Seismische Tragfähigkeit eines Stahlbetongebäudes

Seismic robustness of a reinforced concrete structure

Seismology and earthquake engineering have experienced major progress in the last decades. This progress is implemented in current modern codes of practice for the design of new structures. However for existing structures, mainly designed according to former codes of practice, a realistic estimation of the seismic robustness and ultimate load is also necessary. Often in such cases ambitious analyses are carried out. This paper describes the steps of such an analysis for a reinforced concrete structure, which is part of the critical infrastructure. In a first step the nonlinear force-deformation-curve is investigated by a pushover-curve. This curve is applied to an equivalent oscillator. Further dynamic properties of the oscillator are obtained from a soil-structure-interaction analysis. The oscillator is then exposed to various time-acceleration-sequences. This computation yields to a ductility demand. The ductility demand can be related to different earthquake intensities by scaling the time-acceleration-sequences. Finally the investigation was carried out twice, using characteristic and mean material properties. An overall deviation of the structural resistance can be provided by these parallel computations in combination with the deviation of the various time-acceleration-sequences. The results are used to construct a fragility curve and hence the ultimate seismic load bearing capacity.