Bridge analysis, design + assessment

Software Tour

Modelling with LUSAS

LUSAS Bridge has an easy to use, associative Modeller for modelling / results processing and a fully integrated Solver that can also be used independently.

Modelling features

  • The LUSAS user interface is a full native Windows implementation providing an Open Interface to ActiveX compliant Windows software such as Excel, Access, Word and other software.

  • Customisation of menus, toolbars and dialogs plus the ability to create your own wizards with Visual Basic Scripting provides limitless potential to tailor the software to specific needs.

  • Models are formed of layers where the visibility and properties of each layer can be controlled and accessed via the layer name held in a Layer treeview, one of a number of treeviews used to organise and access model data.

  • Models are created using feature-based geometry methods (points, lines, surfaces and  volumes). CAD import / export is supported. As the model is built up, model features may be grouped together and manipulated to speed up data preparation or to enable parts of the model to be temporarily hidden.

  • A model merge facility allows design teams to create separate models of specific parts of a structure and then combine them at a later date into one master model.

  • Model attributes such as thickness, material, loading, mesh/element type etc. can be named explicitly. Once defined they appear in an attributes treeview ready to be assigned to selected geometry of the model using the "drag and drop" technique.

  • Automatic meshing is provided with an easy-to-use mesh refinement capability.

  • Built-in associativity, a key feature of the LUSAS Modeller, ensures that if the model geometry is amended, all assigned loadings, supports, assigned mesh and other attributes are automatically updated to suit.

LUSAS Treeview

  • Fleshing (the visualisation of assigned thicknesses or section shapes) helps to ensure that the thicknesses and eccentricities of slabs and the orientation of beam members are correctly defined.

  • Datatips reveal useful model information such as assigned properties when the cursor is positioned on top of a geometry feature.

  • The OpenGL implementation provides fast graphical displays. Multiple graphical windows allow simultaneous displays of different parts of the model at different orientations. Powerful cursor selection options and pan, zoom, dynamic rotation and pre-defined views allow for easy viewing and editing of your model.

  • A multi-level undo/redo facility allows quick modelling corrections to be made.

  • Basic geometry data from third-party BIM/BrIM files (*.ifc) can be imported to create a feature-based geometry model in LUSAS. Both BIM/BrIM Structural domain files (*.ifc) and BIM/BrIM Architectural domain files (*.ifc) are supported for export.

  • Detailed on-line dialog help links to additional reference manual material to provide you with the most appropriate level of assistance at all times.


LUSAS wizards allow for quick and easy modelling, generation of loading conditions, and viewing of results. 

Steel Composite Bridge Wizard

Use the Steel Composite Bridge Wizard for quick and easy generation of the model geometry and corresponding mesh, geometric, material, support and local coordinate attributes for slab-on-beam composite I-girder bridges. Define models that accommodate:

  • Straight or curved decks of constant radius.
  • An arbitrary skew, where a skew can additionally be set per support and interpolated across the spans.
  • Any number of spans and supports.
  • Square and skew bracing.
  • Transverse stiffeners.
  • Design utilities for design checking against supported design code

Use the wizard to:
Define girder sections

Define cross-sectional information for a composite girder and slab (without upstands) for all required locations on the structure. 

Visualise the section being built in real-time as slab, top flange, web, and bottom flange dimensional data is entered.

Once defined, the composite I-Girder sections are used to define Girders.

Define girders

Define positions along the nominal bridge centreline at which pre-defined or newly created slab and girder cross-sections apply for a girder.

The length(s) over which section assignments are made for girders either side of the control centreline is calculated by the bridge wizard. 

Once defined, the girder components are used to define spans.

Define spans

Define the girders present in each span along with any bracing runs that occur between girders. Girders with offset slabs may be mirrored to create symmetrical arrangements.

Once defined, spans are used to define a bridge model as a whole.

Define supports

Define supports for the girders that are present in each span along with any bracing that occurs between girders at these supports. 

Skew can be defined uniquely for each support, and independently at that support for any defined support bracing. 

Once defined, the supports are used in the definition of the bridge model as a whole.

Define whole bridge

Define the type of bridge (straight or curved) to be generated along with a minimum mesh size.

Spans defining the bridge are selected (or defined) along with stating a length over which they apply. An option to reverse a span is also provided. Supports at the end of each span also need to be stated.

Once defined, the model can be automatically generated by the wizard.

Additional information relating to transverse stiffeners, bracing assemblies and intermediate bracing runs may also be specified either during the use of the wizard, or afterwards to update the initially created model.

Watch how to use the composite deck wizard


Grillage wizard 

Rapidly generate a wide variety of orthogonal, skewed and curved multi-span grillage arrangements. Cracked sections can also be included.

grillage_sequence.gif (36022 bytes)

Watch how to model grillages using the grillage wizard


Other wizards 

  • Other wizards include those for the calculation of critical road and rail loading configurations, design combinations, and dynamic pedestrian loading, along with loadcase generators for moving vehicle and train loads across a model.
  • Animation, graphing and print results wizards take users through the processes required to display results.

Section libraries and section property calculators

Section libraries and a range of section property calculators help to provide for straightforward modelling of grid/grillage and beam models.

Standard Steel Section Libraries

Access a range of steel sections from libraries including those for:

  • United Kingdom

  • United States of America

  • European Union

  • Korea

  • Australia

  • Canada

  • China

  • New Zealand

  • India

Precast Beam Section Generators

Use the precast beam section generator to calculate section properties of a range of country-specific precast concrete beams including:

  • United Kingdom Y, YE, TY, TYE, SY, M, UM, and U beam types

  • US AASHTO Type II to VI beams, Florida Bulb T beams

  • Canadian NU Girders. 

