Seismic design for the Confederation Bridge

This paper discusses earthquake loading in the design of the Confederation Bridge. The existing limit states design method requirements and the standard National Building Code of Canada earthquake are discussed. New relationships linking the probability of exceedance of the factored earthquake to the probability of exceedance of the unfactored earthquake, and linking the probability of exceedance of the factored earthquake to the notional probability for the safety index, are discussed. The response spectrum is constructed for a design earthquake that can occur in the 100-year design life of the bridge with a probability consistent with a safety index of 4.0. This response spectrum is used in the analysis of the Confederation Bridge structure. It is shown that the critical load combination for the design is not influenced by the earthquake loading.