SGER: A Feasibility Study of Estimation of Structural Systems Reliability Under Hurricane Hazard

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

PI: Rajagopalan Balaji; University of Colorado The assessment and prediction of structural system reliability in the face of hurricanes are of great interest to our nation. Several public and private planning and disaster management agencies need such information for developmental planning and disaster mitigation strategies. Also, insurance agencies are interested in the structural reliability estimates to evaluate and set premium levels. Models for structural risk and reliability exist in the private sector but they are not public domain, and often they are adhoc in nature. Furthermore, these models evaluate structural reliability in isolation of realistic likelihood estimates of hurricane frequencies, magnitudes and their associated characteristics (such as winds, precipitation and floods). Thus, there is a real need for the development of an integrative framework that has a realistic hurricane track simulation model coupled with a structural risk/reliability model, to generate static (long term) and dynamic (time varying) structural risks and also the capability to classify structures as per their reliability. Objectives of the study With the need for a comprehensive and integrated framework as the motivation, the aim of the proposed study is to demonstrate the feasibility of the integrative framework. To this end the objectives are: 1. Use the historical hurricane track data to compute probabilities of occurrences of .events at any desired location (events are defined by threshold exceedence of wind speed and precipitation, as wind speed are the key loading factors on structures). Also estimate these probabilities conditioned on climate indications [e.g., El-Nino Southern Oscillation, North Atlantic Oscillation etc.]. 2. To develop structural load probabilities on different class of structures (e.g., timber, masonary, concrete etc.) based on .event. probabilities developed from above. 3. To develop structural reliability estimates (both stationary and time varying) conditioned upon the load probabilities. These outcomes will help us in implementing this framework with hurricane track simulation models. Intellectual Merit This proposal attempts to develop cross-disciplinary framework for structural risk/reliability assessment in the face of hurricanes. The approach is unique in that it brings together the knowledge of (a) Atlantic hurricane variability (both in terms of the number of hurricanes and the tracks); (b) Estimating probabilities of associated components (precipitation, winds, flooding etc.) using nonparametric functional estimation techniques, (c) probabilistic structural load estimation, and (d) Bayesian techniques for structural risk/reliability assessment to develop long term and time varying risk estimates. This unique and integrative approach to a practical problem is the main intellectual merit of this proposal. Broader Impacts The outcomes from this study will significantly help in developing applying this framework in conjunction with a stochastic hurricane track simulation model, for the entire US coast and for different structural groups. This will also supplement the HAZUS initiative by FEMA for enhancing the nation.s risk assessment capabilities under natural hazards. These outcomes will be extremely helpful for their contributions to the knowledge base and intellectual growth in the area of civil infrastructure assessment as well as the reduction of risks induced by hurricanes.