I am requesting an Mu of 0.6 to model the friction reaction of a pipeline spool sitting on the seabed.

For the pipe alone, this gives good results, and the vectorial addition of the two forces normal to the reaction are adding up to exactly 0.6 Fy as expected. However, when I introduce a concrete weight coat in the form of insulation, the horizontal friction force does not get above around 15kN per support, only amounting to some 15% of the vertical reaction, and I cannot understand why?

Thanks
Daryl

Review the explanation in the CAESAR II Technical Reference Manual, beginning on page 6-16.