Deaggregation of seismic safety in the design of the reinforced concrete building

Design of earthquake-resistant buildings according to Eurocode 8 is not based on the concept of\ud acceptable probability of failure since standard introduces fundamental non-collapse and damage\ud limitation requirements, which are associated with the design seismic action. It is foreseen that the\ud non-collapse requirement is satisfied when the regular buildings are designed to withstand design\ud earthquake, which corresponds to a return period of 475 years and thus to probability of occurrence of\ud 10 % in 50 years. Therefore, it is obvious that structures, which would be designed strictly according\ud to the fundamental non-collapse requirement of the standard, would be unacceptable for society. Due\ud to design safety factors it appears that structures withstand much stronger earthquakes in comparison\ud to the design earthquake. In order to assess whether the safety in design is sufficient and which factors\ud have the greatest impact on it, an eight-storey reinforced concrete building is investigated in the thesis.\ud The strength and system ductility of the six variants of the structure were evaluated on the basis of the\ud pushover analysis, wherein the requirements of Eurocode 2 and 8 were gradually taking into account\ud and the design assumptions were gradually excluded. Safety in design of the building was evaluated\ud by the difference between the calculated and prescribed behavior factor, the ratio between the design\ud and the near-collapse ground acceleration, which was assessed using the N2 method, and by the\ud escalation of the safety in terms of probability of exceedance of the near collapse limit state. It is\ud shown that the calculated behavior factor for the investigated building is 75 % higher than that\ud prescribed by Eurocode 8. This is reflected by the near-collapse ground acceleration. However,\ud questions arises whether the seismic risk of so designed building is acceptable, since estimated\ud probability of exceedance of near collapse limit state is 8.5·10-4, which is significantly higher than the\ud target reliability associated with other actions as prescribed by Eurocode 0