Reinforced Raft Foundation


The FDR+ program can be used to design eccentrically loaded boundary foundations that are connected to a reinforced concrete slab with a rigid joint. In the design, the centring moment, the centring tensile force and the soil pressure are determined with consideration of deformations. Optionally, a restraint in the wall can simultaneously be considered. The centring in the connected reinforced concrete slab is performed in accordance with J. Kayna (Bautechnik magazine 05/1969).

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Discover now more programs from the section Foundation!

  • Wall and facing optionally of masonry or reinforced concrete
  • Reinforced concrete with selectable concrete qualities and steel grades
  • Different materials for the foundation, the slab, and the wall
Structural system
  • Square and rectangular foundations
  • Eccentric arrangement of the wall
  • Any geometry definable for the wall, the slab and the foundation to derive stiffness
  • Pinned or flexurally rigid connection of the slab with user-defined stiffness factor
  • Wall head with or without restraint or pinned support



  • Any number of horizontal layers
  • Freely selectable soil parameters
  • Permissible base pressure resistance based on empirical values of DIN 1054


Ground surface:

  • Horizontal or continuously ascending
  • Any number of polygonal ground-surface sections



Stagnant groundwater can optionally be taken into account at any height level


  • Any wall loads for uniaxial effects of actions:
    • Vertical axial force Vz
    • Horizontal concentrated loads in the x-direction
    • Concentrated moments about the y-axis
  • Optionally, additional loads can be defined in the foundation/slab connection if the connection is pinned.
  • Optional inclusion of the self-weights of the wall, the facing, and the foundation independently of each other.
  • Free assignment of loads to types of actions according to EC 0 as well as to concurrency and alternative groups.
  • Automatic combination of loads for the calculation of the decisive design load case for each verification.
Reinforced concrete design (internal stability)
  • Bending design at the foundation/slab connection
  • Examination whether an unreinforced execution is possible
  • Optional calculation of the connecting reinforcement in the upright reinforced concrete wall
  • Centring in the flexurally rigid connected slab
  • Simultaneous restraint in the wall and the slab is optionally selectable
  • Durability verification via exposure classes
  • Verification of the concrete compression stress and the steel tensile stress at the connection to the slab
  • Crack width verification at the connection to the slab
  • Consideration of different minimum reinforcement quantities
  • The reinforcement dialog allows the definition of any reinforcement and arrangement
Geotechnical verifications (external stability)
  • Simplified verification with base pressure resistances (either user-defined or taken from tables of DIN 1054)
  • Optional verifications based on the accurate calculation method:
    • Overturning
    • Sliding
    • Ground failure
  • Optional settlement verification
  • Serviceability via the verification of the gaping joint
  • Calculation of deformation and torsion with consideration of the centring moments and the stiffness conditions
Document file formats
  • PDF
  • Word
  • Printer
  • Various output profiles available for selection (brief, detailed, user-defined)
  • Selectable graphic scales and font sizes
  • Detailed output of individual load cases
  • Overview of the decisive load case combinations and their assignment to the design situation (persistent, transient, accidental and earthquake)
Reinforced concrete design
  • Decisive base pressure distribution for the different design calculations
  • Bending design at the top and bottom of the foundation and detailed tabular output
  • Details concerning internal forces, stiffness as well as centring forces and moments in accordance with Kanya
  • Graphical representation of the reinforcement distribution
  • Design of the connecting reinforcement, if applicable
  • Details concerning the stress verification and the crack width verification
Geotechnical verifications
  • Tabular and graphical output of the selected decisive actions and base pressures for each selected geotechnical verification
  • Verifications in the ULS (simplified with base pressure, overturning, sliding, ground failure)
  • Verifications in the SLS (first and second core range, settlements, and torsion)
Transfer options
  • Slabs by Finite Elements PLT
  • Isolated Foundation FD+
  • Block Foundation FDB+
  • Mast Foundation FDM+
  • Strip Foundation FDS+
  • Ground Failure Analysis GBR+
  • Beam on Elastic Foundation BEB+
  • Soil Settlement SBR+
Load import
  • GEO Building Model
Geotechnical standards
  • EN 1997
  • DIN EN 1997
  • ÖNORM EN 1997
  • PN EN 1997
  • NF EN 1997
  • DIN 1054
  • DIN 4017
  • DIN 4019
  • ÖNORM B 4435-2
Reinforced concrete
  • EN 1992
  • DIN EN 1992
  • ÖNORM EN 1992
  • PN EN 1992
  • NF EN 1992
  • BS EN 1992
  • DIN 1045

Support resources