Abstract
The basic seismic load parameters for the upcoming national design regulation for DIN EN 1998-1/NA result from the reassessment of the seismic hazard supported by the German Institution for Civil Engineering (DIBt). This 2016 version of the national seismic hazard assessment for Germany is based on a comprehensive involvement of all accessible uncertainties in models and parameters and includes the provision of a rational framework for integrating ranges of epistemic uncertainties and aleatory variabilities in a comprehensive and transparent way. The developed seismic hazard model incorporates significant improvements over previous versions. It is based on updated and extended databases, it includes robust methods to evolve sets of models representing epistemic uncertainties, and a selection of the latest generation of ground motion prediction equations. The new earthquake model is presented here, which consists of a logic tree with 4040 end branches and essential innovations employed for a realistic approach. The output specifications were designed according to the user oriented needs as suggested by two review teams supervising the entire project. Seismic load parameters, for rock conditions of v_{S30} = 800 m/s, are calculated for three hazard levels (10, 5 and 2% probability of occurrence or exceedance within 50 years) and delivered in the form of uniform hazard spectra, within the spectral period range 0.02–3 s, and seismic hazard maps for peak ground acceleration, spectral response accelerations and for macroseismic intensities. Results are supplied as the mean, the median and the 84th percentile. A broad analysis of resulting uncertainties of calculated seismic load parameters is included. The stability of the hazard maps with respect to previous versions and the cross-border comparison is emphasized.
Highlights
Probabilistic seismic hazard assessments (PSHA) represent the most resilient means to calculate seismic load parameters for seismic building codes or other anti-seismic design provisions, presupposing that the input models are carefully chosen and related parameters accurately derived
The hazard calculations were accomplished for rock underground conditions, characterized by an average shear wave velocity of the upper 30 m vS30 = 800 m/s for the hazard levels of occurrence, or exceedance probabilities, of 10, 5 and 2% within 50 years, which correspond to the mean return periods RP = 475, 975 and 2475 years
The hazard calculations were performed at nodes with a spacing of 0.1 times 0.1 geographic degrees, which corresponds to a grid of about 7 times 11 km in the middle part of the target area
Summary
Probabilistic seismic hazard assessments (PSHA) represent the most resilient means to calculate seismic load parameters for seismic building codes or other anti-seismic design provisions, presupposing that the input models are carefully chosen and related parameters accurately derived. These web-based seismic hazard results are used intensively for a wide variety of applications, for safety assessments of dams or other hydraulic structures The latter approach included epistemic uncertainties and aleatory variabilities of input parameters and models already to a considerable extent. All results, including the maps and, in particular, the UHS with the corresponding Eurocode 8 related control parameters, are accessible for the three hazard levels via a web-portal for any site within the target area Germany. This requires the usage of corresponding SSZ
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