Why when modeling a little more weight does the results increase exponentially to become severally over-stressed in AutoPIPE's code compliance report?
Distributed load = 21000 N/m, A12 results ratio = 0.10
However when only the Distributed load is increased to 22000 N/m, A12 ratio = 4.30.
How can modeling such a small amount of weight make such a significant difference in the results?
Best to review the results Displacement sub-report in both cases:
Distributed load = 21000 N/m, displacement = 43.9 mm down
Distributed load = 22000 N/m, displacement = 794.3 mm down
Clearly the Soil properties are inadequate to support the heaver distributed load.The pipe is slipping through the soil bearing spring supports.
Review the soil properties to be sure they have been entered correctly based on soil testing reports from a reputable source. This analysis example requires a stiffer soil property to support the heaver pipe.
Adjust the soil properties as needed or reduce the vertical reaction force on the pipe.
Model Soil Properties with Soil Calculator and Underground Piping