Strength, stiffness, and damage of reinforced concrete buildings subjected to seismic motions

Kwon, Jinhan
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Current analytical tools were calibrated mainly using pseudo-static experimental investigations of individual structural components. Relatively few tests have been performed on reinforced concrete structural systems under realistic boundary conditions and even fewer exist that were conducted dynamically due to the high costs and experimental challenges. Thus, the structural engineering field has resorted to a number of extrapolations from limited test data to form analytical models of structural systems they design. It is therefore no surprise that blind prediction contest results for structural strength and deformation are typically several times higher and lower than those from experiments. A complete system of a full-scale, four-story, reinforced concrete structure was tested under increasing seismic excitations, to near collapse damage states, one the National Research Institute for Earth Science and Disaster Prevention (NIED)/E-Defense shaking table in Japan. A moment frame system was adopted in one direction and a pair of shear walls incorporated in the exterior frames in the other direction. Wherever possible, minor adjustments to the designs were made to bring the final structures closer to U.S. seismic design provisions. No other tests currently exist that provide behavioral data about a complete, seismically detailed, reinforced concrete structural system tested under such realistic boundary conditions. Comprehensive and in-depth analyses were performed in light of the NIED/E-Defense test data to 1) assess the validity of current behavioral knowledge and design codes; 2) to assess the accuracy of current analytical methods for this common type of structure; 3) to recommend improvements and ways forward on both fronts. Implications of test results to U.S. seismic provisions and recommendations for estimating structural strength and stiffness of reinforced concrete buildings were made based on comparison between the estimates from the current analytical methods and the actual seismic behavior of the NIED/E-Defense test data.