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The document presented by Sir Umer clearly says that this stress increment should not be taken even in case of earth quack loads if 0.75 reduction factor has been already used in load combinations. More over, in sizing of footing, we go for ASD approach because bearing capacity given by geotechnical engineer is based on the concept that full factor of safety of 2-3 is applied on soil strength and no loads are increased. This is ASD methodology. So to be compatible, we also go for ASD while sizing of foundation. So in my opinion, if you are using load combinations which are carrying 0.75 reduction factor, you can not increase soil stress by 33% even not for earth quack loads. but if you are using the load combinations which are not having 0.75 reduction, then you can increase this stress as 33% but just for those cases where two or more than two transient loads are acting simultaneously.

Dear Khalid ! i go through your model and upto my understanding your model is OK but 2 corrections are required. 1) As you mention that the zone of the building is ZONE 3.So you must have to check the Beam Column Joint Ratio which you are saying that it is not done.it is because you have overwrite the sway property from Sway Special to Sway Intermediate.So change your sway type from Sway Intermediate to Sway Special then you will get the required B/C Ratio. 2) In defining the slab you have define slab as a MEMBRANE and membrane takes in-plane stresses only. And in reality the slab also take out of plane stresses by deflecting/bending. So define slab as a SHELL THIN then it will take both in-plane and out-plane stresses. Have a look to the snaps and the model with the two corrections i have made. Sari Pul_V13.rar

There are two noticeable references mentioned in this thread. One is specific to Load Combinations(ASD stuff) and subsequent 1/3rd reduction, the other is about C12.13.4 of ASCE 7-05: 25% reduction of seismic overturning moment for the case of Equivalent Static Lateral Force Procedure. For some reason, all the replies have been focused on ASD Load Combinations and subsequent 1/3rd reduction. Anyways, ASD is old in a matter of few years would be completely wiped out of the scene for foundations. The current practice in industry is to use LRFD for foundation design. Moreover, make sure you touch base with the Geotechnical Engineer. Sometimes geotech reports specify what could be done or not with regards to thread subject. Thanks.

yes Waqas you got it right..No increase in 0.75load combinations as in ASCE/ACI

How can I calculate the required splice length for column? What will be effect on the structure, if someone on site provide the column splice length less than the required length? Will it create problem in load transfer or moment or stress? What is the minimum column splice length can be provided? (With ACI Code Reference) Regards,

you capacity would be reduced by (Asprovided)/(Asrequired)..

Code requirements regarding splicing of reinforcement, including minimum splice length, are given in ACI 318-05 Chapter 12. These requirements are summarised and elaborated with detailed examples in PCA Notes on ACI 318-05. In addition, last article in chapter 5 in 'Design of Concrete Structures' by Nilson provides a good description of reinforcement splicing, along with an example on calculation of compression splice for a column. In general, provision of a splice length less than than that required by the code, will negatively affect the load or moment carrying/transferring capacity of the column. However, extent of this capacity reduction will depend upon detailed analysis and comparison of 'code required length' and the 'actually provided length'.

I just came across this. Here is an article by AISC that addresses that. Its not allowed anymore and reasons are in the article. 13rd stress increase AISC.pdf