The objective of this Rapid Research Response (RAPID) award is to investigate the performance of buildings with structural walls in the Tohoku, Japan, earthquake of 2011. The goals of this investigation are (1) to collect quantitative data on the seismic performance of buildings with dominant structural walls in the Tohoku region, (2) to compare it with similar information obtained in Chile, (3) to identify the causes of successes and failures observed in the two locations, (4) to test the ability of state-of-the-art simulation tools to reproduce what occurred in the field, and (5) to summarize the findings in brief statements and/or algorithms that can be used to design safer structures. Building standards in Chile, Japan, and the US are comparable. Nevertheless, the Maule, Chile, Earthquake of 2010 caused severe structural failures that demonstrated that there are critical missing links in our technology related to earthquake resistance of mid- to high-rise buildings with structural reinforced concrete walls. In Concepción, Chile, where the peak ground acceleration did not exceed 0.4g, nearly 7 percent of the buildings with more than 10 stories were evacuated and scheduled for demolition. In contrast, the intensity of the ground motion caused by the earthquake of 2011 in the Japanese region of Tohoku was as large or larger than in Concepción (with peak ground accelerations exceeding 2g), but the frequency of building damage was lower.
The knowledge to be generated by this investigation will contribute to the safety of urban populations in seismic regions. The investigation will lead to elimination of massive economic and human losses in future earthquakes. In addition, the necessary fieldwork will involve the participation of students in a rich educational and cultural activity. The findings of the investigation will be made available to the public through NEEShub.org, an easily and universally accessible NSF-funded web site dedicated to improving engineering knowhow.
The main goal of this project was to preserve valuable perishable information on the seismic response of RC buildings with structural walls. Five reinforced concrete buildings damaged by the March 11th, 2011 Tohoku Earthquake were surveyed. One of these buildings was instrumented and the others were within 500 m from the instrumented building. These buildings had been evaluated and retrofitted before the earthquake of 2011. Despite the strengthening done before 2011, the surveyed buildings were damaged by the Tohoku Earthquake and had to be either demolished or repaired. Reasons to demolish went beyond safety concerns and included economical factors and the age of the structures. Nevertheless, there were several instances of severe damage to retrofitted structural elements that merit careful study. Damage was documented in detail using systematic nomenclature. Original construction and retrofit documents were obtained and digitized. These documents, the observations documented, and acceleration records were made available to the public at nees.org/warehouse/project/1122. Nees.org houses the largest collection of quantitative data on earthquake engineering available. Most of the data at nees.org come from the laboratory. This project added data from the field, creating an unprecedented opportunity to compare what we have learned in the lab with direct evidence from the field. The data collected constitute a rich resource to test 1) our understanding of the response of reinforced concrete structures to strong ground motion and 2) the effectiveness of state-of-the-art strengthening techniques.
