Beijing National Stadium by Herzog and de Meuron: Though the arrangement of primary structural members is regular, the secondary and tertiary members are laid out randomly (see Figure 2b and c). Although they are structurally less important, they are also made up of the same 1.2 by 1.2 m steel box sections (however the thickness of plates of these sections varied between 10 mm to 100mm depending on the load carrying capacity). The secondary and tertiary members support the roof cladding and play a vital role in the seismic design. Even in a severe earthquake, the primary structure will remain elastic. The secondary and tertiary members, however, are designed to yield-thus minimizing the damage to main load- bearing members.