Engineering analysis + design software

Software Option for Bridge plus and Civil&Structural plus versions

Geotechnical Analysis

Unlike some structural analysis software LUSAS Civil & Structural plus and LUSAS Bridge plus software products, when used with appropriate geotechnical, nonlinear, dynamic and thermal/field software options, provide a range of soils-specific and general structural engineering analysis tools to enable finite element modelling in 2D or 3D of both ground and structure in a single model. 

Multiple analyses can be solved within each model, and state-of-the-art linear and quadratic element libraries; advanced material models; and linear and nonlinear joint models allow a range of soil-structure engineering problems to be solved


  • LUSAS models are created using feature-based geometry methods (points, lines, surfaces and volumes) and built-in associativity, a key feature of the LUSAS Modeller, ensures that if the model geometry is amended, all assigned loadings, supports, mesh and other attributes are automatically updated to suit.
  • CAD import / export facilities permit importing of point and line data from DXF files; points, lines, surfaces and volumes via IGES/STEP interafaces; and triangulated surface data through STL. CAD-style drawing tools provide an array of modelling utilities such as copy, rotate, scale, transform, extrude etc.
  • For 2D modelling splines can be created from terrain points data and swept to create strata. Surfaces can be defined from bounding points and lines, and swept to define a soil mass. Structural and soil components can be grouped for modelling purposes. For 3D modelling, planar or curved surfaces can be swept for multiple volume creation, and intersection and subtraction commands provide the means to slice volumes or create voids.
  • Automatic 2D meshing (using quadrilateral/triangular elements) and 3D meshing (using tetrahedral/pentahedral/hexahedral elements) speeds up the modelling process. Various mesh refinement methods are provided.
  • Calculate initial stress states providing K0 data and apply to any ground profile.
  • Constitutive soils models include Mohr Coulomb, Modified Cam Clay, Tresca, Von Mises, Drucker Prager, Duncan-Chang, Hoek-Brown.
  • Two-phase material properties can be added to selected materials to permit modelling the deformation of undrained/fully saturated and fully-drained/unsaturated porous media, and slow consolidation process. Draining and filling curves can also be specified for partially drained materials.
  • Define phreatic surface levels to determine pore water pressures where the water table is known. Determine levels and pressures between those locations based on porosity and hydraulic conductivity. Alternatively define pore pressures based on piezometer readings or borehole data.
  • Model the variation of soil properties with depth by defining soil profile variations, with LUSAS interpolating between defined locations.
  • Nonlinear springs model active/passive soil joints. Interface meshes permit joining of the soil / structure. Gain / loss of contact, and skin friction can be considered. 
  • Specify a matrix of properties to represent a pilecap sitting on a group of piles in a 3D model.
  • A Tri-linear (active/passive) earth pressure joint material wizard simplifies the modelling of a variety of soil-structure interaction problems, creating a piecewise linear joint material attribute with properties that vary with depth. Multiple attributes can be defined to represent layers of soil or changes in properties due to the presence of water.
  • Use a Phi-c reduction analysis to assess soil stability and safety factors for soil represented by Mohr-Coulomb or Hoek-Brown material models.
  • Use time dependent loading for impact or time history and use non-reflective boundaries to transfer energy out of the sub-model for realistic modelling of response and interference.
  • Use branched analyses to study safety factors at several stages of construction without terminating the solution.

Typical applications

LUSAS is used in all areas of civil, structural and bridge engineering for linear, nonlinear, seismic, blast, buckling, impact and thermal/field analysis. It can be used on all types of structures from simple slabs, buildings, towers, tanks and bridges  through to heavy civil engineering structures such as dams, docks and tunnels. General geotechnical and soil-structure interaction capabilities include:

  • Construction sequence modelling - involving excavation / construction with insertion and removal of temporary members used for propping and jacking etc. 
  • Embankment /slope stability assessments and stability checks on adjacent structures due to temporary excavation. 
  • Backfilling of excavations and cut and cover tunnel structures. 
  • Settlement and consolidation including pore water pressure modelling. 
  • Dewatering and seepage modelling of partially saturated fluid flow through porous media, such as seepage of water through an earth dam, where the position of the phreatic surface is of interest. 
  • Modal and time history dynamics involving material damping, nonlinear behaviour, soil plasticity, boundary behaviour and springs/dampers. 
  • Soil-structure interaction analysis including vibration analysis from pile driving impact assessments on nearby buildings and response of buildings to emitted vibrations from rail tunnels. 
  • Lateral displacement analysis of piles and pile groups 
  • Integral bridges

Dependent software options

Use of the Geotechnical software option will require one or more of the following other software options to be accessible, depending upon the modelling to be carried out..

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LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2022. Last modified: December 01, 2023 . Privacy policy. 
Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.