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UBC 1808.2.2

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I have posed this question before to the list, received some input, but am asking again.
UBC 1808.2.2 limits compressive stress of concrete to .33f'c and compressive stress of steel to .34fy for drilled, cast in place piles. I do not know from where this requirement comes but would surely like to know.
ACI 318-99, Chapter 21 also has requirements for drilled, cast in place piles, some similar to UBC although no limitation on compressive stresses in dcip piles.
I have a condition where I am stuck with the loads, pile diameters, pile quantities, compressive strength of concrete, etc.. My compressive stress is ranging from .4f'c to .76f'c for concrete (similar numbers for steel). Aside from this, pile design is adequate.
Question 1: Does anyone know why this limitation is in the code? The leading response to this in the past has been "it is a factor of safety for pile capacity due to unknown pile quality down a 50' deep hole".
Question 2: What could I do to the pile to compensate for not meeting the compr. stress limitation. Higher level of quality control during concreting....provide transverse reinf. full length of pile....something.....anything....
Question 3: Is there anyone out there on a code writing committee who would have insight to this issue?