| Popis: |
The deformation characteristics and the dynamic amplification of the response of a building subjected to an earthquake can be estimated from the dy- namic characteristics of the structure. In the present study, the fundamental nat- ural frequency of a structure, a key factor influencing the damage after earth- quakes, is examined. The investigated structure is the building of the National Institute of Geophysics, Geodesy and Geography (NIGGG), to the Bulgarian Academy of Sciences, which is a five-floor, cast-in-situ reinforced concrete (RC) building. The campus area adjacent to the building was also studied. Two in- dexes, related to the performance during earthquake were calculated using ambi- ent vibration data; (i) the vulnerability index of the studied structure (Kb), and (ii) the coefficient of vulnerability of ground of the adjacent free field (Kg). The vul- nerability index was calculated at ten locations on each floor. The maximum value computed in the present study was 81, indicating the location where the structure experiences the highest dynamic amplification and is hence the weakest and most likely to fail first during earthquake. The maximum possible interstorey drift ratio due to a design earthquake peak ground acceleration (PGA) was also determined. All measurements were performed using four ETNA 2 mobile accel- erometers with a recording frequency of 100 samples/second, and recording time at each point 20 minutes. |
