Steel Pile Thickness

[Togel]

Given that 10" concrete filled reinforced steel pipe piles with an axial design load of 75 tons are the design requirment for a building foundation, and that the piles are closed end and driven to a depth of an average of 47', How does one calculate the required pipe wall thickness in order to resist any significant distortion (less than 10% of pipe diameter change. The soil is described as creamy, loose to dense, water logged, calcareous, gravelly silty sand limestone formation 'marl'. The SPT rod sank 2' with one blow. The underlying bedrock formation is a uneven, pitted, fractured coralline limestone. The ground water has also has high quantities of sulfates and chlorides. As a result, the design corrosion rate of the piles is estimated at 0.08 mm/year. The design calls for a minimum pipe wall thickness of 0.365 inches. Is this adequate?

 

[ishvaaag]

I am not familiar with the details of dynamic piling. In any case, you stand at D/t ratio 27. Full plastic design moment (a function exclusively of local slenderness for pipes) is available for Fy=36ksi since D/t=57 and for Fy=50ksi D/t=41 and of course for lower values.

Further lower D/t ratios are sometimes exacted for braces in seismic (dynamically) solicitated pipes. These are for example D/t=36 for Fy=36 ksi and D/t=26 maximum for Fy=50 ksi. Some authors are even more exigent in relative thickness.

In any case it seems that the specifier has selected one diameter to thickness ratio akin to the more exacting in the LRFD for seismic excitation. I bet a good shake of a big earthquake on a main brace (these are) is as damaging as the hammer blow of piling...if only because the pile drivers do only to refusal, this normally meaning one value of resistance to penetration that is clearly capable enough to deliver the low capacities exacted of the piles out of their irregular buildup, but they are not wanting to damage the pile in installation. So it looks to me from this verbose reasoning that the thickness is enough and only uncommonly able to damage boulders in the path could mean something bad to your nailed pipes.