In December 2010, two full-scale four-story reinforced concrete building structures were tested at the National Research Institute for Earth Science and Disaster (NIED) E-Defense shake table facility in Miki City, Japan under increasing multi-directional seismic excitations to near collapse. The principal investigator and several U.S. researchers under NSF award 1110860 collaborated with Japanese investigators to instrument the specimens and observe the performance. Beams, columns, and slabs in the structure performed as expected. However shear walls and beam-column joints showed severe damage and loss of integrity even though designed according to current earthquake engineering practice. The experimental program presents wealth of data to study the accuracy of current analytical tools. Current analytical tools are calibrated based on pseudo-static experimental investigations of individual structural components. The structural engineering field has therefore resorted to a number of extrapolations to form analytical models of complete structural systems. The obvious consequence of such extrapolations is an inability to verify the validity of system level analytical results. The recorded data of test series presents a unique opportunity to study the accuracy of currently used analytical tools, identify parametric assumptions, and improve on analytical method for structural systems. Through this project critical guidance will be delivered on formulating analytical models for this type of structures.
The shake table at the Japanese NIED/E-Defense facility has no counterpart in the world in terms of capacities of testing full-scale buildings for earthquake motions. The test series were performed on a full-scale four-story reinforced concrete building structure that reflected closely current U.S. practices for earthquake design. This test series is the only one to date of a full-scale, modern, seismically designed reinforced concrete structure subjected under controlled conditions to a real seismic event. The performance of structures was worse than anticipated, which raises serious questions about the adequacy of current seismic design and construction practices. This project will uncover the causes of this performance and provide recommendations for improvements in design practices. The research objectives will be achieved in close collaboration with Japanese researchers. A report and publications will be submitted to U.S. and Japanese journals to present key results to a broad audience. The Principal Investigator will use this project to strengthen ties with Japanese researchers and the E-Defense center. Graduate engineering students the University of Texas will benefit through classroom instructions and involvement in the research including travel to Japan to learn from Japanese researchers at the forefront of the field of earthquake engineering.
