Hayato Asada

RECONNAISSANCE OF DAMAGED STEEL SCHOOL BUILDINGS DUE TO THE 2011 TOHOKU EARTHQUAKE

An outline of a reconnaissance of steel school buildings damaged by the 2011 Tohoku earthquake is presented. In this reconnaissance, a total of 216 facilities have been investigated by the Steel Structure Working Group of the Subcommittee on Seismic Performance of School Buildings, Architectural Institute of Japan. The damage to structural elements, connections, non-structural elements, foundation and surrounding soil, as well as the details including building history and seismic retrofit have been recorded and the overall damage has been evaluated based on the “Standard for Post-earthquake Damage Evaluation of Damaged Buildings” published by the Japan Building Disaster Prevention Association. Not only seismic damage but damage caused by the devastating tsunami are also covered. Detailed analysis of the damage to individual structural and non-structural components are presented in following papers.

PULL-OUT TEST OF ANCHOR BOLT FOR FASTENING LEAD DAMPER TO CONCRETE FOUNDATION

Pull-out tests on anchor bolts for fastening lead damper to concrete foundation were conducted to evaluate factors affecting pull-out behavior of anchor bolts. The main parameters were type of anchor bolt commonly used for anchorage of lead damper and layout of reinforcements around anchor bolt. The following results were obtained : (1) Vertical reinforcements arranged around anchor bolt contribute to increase in concrete breakout strength. (2) For long nut type anchor bolt, long nut length covered anchor bolt must be treated with enough care to avoid slipping anchor bolt. Because slipping failure lead to decrease in tensile strength and increase in pull-out displacement at failure. (3) The slope of the concrete cone was much flatter than 45 degree assuming in design procedure, regardless of the embedment depth, anchor type and reinforcement pattern. (4) Based on test results, simple concrete failure model was proposed. Using this model, effective radius of projected area were assessed 0.81le - 0.96le. These values were close to effective radius 1.0 le in existing design formula according to AIJ.