An option for including the contribution from a slab is provided so that the section properties required in a grillage model can be obtained.

Bridge deck grillage attributes

Define Bridge Deck (Grillage) geometric attributes that define geometric properties of specific types of bridge decks for analysing with reference to, or derived from grillage formulae published by Hambly and others. 

When assigned to a model along with a Bridge Deck (Grillage) material attribute, which contains separate material definitions for the slab, girders, slab and reinforcement (for cracked sections), the different phases of construction of these types of bridge decks can be analysed using a single model by the use of the multiple analysis facility. 

Standard section property calculators

Calcuate section properties for common section shapes such as rectangular, circular, I-shape, T-shape, L-shape, T-Shape and Z-shape sections.

Riveted and welded sections

These include: riveted I-section, T-shape, box, trough and cruciform sections, riveted boxes from I sections / channels, I-section with channel, or doubler plates, and welded plate boxes.

Arbitrary section property calculator

Use the arbitrary section property calculator to calculate section property data for any drawn shape or collection of section shapes.

For thin box sections, only the points and lines that define the centrelines of the plated members, and the geometric thickness of each line need to be initially defined for section property calculation to take place.

Compound section property calculator

Define compound sections from existing library sections. These can be positioned relative to each other and can have differing material properties assigned.

Infilled/ Encased Sections

Calculate section property data for the following infill/encased section types:

  • Filled box
  • Filled stiffened box
  • Filled pipe
  • Filled stiffened pipe
  • Encased hollow box - with rectangular or circular encasement
  • Encased filled box - with rectangular or circular encasement
  • Encased hollow pipe - with rectangular or circular encasement
  • Encased filled pipe - with rectangular or circular encasement
  • Encased I-beam - with rectangular or circular encasement
  • Encased Cross I-beam - with rectangular or circular encasement
  • Encased Combined-T-beam - with rectangular or circular encasement

Arbitrary section property calculator

Calculate section property data for any drawn shape or collection of section shapes.

Single and Multi-Cell Pre-cast Box Section Property Calculator

Calculate section properties of a single or multiple box cross section (with and without voids) from user defined dimensional data. The section shapes can be defined either as a simple cross-section or as complex section created from as many lines as are required to form a suitable representation of the true cross-sectional shape.

Single simple box section with void Multiple complex box section with void

Tapering beams and multiple varying sections

  • Define tapering beams by specifying section properties for each end.

  • Define multiple varying sections along a path of lines to easily build models of bridges having curved soffits, or arch structures having varying cross-sectional thicknesses.

Definition of a linear tapering beam Definition of a multiple varying section

Use of the tapering beam and multiple varying section facilities enables simple prototype and detailed staged construction models of bridges formed of tapered box sections to be created in a very straightforward manner.

Preliminary prepartion of a staged construction model

Library browser

Use the library browser to transfer attribute data, such as mesh, geometric, material, etc., between models.

Advanced elements, materials and solvers

Find out more

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Software Information

  Bridge / Bridge plus
green_arrow.gif (94 bytes) Software overview
green_arrow.gif (94 bytes) Modelling in general
green_arrow.gif (94 bytes) Advanced elements, materials and solvers
green_arrow.gif (94 bytes) Load types and combinations
green_arrow.gif (94 bytes) Staged construction modelling
green_arrow.gif (94 bytes) Geotechnical / Soil-structure modelling
green_arrow.gif (94 bytes) Analysis and design
green_arrow.gif (94 bytes) Design code facilities
green_arrow.gif (94 bytes) Viewing results
green_arrow.gif (94 bytes) Software customisation

  Bridge LT
green_arrow.gif (94 bytes) Software overview

  Choosing software
green_arrow.gif (94 bytes) Software products
green_arrow.gif (94 bytes) LUSAS Bridge LT
green_arrow.gif (94 bytes) LUSAS Bridge
green_arrow.gif (94 bytes) LUSAS Bridge Plus
green_arrow.gif (94 bytes) Software selection
green_arrow.gif (94 bytes) Software options

green_arrow.gif (94 bytes) Videos
green_arrow.gif (94 bytes) Case studies

  Application areas
green_arrow.gif (94 bytes) Footbridge design
green_arrow.gif (94 bytes) Movable structures
green_arrow.gif (94 bytes) Rail solutions
green_arrow.gif (94 bytes) Arch bridges
green_arrow.gif (94 bytes) Major crossings
green_arrow.gif (94 bytes) Soil-Structure Interaction Modelling

  Additional information
green_arrow.gif (94 bytes) Linear and nonlinear buckling analysis
green_arrow.gif (94 bytes) Curved girder analysis
green_arrow.gif (94 bytes) Integral or jointless bridges
green_arrow.gif (94 bytes) Post-tensioning
green_arrow.gif (94 bytes) Concrete modelling
green_arrow.gif (94 bytes) Interactive Modal Dynamics
green_arrow.gif (94 bytes) LUSAS Programmable Interface (LPI)

  General information
green_arrow.gif (94 bytes) Hardware specification
green_arrow.gif (94 bytes) Licencing and Networking options
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green_arrow.gif (94 bytes) Documentation
green_arrow.gif (94 bytes) Links page

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LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2022. Last modified: March 09, 2023 . Privacy policy. 
Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.