Benefits of vertically distributed isolation devices for an 8-storey structure with complex geometry

The construction of structures with curved or irregular geometry is becoming increasingly common as modern architects strive to create iconic buildings. However, the realisation of complex building forms creates significant challenges for structural engineers in regions of high seismicity. If a structure possesses an unusual geometrical form, this introduces significant uncertainties in the likely plastic mechanism, with questions on the likely performance of connections and doubts about the probable loadpaths. This paper examines the benefits of a novel seismic isolation strategy that could be particularly adept to structures with complex geometry. The seismic design strategy proposes the use of isolation devices distributed vertically up a building between the exterior structure (of complex-geometry) and the heavy internal core. An innovative Direct DBD methodology is used to design an 8-storey case study building in which visco-elastic devices are used to isolate a steel diagrid structure via the innovative isolation strategy. Non-linear time-history (NLTH) analyses are then conducted on a 3-dimensional model of the building using a suite of real accelerogram pairs, scaled uniformly to be spectrum compatible. The results of the NLTH analyses indicate that the target displacement and drifts for both the internal and external structures are well controlled by the design solution. Furthermore, the results generally indicate that the vertically distributed isolation system could be a very effective means of controlling the seismic response of structures with complex geometry.