Engineering analysis and design software
Bridge design and engineering

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Staged construction modelling

Staged construction modelling is essential for many forms of bridge design and construction, whether it be for carrying out a detailed analysis of an incrementally launched segmentally constructed box girder bridge, modelling cable or hanger replacements for cable stayed and suspension bridges, or modelling a demolition process. 

LUSAS provides you with the means to model the construction, rebuilding or demolition of your structure over time, and evaluate the effects of structural changes, load applications, and any time-dependent material changes.

Construction sequence modelling for a single span of West 7th Street Bridge, Texas

The modelling process

A complete staged construction modelling process for a model is controlled in the Analyses panel of the LUSAS Treeview. When modelling, groups of elements and associated attributes can be activated and deactivated, with supports being carried forward between loadcases, introduced or removed to accurately represent each stage of construction. Construction history tables containing displacement history and incremental displacement results can be produced.

With LUSAS Bridge, unlike some software, only one model file need be created and this can contain all of the information required to carry out an analysis of every stage of construction. The effects of geometric and material nonlinearity, and time-dependent material effects such as creep and shrinkage can all be included.

Construction modelling of Paseo Bridge

The latter stages of the demolition modelling of Paseo Bridge


Staged construction with LUSAS

  • Model full staged construction with beams, shells and solid elements (some software only permits beams to be used)

  • Full activation and deactivation of elements is supported

  • Model any support condition and add or remove supports as required during the construction sequence

  • Sliding bearings may be modelled using nonlinear contact (slidelines)

  • Support and loading facilities including temporary/traveller loads

  • Apply loads anywhere onto any model

  • Change loading/stress/strain over time and lock- in stresses, if applicable, between stages

  • Prescribed displacements or jacking loads may be used as spans are completed

  • Time-dependent material properties include stress related concrete creep and shrinkage to CEB-FIP Model Code 1990, (and others) and includes creep recovery

  • Custom time-dependent curves for particular material properties and codes

  • Use single or multi-tendon wizards to define and assign tendon properties and time-stages to features of a model.

  • Steel relaxation, time effect on elastic modulus, tendon post-tensioning losses from creep, shrinkage, and superimposed loads

  • Cumulative effects can be reported separately for each loadcase, such as post-tensioning effects, or for the effects of just creep and shrinkage

  • Incremental effects can also be specified allowing you to view and assess the net changes to the structure since the previous stage.

Animation of axial forces in members during dismantling of the San Francisco-Oakland Bay Bridge East Main Span.


Use for

Use for all types of staged construction methods and bridge types including:

  • Staged placement of beams and slab for continuous structures

  • Cast insitu span-by-span construction of continuous beams

  • Precast segmental span-by-span erection

  • Cast insitu balanced cantilever construction

  • Precast segmental balanced cantilever construction

  • Progressive erection of precast segmental decks

  • Incremental launching

  • Balanced placement for cable-stayed bridges

  • Composite decks

  • Extradosed bridges

  • Suspension bridges


Span-by-span example

The erection of all segments for a span in a set, which is then aligned, jointed, and ultimately, usually, longitudinally post-tensioned together to make a complete span. In LUSAS, this can be modelled as a line beam model with optional fleshing of the deck cross-section to show results contours. 

The animation below shows the construction sequence for the twin rib span-by-span example shown (substructure not included). The analysis can incorporate post-tensioning  between stages, and creep effects as construction continues, as required.

Balanced cantilever

The building of a bridge superstructure from both sides of a pier in a scales-like fashion. 

Using LUSAS, creep / shrinkage analysis can incorporate an age attribute (for precast elements) and checks on robustness can also be made as, for example, where a segment may be inadvertantly dropped by crane and where dynamic effects (impulse) are important. 2nd order (P-delta) effects could also be included.

Incremental launching 

Incremental launching involves the casting of a continous chain of bridge segments on-site adjacent to the actual location of the bridge and then pushing the growing superstructure out over temporary and permanent supports at the bridge's location - as used in the construction of the Blackwater Viaduct in the Republic of Ireland.

Using LUSAS, incremental launching can be carried out for both in-line deck launching, or for a curved deck launch. Modelling of incremental launching can be done by activating and moving a series of supports backwards under a model that is incrementally being added to. This can be done via general modelling facilities, or by scripting methods to automate the modelling process.

Blackwater viaduct, UK. Photo: Benaim)

An example of this method for a box girder bridge with a simplified nose is shown below.

Curved deck launching

Click to play movie (in new window). 

Click to play movie (in new window)

Staged Construction Modelling : Case Study

The initial proposed I95 Mississippi River Bridge was designed to be a record-breaking, cable-stayed structure linking the States of Illinois and Missouri in the USA, helping to relieve traffic on existing bridges across the river. Designed by Modjeski & Masters for its clients Missouri and Illinois Departments of Transportation, staged construction facilities in LUSAS Bridge were used to model an 800 day construction period, followed by a 10000 day period to allow for creep over that length of time.

No movie provided for this yet

Geotechnical / Soil-structure interaction 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
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  Bridge LT
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  Videos
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  Choosing Software
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green_arrow.gif (94 bytes) LUSAS Bridge LT
green_arrow.gif (94 bytes) LUSAS Bridge
green_arrow.gif (94 bytes) LUSAS Bridge Plus
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  Software Options
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  Case Studies
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  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
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Any modelling and analysis capabilities described on this page are dependent upon the LUSAS software product and version in use.