PTB-4-2013 Eample E4.3.7 mystery variables
PTB-4-2013 Eample E4.3.7 mystery variables
(OP)
The ASME Code Section VIII Division 1 solution method presented in Example E4.3.7 of PTB-4-2003 provides and equation for the combined force factor f2 that consists of variables FS [axial force] and MS [net section bending moment] for which I am unable to locate a specific reference to in Part UG or mandatory Appendix 1. I am particularly interested in any specific Code reference to the underlying reasoning for the numerical sign convention assigned to these loads in this example.





RE: PTB-4-2013 Eample E4.3.7 mystery variables
For the numerical sign convention, the bending moment causes compression on one side of the tower and tension on the other. Therefore, a plus or minus is used to determine the maximum and minimum loadings. It is important to check the negative moment as if the junction will be in compression under pressure, the Code requires a more detailed analysis.
RE: PTB-4-2013 Eample E4.3.7 mystery variables
RE: PTB-4-2013 Eample E4.3.7 mystery variables
RE: PTB-4-2013 Eample E4.3.7 mystery variables
Remember that the Code is not a design guide. Good engineering practice must be followed to comply with the rules. That's what you are seeing in PTB-4.
RE: PTB-4-2013 Eample E4.3.7 mystery variables
The axial forces are due to weight of the tower, so yes they act downward. The bending moment is likely due to wind load, so it would act as an overturning moment.
RE: PTB-4-2013 Eample E4.3.7 mystery variables