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Practice-oriented seismic response analysis for risk-based decision making

A so-called 3R method for checking the adequacy of seismic collapse risk, which represents realization of the concept of intensity-based assessment for risk-based decision making, is presented. The 3R method is not meant to be used for precise assessment of the collapse risk, but to make a decision as to whether the collapse risk of a new or existing building is smaller or greater in comparison with the target collapse risk. A clear decision model for risk acceptability was introduced for this purpose. The structural engineer can accept the design of a new structure or the strengthening of an existing one if collapse is observed in the case of fewer than half of the characteristic ground motions, which represent a subset of ground motions from the hazard-consistent set. All ground motions are scaled to characteristic target intensity which corresponds to target collapse risk and assumed value of dispersion of collapse intensities in log domain.

In this paper the fundamentals of the proposed method, including the motivation and terminology, are first summarized. This explanation is then followed by the step-by-step algorithm of the method and brief description of the theoretical background of the method. In the last part of the paper the method is demonstrated by checking the adequacy of seismic collapse risk for selected multi-storey building. It is shown that the risk-based decision can be sufficiently accurate by performing response analysis for only seven characteristic ground motions.

Author(s):

Matjaz Dolsek    
Faculty of Civil and Geodetic Engineering, University of Ljubljana
Slovenia

Marko Brozovic    
Faculty of Civil and Geodetic Engineering, University of Ljubljana
Slovenia