RC Elevated Slab Design Strip

I'm currently designing a RC Pile supported foundation. I'm designing it as a elevated slab w/ columns equivalent to the piles provided by the geotech. 

I have design strips spanning both latitude and longitude b/t piles and designated a 2-way system. I had a couple questions concerning this design.

1. In a few cases a column load is directly in the middle of 4 piles. I was expecting the 4 strips (2 lat, 2 long) to split this load equally. Instead it looks like the 2 lat split the load fully, then the 2 long strips split the load. This doesn't seem to exhibit a 2-way slab behavior as I was expecting. Can you further expand on why this is so? Do the long. and lat. strips not act simultaneously? If not, how would I model the design strips to have the slab behave like a true 2-way slab?

2. When would you utilize a 1-way slab instead of a 2-way slab and how would model the design strips in order to do so?


Philip Chesney