# Base Isolation Compared to Capacity Design for Long Corner Periods and Pulse-Type Seismic Records
## 4 Discussion  
Base isolation is an effective structural solution in contrast to the \"stiffening\" design approach, even under special seismic conditions characterised by long predominant periods and pulse-type seismic ground acceleration records.  
For the analysed building, a 45% drop of the floor acceleration at the top of the building was obtained by base isolation. This is likely to reduce the seismic damage of the acceleration sensitive components of the building. A total of 90% of the lateral displacement is concentrated in the isolation layer, protecting the upper structure from earthquake-induced damage in displacement sensitive components. A large reduction of the base shear force was observed as well.  
Drift values for the isolated structure are negligible and plan irregularity effects are corrected by the isolation level. Detailed information upon the influence of plan and elevation irregularity on the seismic response of the analysed hospital building are shown in [30]. The stiffened structure experiences instead large drift values, expected to endanger the nonstructural components of the building.  
The rigid body movement of the base-isolated structure is likely to inhibit any damage for the structural and nonstructural components of the building. This is of particular importance for the hospital buildings that are required to remain functional after the incidence of a strong earthquake.  
Pulse-type seismic records may force isolators to reach their displacement capacity. In this study, the maximum displacement at isolation level was 0.49 m according to the performed time history analysis. This maximum displacement value is reached only during one pulse and it exceeds the DBE design isolator displacement capacity of 0.392 m. Nevertheless, isolators were checked to also withstand an MCE earthquake, according to which they have a displacement capacity of 0.535 m.  
Curved sliders are sensitive to uplift for pulse-type seismic records. The analysed hospital building showed sufficient vertical loading such that the horizontal seismic action caused no uplift. All isolators remain functional even during the main shock.  
Supplementary to the evident structural advantages encountered for the base-isolated solution of the analysed hospital structure, an economical comparison (as-built state as well as life-cycle analysis) is planned to be performed.  
Conceptualization, D.K. and F.W.; methodology, D.K.; software, D.K.; validation, E.L., V.P. and F.W.; formal analysis, D.K.; investigation, D.K. and F.W.; resources, D.K.; data curation, D.K.; writing--original draft preparation, D.K.; writing--review and editing, F.W., E.L. and V.P.; supervision, F.W.; project administration, D.K.; funding acquisition, D.K. All authors have read and agreed to the published version of the manuscript.  
This research was funded by \"Stiftung Maurer Sohne\", Munich, Germany.  
Not applicable.  
Framework and reinforcement drawings for the analysed structure were kindly provided by S.C. Consild S.R.L, Bucharest, Romania.  
The authors declare no conflict of interest. The funder is represented by [PERSON] among the authors because he supported the study as follows: design of the curved slider isolators, technical data regarding the curved slider isolators, review of the manuscript.