Yasuo Kajikawa

Application of the distinct element method to the analysis of the concrete members under impact

Abstract In this paper, the distinct element method is applied to the analysis of the behavior of a structure under impact. At first, this method is applied to the one-dimensional wave propagation problem by comparing with the experimental results and the theoretical results. The effectiveness of this method is confirmed by including not only elastic behavior but also the fracture of a structural member. Second, this method is developed to two-dimensional problems to simulate the behavior of a simply supported beam under an impact load. Finally, it could be shown that this method is effective to simulate wide phenomena from elastic behavior to a fracture under impact.

Numerical study on the vibrational serviceability of flexible single span bridges with different structural systems under traffic load

Bridge vibration is the major focus of environmental issues, especially in urban areas where the ground is soft. The structural system of the bridge greatly influences the ergonomic serviceability of the bridge, infrasound and ground vibration by vehicular live load. This paper discusses the vibrational serviceability of bridges, considering the interaction between vehicular live load and the structural systems of the bridge. The numerical approach with Finite Element Analysis was conducted to understand and evaluate the fundamental dynamic behaviour of flexible single span bridges under vehicular live load for four types of different structural systems, including the adjacent approach parts of the bridges.

Ground Vibration Measures for the Rocking Vibration of the Piers with Two-Box Girders Bridge

Vibration caused by running vehicles on a highway bridge is spread to the superstructure, substructure s and ground. The ground vibrates both in horizontal and vertical direction. When vehicles load at the tip of the cross beam in the T -shape d pier , rocking vibration of the pier occurs. Its ground vibration in transverse direction is the biggest. In the two -box gi rders bridge, which bearings are installed at the tip of the cross beam of the T -shape d pier , the ground vibration has greatly occurred due to the rocking vibration of the pier. Two measures to mitigate the vibration are propose d in t his study. The evaluat ion the change of the vibration characteristics and effects of the measures to mitigate the vibration are also discussed in the study .

THE STRENGTHENED EFFECT OF ENDURANCE IN EXISTING STEEL BRIDGE

耐力不足となっている既設鋼橋の補強工法として, カバープレート工法と外ケーブル工法がある. その耐力的な補強効果は確認されているが, 耐久的な補強効果については明確になっていない. 特に, 疲労損傷の原因となることの多い二次応力の動的荷重下での挙動については, ほとんど研究されていない. そこで本研究では, 車両の大型化対策として外ケーブル補強された単純活荷重合成Iげた橋を対象に, 数値解析によって算出する動的荷重下での橋梁部材に作用する一次応力および二次応力の妥当性の検証を行い, その数値解析を用いて, カバープレート工法と外ケーブル工法の疲労から決まる耐久性に対する補強効果について検討するものである.

STUDY ON STRUCTURAL CHARACTERISTICS OF PRESTRESSED CONCRETE DECK BRIDGE SUPPORTED FROM BELOW BY CABLES

張弦桁橋は, ケーブルで主桁を下方から支持した自碇構造の橋である. 本論文では, 多数のストラットを有する張弦桁橋の基本的な力学特性を明らかにするとともに, 主桁剛性が全体系の静的特性, 動的特性などに及ぼす影響について検討した. また, 構造解析の妥当性を確認するために行った実橋における静的・動的載荷試験結果を示した. さらに, 主桁剛性が, 車両走行時および破壊時の挙動に及ぼす影響について検討を加えた.

Factors affecting the perception of low-level vibration

SummaryThe level at which vibration becomes a nuisance is low, well below the vibration intensity discussed with regard to the health of industrial workers in the International Standard ISO-2631 draft. The relationships between the various factors and the human response to low-level vibration generated by vehicular traffic, are discussed from the results obtained from questionnaires.A female may respond to a lower level than a male. There is no difference in response to low-level vibration between standing and sitting postures. Accompanying noise distracts the perception of low-level vibration, however at high levels, the effect of distraction is reduced.