don't need for strength of the footing.

 

[frv]

It's still a good idea to provide min reinforcement for temperature/shrinkage.

 

[sandman21]

ACI 318-05 7.12.2.1, for shrinkage and temperature min. reinforcement.

 

[JAE]

Please read through this similar thread:

thread592-215546

 

[asixth]

tngv752,

AS3600 specifies a minimum quantity of 0.002bd which is about 30% less reinforcing than the ACI approach (I'm assuming your quoting ACI). The commentary to AS3600 cites the reduction in minimum reinforcement to the "lack of restraint which may cause tension" and the unliklihood of a "sudden catastrophic collapse" occuring from the failure of a pad footing.

How many of these footings are required for your building?

I don't think the saving in materials would be worth the effort. Nobody will be questioning the efficiency of your design when you are providing minimum reinforcement.

 

[miecz]

Also, see thread507-194414.

 

[csd72]

asixth,

Frost is more prevalent in the US hence the larger minimum reinforcement.

tngv752,

If you can justify that the footing meets all the criteria of a plain concrete member then you can avoid using the minimum reinforcement criteria. Even if it has some reinforcement in it it can still be treated as plain concrete.

 

[miecz]

More in thread507-174536.

 

[tngv752]

Thanks for the answers.

I think in the old day, the engineer didn't sometimes design reinforcement for temp. and shrinkage control in which less reinforcement was used. Nowadays, more researches and experiences prove that shrinkage and temp are more critical to control crack and some formuler are developed for more min. reinforcement required.

 

[samay]

I am currently working in a contracting firm. I have recieved a design for a G+1 bldg of 80*30m. However the bldg do not have any expansion/contraction joint. I asked the consultant so many times to include the joint but they refused to do so and the temperature in the area reaches 50 celsiues during summer and 5 during winter. And some times there is great difference in temprature b/n day and night as it is a desert. Do u thing the designer is correct?

 

[asixth]

csd72,

living in a lovely part of the world where the temperture never goes below freezing, what effects does frost have on your footing?

This is certainly a topic that isn't discussed in the design office or at the universities. I believe it may have something to do with water ingress that causes cracking when freezing over but I am not entirely sure?