RAPID: Evaluation of Analytical Assessment Tools through Comparisons to Observed Seismic Performance in the January 2010 Haiti Earthquake

University Of Arizona, Tucson AZ

Investigators

Abstract

The magnitude 7.0 January 12, 2010, Haitian earthquake severely damaged several modern engineered buildings in the capital city of Port-au-Prince. This research project will gather perishable data on the observed performance of these structures for the purposes of comparison with, and calibration of, analytically-based response predictions used in seismic assessment procedures. The research is a partnership between academia and industry with university researchers working alongside professionals from the earthquake engineering consultant firm, Rutherford and Chekene. The project relies on close collaboration with a faculty member at the Université de Sherbrooke, Canada, who has established contacts and first-hand knowledge of the conditions on the ground in Haiti. The objectives of the research are to: (1) catalog and classify damage for a class of structures in the Haiti earthquake; (2) correlate damage to structural system, layout, design and detailing; and, (3) evaluate the efficacy of analytical techniques and procedures used in current assessment. The expected research outcome is a report documenting: (1) structure/site description; (2) design information; (3) documentation of post-earthquake state; (4) description of analytical techniques and model; (5) analytical results and comparisons; and (6) evaluation of the methods. The research will involve the documentation of the design, site conditions, and observed damage on a small set of important engineered structures (schools, institutes, government buildings), focusing on reinforced concrete construction. Candidate structures have been identified, all within the capital city of Port-au-Prince, on the basis of damage state, available design information, and accessibility. Seismic performance of the candidate structures will be obtained primarily from on-site visual inspection in Haiti by the research team and collaborators. Included in the inspection will be failure modes, damage intensity and patterns, and residual state. The available information will be used to construct analytical models using state-of-the-art techniques for nonlinear dynamic analysis. Seismic hazard levels will be estimated by indexing to the level of demand required to bring about the observed damage. In this process, the analytical models will be subjected to incremental dynamic analysis in order to map the observed damage to reference amplitudes available from USGS shake maps. Then, predictions of the observed response can be conducted using accepted seismic assessment techniques common in the U.S. (linear, nonlinear, static, and dynamic) and compared to the observed actual performance. In particular, the effectiveness of the structural models to produce similar behavior modes, overall patterns of damage, and appropriate assessment decisions will be evaluated. Conclusions on the efficacy of these methods will be drawn through comparisons of the predicted response to actual outcomes. Preliminary evaluation of the sensitivity of the response to various parameters and model calibration will be performed. Where possible, the sensitivity of the predictions to different variables and estimations of uncertainty will be made. This work gathers perishable information on building performance in actual seismic events and has the potential of providing information on a key step in seismic assessment, namely calibration of models. This research additionally extends knowledge on seismic performance of reinforced concrete structures in earthquakes. The potential impact of this research is increased public safety and more informed decision making pertaining to infrastructure retrofit and upgrading through improved analytical models and assessment techniques, as well as improved retrofit evaluations. The information provided by this project can be used widely by earthquake engineering researchers. Project results will be made available to the profession through the industry partners' participation in professional groups and committees. Project investigators will also present results of the study at a workshop for Haitian earthquake RAPID awards in summer or fall of 2010.