Modification of internal forces

 

There is possibility to modify internal forces for each type of member separately and these modifications is taken into account for design and check too. The modification of internal forces allows to user:

• set modification for each type of member (beam/column/rib/beam as slab)

• set limit for each component of internal forces (N, My, Mz, T, Vy, Vz)

• switch OFF/ON off each component of forces per type of member

The modification can be done generally for whole structure in concrete setting or for each member in concrete member data.

The modified internal forces are presented in command Internal forces in concrete only for dimensional internal forces (values with index Ed, for example MEd)

There are supported five types for modification of internal forces for each type of member

• Auto – automatic calculation according value of bending moments and shear forces. If ratios of bending moments and shear forces are lesser than limit ratio, uniaxial calculation (Uniaxial Y or Uniaxial Z depending on values of bending moments and shear force) is used and smaller values of bending moments and shear forces are neglected. Otherwise biaxial method is used.Limit ratio is defined in concrete setting, see "Concrete setup"
• Uniaxial Y –uniaxial calculation around Y of cross-section axis is used, it means
  • for beams and columns : only values NEd, MEdy, VEdz and TEd are taken into account
  • for beam slab and rib : only values NEd, MEdy, VEdz is taken into account
• Uniaxial Z – uniaxial calculation around Z axis of cross-section is used, it means

  • for beams and columns : only values NEd, MEdz, VEdy and TEd are taken into account

  • for beam slab and rib : only values NEd, MEdz, VEdy is taken into account
• Biaxial – biaxial calculation is used, it means all components of internal forces are taken into account
• User – user can select which component of internal forces will be taken into account
• User with limit - user can select which component of internal forces will be taken into account and can define limits for each component. There are three possibilities for definition limit:
  • No - without limit
  • Abs - only internal forces with absolute value greater as input limit is taken into account
  • Rel - only internal forces with the relative ratio greater as input limit is taken into account. Relative ratio is calculated:
    • for normal force, bending moment and torsional moment:ration N/Mres, ratio = MEdy/Mres, ratio = MEdz/Mres, ratio = T/Mres,
    • for shear forces: ratio =VEdy/Vres, ratio =VEdz/Vres

    where

    Mres - is resultant of bending moments

    Vres - resultant of shear forces

There is possible to set for the rib ,if recalculation of positive bending moment will be used or not . This option is available only if normal force is OFF and type of modification is User or User with limit.If recalculation of positive bending moment is ON, then normal force is neglected and additional bending moment corresponding to the recalculation to the centre of gravity of the whole rib cross-section is added. Otherwise normal force will be neglected without recalculation, see "Concrete setup"

Type of modification which is used in calculation is presented in detailed output in command Internal forces in Concrete