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D10.A.7 Column Interaction

The column interaction values may be obtained by using the design parameter TRACK 1.0 or TRACK 2.0 for the column member. If a value of 2.0 is used for the TRACK parameter, 12 different Pn-Mn pairs, each representing a different point on the Pn-Mn curve are printed. Each of these points represents one of the several Pn-Mn combinations that this column is capable of carrying about the given axis, for the actual reinforcement that the column has been designed for. In the case of circular columns, the values are for any of the radial axes. The values printed for the TRACK 1.0 output are:
  • P0            = Maximum allowable pure axial load on the column (moment zero).     
  • Pnmax   = Maximum allowable axial load on the column.       
  • P_bal     = Axial load capacity of balanced strain condition.       
  • M_bal    = Uniaxial moment capacity of balanced strain condition.      
  • E_bal     = M_bal / P_bal = Eccentricity of balanced strain condition.      
  • M0           = Moment capacity at zero axial load.    
  • P_tens    = Maximum permissible tensile load on the column.      
  • Des. Pn  = Pu/FR where FR is the Strength Reduction Factor and Pu is the axial load  for the critical load case.      
  • Des.Mnx =   Mux*MMAGx/FR where FR is the Strength Reduction Factor and  Mu is  the  bending moment for the appropriate axis for the critical load case.  
  • Mu  = √(Mux.Mmagx)²+ (Muy.Mmagy)²
  • e/h          = (Mn/Pn)/h      where h is the length of the column