Building Reliability and Code Calibration

Designs of buildings and structures for seismic loads are traditionally based on experience on performance of structures in past earthquakes. The large variability in the earthquake loadings has long been recognized by engineers but not fully accounted for in the code procedures. Although the selection of the design earthquake is based on probability, since it is used in conjunction with a series of factors depending on structural period, site soil conditions, inelastic behavior, importance of the structure e.t.c., the reliability and safety of the final design remains unknown and undefined. The recent sentiment of the research community and design professionals is that there is a need to develop design formats based more on consideration of the physics of the problem and explicit treatment of the variabilities and uncertainties. Such format may be used as the basis for developing future building codes. This paper summarizes some recent developments in this area; in particular, reliability evaluation and comparison of buildings designed in accordance with current code procedures in different countries and development of design procedures and formats based on multi-level, probabilistic structural performance criteria.