NEESR: Next Generation Dissipation Guidelines for New and Existing Structures using the NEES Database

Northeastern University, Boston MA

Investigators

Abstract

The research objective of this award is to characterize energy dissipation capacity not associated with damage in buildings subjected to earthquakes. The project takes a multi-prong approach to attain this objective. On the analytical side, it examines how identified equivalent damping is affected by excitation frequency content (since the actual mechanism is unlikely viscous) and how sampling rate and the free parameters of various identification algorithms affect the computed imaginary part of the poles, which determines the equivalent damping. Because the effort is on identifying dissipation associated with non-damaging mechanisms, the project looks at data-driven means to classify observed responses as being quasi-linear or notably non-linear. The project includes development of a procedure, based on the classical tracking problem from control theory, to separate the non-damaging dissipation from the total dissipation. The database from the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Project Warehouse is used to validate the analytical studies and, complemented with data measured in buildings in the field, is used to formulate guidelines for specifying damping ratios for new and existing structures. Data from this project will be archived and made available to the public through the NEES Project Warehouse data repository at http://www.nees.org. The project is part of efforts to devise efficient means to provide structural designs that not only provide life protection for large earthquakes but also minimize economic losses associated with exposure to seismic events of all sizes. Although computational capability and modeling of elastic and inelastic behavior, including cyclic response, has improved notably in the past few decades, little change has taken place since the 1960's on criteria for the specification of non-damaging related dissipation, which plays an important role for predicting response for small and moderate events. This project leverages data that is currently available in the NEES Project Warehouse data repository to constrain analytical research on the question of non-damage related dissipation in seismic engineering. This award includes an educational outreach initiative that integrates the research with education for undergraduate and high school students. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).