Effect of Low-Cycle Fatigue on the Seismic Vulnerability of Aluminium and Steel Domes

The low-cycle fatigue resistance of a material can influence the seismic vulnerability of a structure. Aluminium alloys are generally more susceptible to failure under low-cycle fatigue compared to steel. However, aluminium is an effective solution for domes exposed to aggressive environments such as chemical storage facilities, domes covering large spaces such as stadiums and domes with structural members connected efficiently (e.g. Mero) using extruded aluminium profiles. This is due to the durability, the high strength-to-weight ratio and the extrudability of aluminium alloys. The vulnerability of aluminium domes under earthquake ground motions may be influenced by its cyclic mechanical properties, including low-cycle fatigue. The rupture of a member under low-cycle fatigue can be captured by considering the earthquake-induced plastic strain cycle in the member. In the present study, the seismic vulnerability of aluminium and steel domes under the same gravity load are compared by developing fragility functions based on incremental dynamic analyses. The results showed that the low-cycle fatigue resistance of the material has a significant influence on the seismic performance of the domes. The aluminium dome and the steel dome were able to sustain seismic loads with spectral accelerations at the fundamental period up to 2 g and 2.5 g, respectively. It was observed that the aluminium dome showed a good seismic resistance for practical intensities representative of the design spectrum of Vancouver, BC, Canada.