SGER: Large-Scale Validation of Seismic Performance of Bridge Columns

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The goals of this Small Grant for Exploratory Research (SGER) project are to: (1) provide the nucleus around which other investigators, practitioners, and funding agencies can participate; (2) actively collaborate in the planning of the E-Defense bridge column test program; (3) compile and distribute (in accordance with NEES Consortium, Inc., and E-Defense policies) data from the entire test series, including archival in the NEES data repository; (4) conduct a series of experiments on full-scale bridge columns detailed consistent with current U.S. design practices; (5) interpret these data in terms of other data from the E-Defense test program, as well as from previous reduced-scale tests in the United States; (6) carry out numerical simulations using advanced physics-based models as well as simpler phenomenological models of the type used in design practice; (7) evaluate current design and analysis practices in view of these tests and analyses; and (8) widely disseminate results.Major transportation structures, such as bridges, have suffered tremendous damage in recent earthquakes, as observed during the 1989 Loma Prieta, 1994 Northridge, 1995 Hyogo-Ken Nanbu, Japan, and 2001 Nisqually earthquakes. Such damage limits the ability of the affected community to conduct emergency response operations, slows recovery, and strains the limited resources available for post-event reconstruction and development. Many have conjectured that such damage could have been avoided had large-scale seismic tests been done on bridges prior to these earthquakes. Fortunately, considerable experimental data has become available during the past two decades to help improve design, evaluation, and retrofit methods based on quasi-static, pseudo-dynamic and dynamic tests of bridge components. However, these dynamic tests of bridge columns have all been conducted using substantially reduced (one-tenth to one-quarter) scale specimens. Because many important modes of behavior (shear, anchorage, and fracture) do not reproduce well in reduced scale models, the earthquake engineering community has placed high priority on carrying out realistic, full-scale shaking table tests of bridge columns. The recent construction of the Earth Defense (E-Defense) shake table at the Hyogo Earthquake Engineering Research Center in Miki, Japan makes such experiments now feasible. Japanese researchers are moving ahead rapidly to conduct research on full-scale bridge columns and systems using the E-Defense facility. During 2007 and 2008, they will use E-Defense to conduct a series of experiments on approximately seven full-scale reinforced concrete bridge columns representative of past and current Japanese design and construction practices. While these tests will provide fundamental data on the dynamic behavior of full-scale columns, the usefulness of this data by itself to the U.S. engineering community is not optimal.This project responds to an exceptional immediate opportunity for U.S. researchers, practitioners, and students to participate in the planning, conduct, analysis and interpretation of these experiments. Planning in Japan is well advanced, and significant resources are being mobilized to carry out the tests. The strong U.S. collaboration already established with the Japanese team of investigators makes this project feasible. This investigation will obtain, interpret and disseminate the first shake table results for full-scale bridge columns. Comparison of results for the U.S. and Japanese specimens with past tests and with analytical simulations will provide a critically needed assessment of the adequacy of reduced-scale models and tests conducted at altered strain rates. Comparison of U.S. and Japanese design practices in light of observed performance will provide new insights into bridge behavior. It will provide missing data needed to increase confidence in analysis methods and validate (or improve) current design methods. This research is of high priority nationally to federal and state bridge agencies and industry.The impact of the project will be broadened by the planned dissemination of results and by the substantial anticipated exchange of faculty members, students, professionals, and others.