Civil and Structural engineering

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Load types and combinations

LUSAS Civil & Structural provides a comprehensive range of general loading types to cater for most circumstances. Envelope and load combination facilites help you get the most from your results.

Structural, prescribed and thermal loads are feature based loads that are assigned to the model geometry and are effective over the whole of the feature to which they are assigned. Discrete loads are feature independent. Variations in loading can be applied to all feature load types according to the feature on which they have been assigned

General load types

  • Structural loadings include gravity, concentrated, distributed, face, temperature, stress/strain, and beam loads.
  • Variations in loading can be applied to all feature load types according to the feature on which they have been assigned.
  • Specify initial displacements, velocity or acceleration using prescribed loading options.
  • Use discrete loads to distribute a loading pattern over full or partial areas of the model independent of the model geometry.
  • Define compound loads (to define load trains) from a set of previously defined discrete loads and assign to a model as one loading.
  • Use thermal loads to describe temperature or heat input for a thermal analysis or coupled structural / thermal analysis.
  • Apply variations in loading to all feature load types according to the feature on which they have been assigned.

Prestress and post-tensioning loading

Prestress / post-tensioning in LUSAS is suitable for beams, slabs and volumes, and for ceratin design codes can incorporate time-stage with creep and shrinkage. LUSAS calculates equivalent nodal loading due to any tendon prestressing or post-tensioning and assigns these forces automatically to beam, shell, or solid elements of a model for a chosen loadcase or set of loadcases. Span-by-span, progressive placement, balanced cantilever and incremental launching time staged construction methods are supported. 

Design codes supported include:

  • AASHTO LRFD 2nd Edition
  • AASHTO LRFD 5th to 7th Edition
  • BS5400-4:1990
  • DD EN1992-1-1:1992 Eurocode 2
  • EN 1992-1-1:2004 Eurocode 2
  • JTG D62-2004

Beam (line), shell (surface) and solid (volume) modelling of concrete is supported.

In summary:

  • Define tendon profiles and view the developing tendon shape in real-time as it is being defined, or copy and paste data from a spreadsheet. Tendons can also be generated by selecting lines, arcs or splines that are defined or imported into LUSAS Modeller. Manual definition by coordinates in 3D space or by defining coordinates in two 2D planes is supported. 
  • Locally defined tendon profiles can be used anywhere in the model and any number of times. 
  • Define tendon properties and values/settings relating to instantaneous and time-dependent losses. 
  • Elastic shortening due to stressing of other tendons according to the selected design code or user-defined percentage losses is taken into effect. Time dependent effects can also be considered.
  • Simply assign the tendon loading by dragging and dropping it onto selected line, surface or volume features in a model for a single or a range of loadcases. 
  • Produce graphs of tendon prestress force after time-dependent losses. 
  • Add tendon properties, profile, loading, losses and setting-out data for all tendons assigned to a model to a model report.

Envelopes and Combinations

Basic, Smart and Code-specific load combination facilities are a key feature of LUSAS Civil & Structural and allow manual or fully automated assembly of design load combinations. From these, envelopes, contour and deflected shape plots, and results graphs can be readily obtained for any loadcase under consideration.

  • Basic load combinations allow for manual definition of loadcases to be included and load factors to be used. In situations when superposition may not hold true, the factored loadcases from these combinations can be used to create a single loadcase for a nonlinear solution to be found.
  • Envelopes of multiple loadcases provide maximum and minimum results.
  • Smart Combinations generate maximum and minimum results, taking account of adverse and relieving effects, substantially reducing the number of combinations and envelopes required.

Smart Combination Dialog

Design code load combinations

Use the Design Combination wizard to assign a loadtype to a loadcase, envelope or basic combination for a supported design code. Based on the assignments and settings made, design code load combinations for those load types are automatically generated by LUSAS Modeller.

Loadcase / loadtype definition

Combination options

Design combinations for the following codes of practice are supported:
  • AASHTO 7th Edition
  • AS/NZS 1170
  • BD21/01
  • BD37/01
  • CSA-S6-14
  • EN1990 (Buildings) Recommended Values
  • EN1990 (Buildings) to Irish National Annex
  • EN1990 (Buildings) to UK National Annex
  • EN1990 (Bridges) Recommended Values
  • EN1990 (Bridges) to Irish National Annex
  • EN1990 (Bridges) to UK National Annex
  • GB 50009 - 2012
  • JTG D60-2004

Response spectra

Design code response spectrum data for the following codes of practice are currently supported:

  • ASCE 7-10 (2010)
  • ATC-40 (1996)
  • China GB 50011-2010
  • EN1998-1:2004 Design (Horizontal)
  • EN1998-1:2004 Elastic (Horizontal)
  • FEMA 356 (2000)


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Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.