Looking at the image above, it can be seen that the contractor lapped and cranked the column reinforcement to an entirely new position. In your own opinion, which engineering judgement or principle informed this decision taken by the contractor, or is it plain lack of structural engineering knowledge?
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I think this is down to lack of structural engineering knowledge because, any structural engineer will know that there is no way the axial load from the column above will be properly and effectively transferred to the starters, hence the purpose of providing the column is defeated.
This was purely lack of structural engineering knowledge because if the engineer was to support the top column, which appears to have no room for it’s own pad footing, then a transfer beam should’ve been introduced to take up the point load, which eventually would be supported by the column below (the one that has a pad footing) & an adjacent column along the same grid.
The contractor judgment is wrong, based on engineering principles.columns are provided in structures to transfer axial or biaxial load of the building to the foundation. The contractor want to support an existing columns with a new column. But the base of the existing column doesn’t allow the new column to be closed the building. The cranking of the column reinforcement will generate a moment. Which
was considered for the new column.
The answer is lack of engineering knowledge.
This is a boundary issue,encroachment into other’s plot is not allow.So, the pad foundation could not go the right position & dimensions.Strap foundation would have suffice.
Cranking of columns is not recognised by code of practice. Cranking in d code refers to the one occuring at lapping section.
This pics depicts an unsatisfactory engineering judgement. The columns is underengineer in a lot of ways and the load carrying capacity may soon be breached.
The contractor however, may have render the column to be redundant and redistributed the load to anoda column where dat one will just serve as fancy column.
Its lack of structural engineering knowledge for me. The axial load from the column has to be transferred safely at the laps and according to Eurocode, the lapping of bars should be kept at a minimum of 45 x diameter of the main reinforcement.
Cranking should not exceed the ratio of 1:6 and it is done when there is a reduction in the column cross section. The job done by the contractor is wrong and will cause a failure, the idea is that there is an offset planted column due to some architectural restriction (ex: open office space) so in this case the column should be supported by a short cantilever, and the cantilever will supported by the column neck that will transfer the load to the footing
It should be designed as a corbel and requires shear and tension reinforcement for point load of column at the tip of corbel and this extra moment will have impact on foundation design.Foundation need to be checked for downward CG should lie within 1/3 of base width otherwise bearing pressure area of foundation pad should be reduced for this eccentric loading(b-2xe) in stead of full width of footing bearing area…
theirs no engineer who supervised this construction.