Bridge analysis, design + assessment

Case Study

Approach viaduct design for the Vasco Da Gama bridge

  • reinforced concrete diaphragms

  • prestress analysis and seismic loading

  • reinforcement quantities calculated

Kvaerner Technology Ltd is one of a consortium of companies designing the New Tagus Crossing in Lisbon, Portugal. It used the extensive solid modelling capabilities of LUSAS Bridge for analysing reinforced concrete diaphragms on the 6.5km long central viaduct section of the crossing.

Each 77m long viaduct span unit consists of 8 precast box sections that are assembled, prestressed and concreted together before floating out and jacking into position onto piers initially on temporary supports. Once adjoining spans are in place, continuity prestress tendons are fixed through the diaphragm walls into adjacent units and a 1m wide 'working-room' gap between units is infilled with concrete to match web and flange thicknesses of adjoining units. A pair of 1m x 1m permanent bearings are installed directly under the infill concrete and all temporary supports are removed.

Three different diaphragm designs were required to cater for standard span units; special 'lay-by' units - with wider decks and with thicker walls; and for units with movement joints. Different LUSAS models were required for each diaphragm type in order to analyse the stresses due to deck loadings, anchorage forces from prestress and bearing reactions. Models of the end 6m of each span unit type were built using 8-node enhanced strain solid brick elements. Spring supports represented bearings and dead, supported, live, and seismic loadings all had to be considered.

LUSAS was used to analyse 3 stages of construction: Stage 1 prestress in the casting yard; Stage 2 prestress once the units are in final position with infill zones concreted; and Stage 3, to give bearing reactions under normal and seismic loading. A linear static analysis was completed for the various loadcases and, by use of the LUSAS slice section facility, moments and forces at critical sections through the webs and flanges of the diaphragms were easily obtained to allow the diaphragm reinforcement quantities to be calculated.

"This was the first time I had used LUSAS. I found it easy to use and by using the slice section facility we obtained a better understanding of the behaviour of the structure. This helped us to produce a detailed design which could not have been done easily using alternative simplified methods".

Walid Mahmoud, Senior Bridge Engineer, Kvaerner Technology Ltd 

Find out more

LUSAS Bridge

Software products

Software selection



Other LUSAS Bridge case studies:


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

Request information


innovative | flexible | trusted

LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2022. Last modified: March 07, 2023 . Privacy policy. 
Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.