Bridge analysis, design + assessment

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Load types and combinations

LUSAS Bridge provides a comprehensive range of general loading types to cater for most circumstances. Vehicle load types, train loading, and prestress and post tensioning to many international design codes are also provided. Vehicle load optimisation facilities help find onerous traffic patterns. Envelopes, basic and smart load combination facilities help investigate maximum and minimum primary and coincident effects.

General loads

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.
  • Apply structural loadings that include gravity, concentrated, distributed, face, temperature, stress/strain, and beam loads.
  • 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 certain 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.

Vehicle loading

Vehicle loading facilities in LUSAS Bridge software make the generation of live loads very straightforward, significantly speeding up the task of defining the loading on a bridge deck. They comprise:

  • Static vehicle loading

  • Train loading

  • Load trains

  • Abnormal loading

  • Moving load generators

  • Vehicle load optimisation

Static vehicle loading

Static vehicle, lane, and knife edge loading types are provided for many international bridge design codes. These currently include: 

  • AUSTROADS Bridge Design Code HB77.2, AS 5100.2-2004, AS 5100.7-2004. (Australia)

  • Canadian Highway Bridge Design Code (CHBDC.)

  • JTG D60-2004 General Code for Design of Highway Bridges and Culverts. Peoples Republic of China)

  • Special vehicles defined as Load Model 3 (LM3) in the Danish National Annex to EN1991-2 (Denmark)

  • EN1991-2:2003 Eurocode 1: (Eurocode) including any country-specific load models as part of a country's National Annex to the code.

  • TIEL 2172072-99 and the National Annex EN1991-2 (Finland)

  • IRC:6-2000 Section: II Loads and Stresses. (India)

  • Israeli loading design code.

  • Korean loading code

  • NATO vehicle loading defined in annex A of STANAG 2021

  • New Zealand loading code

  • Norwegian loading design code

  • Poland loading code

  • TMH7 Code of Practice for the Design of Bridges and Culverts

  • BRO Classification loads (Sweden

  • BS5400, BD37/88, BD37/01, BD21/97, BD21/01, BD 86/11 and EN1991-2 National Annex 2.16 (United Kingdom)

  • AASHTO LFD and LFRD loading, and selected state dependent design loading

  • Additional loading types are being added all the time.


LFD & LRFD Static Vehicle Loading types

Train loading

Train loading options for many international bridge design codes including AASHTO and Eurocode are provided.

Load trains

  • Load trains can be created using a compound load facility.

Abnormal loading

  • Abnormal load generators are included.

Moving load generators

  • Static vehicle and train loadings can be used either on their own or with a moving load generator to automatically create the required set of loadcases as a loading type makes its way across a bridge.

Vehicle Load Optimisation

Significant amounts of time can be saved with the Vehicle Load Optimisation software option, which automatically generates the most adverse live load patterns for multiple lanes of vehicle (road) traffic, or tracks carrying train (rail) loading, in accordance with a variety of international design codes. The input of a few parameters enables an optimised load pattern to be generated for shell/plate element models and line beam models (vehicle loading only).

Vehicle load optimisation
Rail load optimisation

Vehicle load optimisation reduces the amount of time spent generating loadcases to replicate live loading on models, and leads to more efficient and economic design, assessment or load rating of bridge structures. 

For more details see Software Option - Vehicle Load Optimisation

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)

Envelopes and combinations

A key feature of LUSAS Bridge is the Basic, Smart and Code-specific load combination facilities which 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 and load factors.

  • Envelopes of multiple loadcases create maximum and minimum results.

  • The Smart Combinations facility automatically generates maximum and minimum load combinations from the applied loadings to take account of adverse and relieving effects. This enables the number of combinations and envelopes required to model a bridge to be substantially reduced. Absolute maximum envelopes are included.

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

Staged construction modelling

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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
green_arrow.gif (94 bytes) Software prices
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.