The Structural Engineering and Geomechanics group at Stanford University has had a long tradition in the area of risk and reliability analysis for hazard mitigation. Structural reliability concepts were conceived at Stanford, bringing prominence to the field and the Structural Engineering and Geomechanics group over the past three decades. During that time period, the field has matured and broadened to include problems ranging from the modeling of hazardous natural phenomena, such as earthquakes and hurricanes, to the evaluation of the performance of structures including buildings, dams, bridges and offshore platforms, to the assessment of the socio-economic consequences of such catastrophic events.

Seismic Hazard Assessment

The John A. Blume Earthquake Engineering Center has focused on seismic hazard assessment for over 25 years. Early work included the modeling earthquake sources and occurrence and the development of attenuation laws. In recent years, considerable effort has been put into
introducing mechanistic models into occurrence and attenuation phenomena. Stanford University researchers were responsible for developing probabilistic hazard analysis methodologies, using Poisson models and Bayesian models, and in incorporating fault rupture models in the overall algorithms. Stochastic time and slip predictable models have also been introduced in recent years. Finally, geographic information systems are currently under development to assist the user in processing vast amounts of geological, seismological and engineering information bases to estimate the seismic hazard for a site or a region.

Component and System Reliability

The need for safe operation of industrial facilities, such as nuclear power plants and manufacturing facilities that utilize hazardous materials, has led to the development of analytical methods for safety and reliability assessment of the structures and equipment at such facilities. Furthermore, uncertainties inherent in load processes, structural material properties, and design, as well as a lack of complete control of the construction process, have necessitated the development of design codes that quantify the various sources of uncertainty and randomness. Stanford University researchers were involved in the early development of structural reliability methods for components and systems safety analysis and continue to make advances in this field. Current research thrusts include the development of efficient methods of systems reliability for large systems, reliability analysis of components under time-varying loads, and the treatment of the nonlinear behavior of structural components under extreme loading conditions.

Challenges and Opportunities

Many current trends present challenges and opportunities to the field of risk and reliability analysis. At the narrowest level, structural engineering practice is beginning to adopt explicit probabilistic bases for the design of conventional facilities (e.g., new performance-based design seismic criteria that consider a range of damage levels and their likelihoods), and to demand improvements to them (e.g., better calibration to historic damage experience). Industries and regulatory bodies that are engaged in large special projects have moved steadily towards probabilistic structural analysis. The insurance industry has recently recognized that only formal probabilistic analysis of hazards, structural response, damage, and losses provides the potential for accurate forecasts of the likelihoods of rare catastrophic losses. Finally, the political arena is replete with activities that involve risk assessments of structures. These movements demand that structural reliability and risk analysis be made more accurate, broader, and more responsive to a wider set of interested parties.