Study on the methods for the structural control of bridges against extreme seismic actions beyond the design assumptions

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14816
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22020:Structure engineering and earthquake engineering-related
• Research Institution: Gunma National College of Technology
• Principal Investigator: INOUE Kazuma 群馬工業高等専門学校, 環境都市工学科, 准教授 (50825982)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 2方向地震動 / 地震応答解析 / 数値解析 / 免制震橋梁 / 構造制御

Outline of Final Research Achievements

Numerical analyses of the nonlinear seismic response of bridge models and soil have been conducted, focusing on the bi-directional horizontal seismic motion and multiple seismic actions as extreme seismic actions not assumed in the seismic design.
In particular, in the analysis of seismic isolation and vibration control bridges, the maximum response displacement tended to be the largest for both bearings with coupled nonlinear response in the horizontal plane and bearings with circular trajectory input in the bi-direction. In other words, the bi-directional input with circular trajectory may provide a safer design for seismic design of seismically isolated bridges. In addition, a unidirectional seismic control damper, such as a cylinder damper, can be placed in two orthogonal directions, making the structure less susceptible to the effects of the bi-directional horizontal input.

Free Research Field

地震工学

Academic Significance and Societal Importance of the Research Achievements

水平２方向入力地震動が橋梁や地盤の非線形応答に及ぼす影響を示すとともに，現在，免震橋梁の耐震設計は水平１方向入力地震動に基づいて行われていることから，水平２方向入力の影響を考慮した耐震設計が行われるべきと考えられる．
研究成果の概要で述べたように，水平２方向入力に対する耐震安全性確保の方策として，方向別独立モデル（制震ダンパーを方向別に配置したモデル）を採用することは，現在の耐震設計で考慮しない水平２方向入力地震動の影響や不確定性の多い地震動に対する方策の一つであることが示された．