LUSAS

The new roof consists of a primary cable net structure supporting articulated steel trusses which create the upper roof profile and in turn support the roof coverings. The existing compression truss connections and raked V-columns required strengthening to bear the increased loading from the new roof structure which, at approximately 48,000 square metres, and with a maximum cantilevered length of 84m, is twice the area and three times the span of the original.

The construction sequence and hence modelling and analysis requirements for the new roof took place in three distinct phases:

• Phase 1: V-column strengthening / replacement
• Phase 2: Installation of cable net
• Phase 3: Construction of rear and front roof

LUSAS was required to verify the adequacy of the global structure and structural members at critical stages of construction. This involved:

• Ensuring that the starting LUSAS finite element model (used in a reverse analysis) satisfied the reference stressed state reflecting the permanent condition of the completed stadium roof.
• Analysing the staged replacement of the V-columns and providing an envelope of member forces on connections for use and verification of local connections by others.
• Analysing the roof structure at various stages in order to verify that all structural members designed for permanent condition were adequate for the proposed construction methodology and that structural stability was maintained throughout.
• Providing internal forces, enveloped erection force effects and utilisation factors for critical members in the roof members, cables, compression truss and column structure for various stages of the construction process; and displacements at key locations for various stages.