報告書番号

N10045

タイトル（和文）

繰返し載荷履歴を受けたRC部材の固有振動数低下の検出－ハンマリングによる自由振動試験の適用性検討－

タイトル（英文）

Detection of natural frequency reduction in RC members subjected to cyclic loading -Application of a free vibration test based on a hammer impact-

概要 （図表や脚注は「報告書全文」に掲載しております）

本報告は，せん断補強筋のないRC部材を対象として，静的な繰返し載荷実験で与えた損傷による固有振動数の低下現象を自由振動試験に基づいて検出した結果を示すものである。具体的には，載荷実験の除荷時に設けたインターバルにおいてハンマリングによって部材の自由振動を励起させ，その卓越振動数から推定した固有振動数と載荷実験における経験変形角との関係を明らかにした。本検討から，最終的にせん断破壊するRC部材においても，これまで曲げ破壊先行型部材を対象として研究されてきた，固有振動数の低下量に基づく健全性診断を適用できる可能性を示した。

概要 （英文）

This report presents detection of natural frequency reduction in RC members due to propagation of shear cracks developed by a series of cyclic loading experiments. The RC members were designed and constructed without stirrups such that they exhibit shear failure. The cyclic static loads were applied to the RC members by using a horizontal actuator, while two vertical actuators restrain the rotation of the top slab of the RC members. The natural frequency of the damaged members was obtained by a hammer impact test, which was conducted during the unloading intervals of the static loading experiment. The reduction of natural frequency due to the propagation of the shear clacks was successfully detected from the hammer impact tests. And also, the relationships between the experienced maximum drift angle and the reduction of the natural frequency were obtained to show the applicability of the vibration based the damage diagnosis for RC structures which exhibit shear cracks.

報告者

キーワード