Bridge analysis, design + assessment

Case Study

Initially Proposed Mississippi River Bridge

  • Proposed record-breaking cable stayed road bridge
  • Detailed advanced 3D nonlinear and dynamic analysis
  • Staged construction incorporating creep and post-tensioning

Mississippi River Crossing (Original Proposed Design)

If it had been built, the initial proposed New Mississippi River Bridge would have been a record-breaking, cable-stayed structure linking the States of Illinois and Missouri in the USA, helping to relieve traffic on other bridges across the river. The designer, Modjeski and Masters, was chosen by the Illinois and Missouri Departments of Transportation to perform both the bridge-type study and to provide preliminary and final design for the proposed crossing.

Facts and figures
  • At 222 feet (68m) in width, the Mississippi River Bridge would have been the world’s widest cable-stayed structure.
  • It was designed to carry eight traffic lanes with shoulders that provided for four additional lanes in the future.
  • The total length of the bridge was approximately 3,150 feet (961m).
  • The main span of 2,000 feet (610m) would have been the longest clear span across the Mississippi River, the longest cable-stayed span in the Western hemisphere and the fifth-longest cable-stayed span in the world.
  • Two 510 foot (155m) high single pylon towers soared 435 feet (133m) above the roadway.
  • It would have been the first major cable-stayed bridge to use three planes of cables in the main span.

Modjeski and Masters used LUSAS Bridge to assist with a number of global and local analyses of the structure because of the advanced 3D nonlinear, dynamics and staged construction facilities that it offers for this type of work.

Analyses with LUSAS Bridge included:

  • Static analysis under dead loads
  • Moving load analyses, including fatigue load determination
  • Nonlinear static stability analyses of the free-standing towers and of the completed bridge
  • Frequencies and mode shapes
  • Spectral earthquake analyses in 3D
  • Modelling of creep in the concrete towers during construction and in service to model code CEB-FIP90
  • Staged construction analysis of the deck erection sequence
  • Detailed analysis of forces in cellular concrete components 
  • Detailed analysis of steel plate stresses at connections and cable anchorages

Staged construction modelling

Following costings an alternative crossing solution was sought. 


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