## 4 Results
### Nonlinear Time-History Analysis  
The results obtained by time-history analysis, due to seismic loading for various intensities depending on the earthquake return periods, will be presented in the following text. Sets of acceleration records, obtained by two different approaches (Section 3.3), with a peak ground acceleration on the bedrock of 0.16 g for 95 year RP and 0.302 g for 475 year RP, were used in analysis. The prescribed requirements and limit states in Eurocode 8-3 [43] correspond to defined earthquake return periods. Although the records were generated also for the 2475 year RP, the analysis has shown that this level of earthquake intensity is too high for this building, so the results are not presented herein. Artificial records, matched in the frequency region to be compatible with the target response spectra, are labelled EC8, while the records representing the deterministic seismic hazard of the hospital location are labelled OBDD. Only the most significant results, comprising two sets of accelerograms per one return period, are presented, due to a large amount of obtained data. It is important to note that the presented results are representative for all time-history analyses performed at that particular earthquake intensity. Failure mechanisms and the behavior of critical structural elements will be qualitatively and quantitatively depicted. The base shear and horizontal displacements of the control point near the building top (at story nine) are presented as fundamental structural response parameters. In addition to the characteristic point, displacements of the point located at the same story, but on the opposite side of plan, are shown. By comparing displacement responses, torsional effect in the structural response may be observed. Furthermore, shear forces in critical structural elements are presented because it was confirmed that failure in most of the elements is induced by shear. Critical structural elements and control points (labels) at story five--the critical story for determining the structural seismic performance and the story where initial failures occur--are presented in Figure 20.  
Figure 20: Story 5: critical structural elements (labels). In the following figures, the representative results are presented for six earthquake scenarios, calculated using a set of accelerograms:  
* simulated for the location within the deterministic earthquake scenario of a 95 year RP with a PGA of 0.16 g (Figure 21);
* generated according to the Eurocode 8 spectrum for a 95 year RP with a PGA of 0.16 g (Figure 22);
* simulated for the location within the deterministic earthquake scenario of a 225 year RP with a PGA of 0.21 g (Figure 23);
* generated according to Eurocode 8 spectrum for a 225 year RP with a PGA of 0.21 g (Figure 24);
* simulated for the location within the deterministic earthquake scenario of a 475 year RP with a PGA of 0.30 g (Figure 25);
* generated according to Eurocode 8 spectrum for a 475 year RP with a PGA of 0.30g (Figure 26). These figures show: (a) displacements of ux and uy of points 3 and 54 at story nine in time; (b) the base shear in the X and Y directions in time; (c) and (d) the shear forces in time for critical structural elements at story five; optionally (e) time snapshots of the failure mechanisms' development at story five. In order to make the presentation of the results clearer, the diagrams show the first 10 s of the response in which the most significant part of the earthquake motion is realized. For the deterministic earthquake scenario (95 year RP), it may be observed that the largest displacements amount to 2.0 cm. The peak base shear is approximately 20,000 kN. Cracking and yielding of the critical elements occur, but the failure is not expected. For the earthquake scenario (95 year RP according to the Eurocode 8 spectrum), it may be observed that the largest displacements amount to 3.2 cm. The peak base shear is approximately 22,000 kN (disregarding one particular peak), which corresponds to the value obtained by the response spectrum analysis.