To take the response a bit further, CAESAR will automatically calculate SIFs and flexibility according to the code.

If you believe the SIFs and flexibility factors from the code to be inaccurate, then you'll need to calculate those externally and input them separately using the SIF input and bend flexibility parameters.

Along the same vein, if your 8D bend has intermediate branches and the like, it's a bit of a challenge to find those points, but I posted the formulas on here some time ago.