SYSTEMIC UNCERTAINTIES AND DECISION SUPPORT APPLICATIONS IN REGIONAL SEISMIC LOSS ANALYSES
A number of tools and advancements have been developed over the course of the last decade for public use in regional seismic disaster planning. This paper addresses some of the considerations and approaches that influence state-of-theart regional seismic loss assessments and risk management, with particular emphasis on approaches applied to areas having potentially high consequence but low probability seismic hazards in the United States. The various components of regional seismic loss assessment are synthesized within a GIS-based framework, including the aggregation and propagation of uncertainties inherent in the analysis. The threat posed by ground shaking and ground failure hazard effects is estimated and mapped onto high resolution point-wise building stock and bridge inventory assets. Inventory vulnerability is assigned based on structural classifications of construction materials, together with general system configurations and lateral resisting system types. Likelihood of damage to the built environment is then determined by the combination of the hazard and vulnerability for each building and bridge, and social and economic consequences are projected based on correlation with descriptions of physical damage levels, both in terms of expected values, and dispersions of the aggregate regional analysis output. Decision support algorithms are also discussed, which leverage the high resolution of the regional analysis output to focus mitigation planning and capital investment on particularly sensitive and influential assets within study regions.
Probabilistic fragility analysis parameterized by fundamental response quantities
Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.
The Lunar Rocks
Book on lunar rocks covering pre-Apollo lunar scientific knowledge, Apollo and future lunar mission planning, lunar mineralogy, petrology and geochemistry, etc