oengineer
Structural
- Apr 25, 2011
- 708
I am using RISAFoundation to design timber foundations. I am wondering if anyone knows of acceptable values to use for the stiffness values, expressed in kips per inch (k/in). I divided the compression capacity (31 kips) by the max settlement value (1 in) mention in the soil report. This gave me 31 k/in.
I noticed when I use a greater capacity pile without increasing the compression stiffness value all my piles pass with no problem. However, if I increase my compression capacity along with my compression stiffness, my pile continues to fail and the load at which it fails continues to increase.
For example, say I change it to 37 kips capacity, with the same 1 inch deflection, would give me a new stiffness value of 37 k/in. According to RISAFoundation my pile will fail. Is it too conservative to use a small stiffness value? As long as the loads stay the same, I believe that my piles should pass if I use a grater capacity pile at a lower depth. Is this thought correct?
I noticed when I use a greater capacity pile without increasing the compression stiffness value all my piles pass with no problem. However, if I increase my compression capacity along with my compression stiffness, my pile continues to fail and the load at which it fails continues to increase.
For example, say I change it to 37 kips capacity, with the same 1 inch deflection, would give me a new stiffness value of 37 k/in. According to RISAFoundation my pile will fail. Is it too conservative to use a small stiffness value? As long as the loads stay the same, I believe that my piles should pass if I use a grater capacity pile at a lower depth. Is this thought correct?
