A Atudy of Mutual Reactions among the Super-structure and Sub-structure of the Steel Bridge and Its Foundation

1987 Fiscal Year Final Research Report Summary

• Project/Area Number: 61550324
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 土木構造
• Research Institution: Technological University of Nagaoka
• Principal Investigator: TORII Kunio Professor of Technological University of Nagaoka, 工学部・建設系, 教授 (00126476)
• Co-Investigator(Kenkyū-buntansha): IKEDA Kiyohiro Assistant professor of Technological University of Nagaoka, 工学部・建設系, 助教授 (50168126) ; KONAGAI Kazuo Assistant Professor of Institute of Industrial Science, Tokyo, 生産技術研究所・第1部, 助教授 (50126471)
• Project Period (FY): 1986 – 1987
• Keywords: Steel Bridge / Earthquake Resistance / Dynamical Mutual Reaction / 動的相互作用 / 弾性波動

Research Abstract

The movable shoes and expansion joints of the bridge give negative effects to its fabrication cost, earthquake resistance and comfortable driving. The main theme of this project is to show that these parts can be removed from the steel bridge. In order of prove this, analysis of the complete model which involves not only super and substructure but also its foundations. Modeling of the stiffeness of the foundation which is most difficult, was able to be exhibited in this project.
The waves which are radiated from the pile and the surface of the foundation, were divided into several factors and the equivalent model to each factor was built. They were conbined suitably to express the mutual reactions among the portions constructing the bridge system. These models, expressing with the spring, mass and the dash-pot, enable the non-linear phnomena of the to be anlysed. As the result of calculations and experiments, the following items were able to be shown.
1. The foundation of the footing can be replaced to the equivalent forked model. The spring constant is proportional to the cicruit length of the footing and the attenuation constant of the dash-pot is proprtional to the bottom area of the footing.
2. The pile foundation can be replaced to 2 or 3 series forked models because the wave diffusing cylindrically, exells.
3. As to the movable shoes, reliablity of injury is very high on occasion of a severe earthquake.
4. The structure from which movable or hinge shoes and expansion joints are removed, is not so expensive and rather economical on some conditions. The reliablity of injury of this type is less than otherwise.