This thesis includes experimental and theoretical work performed to investigate the behaviour of ground anchors in sand. The anchor footing used was a circular plate connected to a tie rod. The experimental work was carried out by installing the anchor in a l830mm x 1830mm x l220mm deep tank containing dry sand. The sand sample was prepared by using a vibrator fixed to the bottom of the tank. The anchor was pulled out at a constant rate of strain and the load-displacement curve was recorded on a plotter. The vibration of the tank was defined by deter.mining the acceleratton and amplitude of the motion in the horizontal and vertical directions. A density tube and a hydraulic gauge were designed to investigate the distribution of stresses in sand. The variation of the vibration time, the constant rate of strain, the shaf V plate diameter, the plate thickness/plate diameter, and the boundary distance with the load-displacement curve were also investigated. The load-displacement curve of different diameter plates embedded at various depths for different times of vibration were recorded. To investigate the behaviour of ground anchors theoretically, the finite element technique was used and a computer progra~ developed. A linear stress-strain relationship was used to predj.ct and investigate the behaviour of the anchor. A non-linear stress-strain relationship and a failure criterion were also used to predict the load-displacement curve of the vertical anchor. The effect of the parameters which were investigated experimentally were also examined. The distribution of the load on the anchor plate and the extent of the failure zone were plotted. The predicted and experimental results in this thesis were compared with laboratory and field results obtained by previous researchers.

本論文ではロードノイズに関するタイヤ振動特性を予測する上で必要となるタイヤモデルの構築と接地・転動時のタイヤ振動特性の変化要因について解明することを目的にしている.薄肉円筒シェル理論に基づきタイヤばね付きリングモデルを構築し,Rayleigh法を用いてタイヤの固有振動数の式を導出した.また,径方向モードに着目し,非接地・転動時,接地・非転動時,接地・転動時におけるタイヤ振動特性の理論解析を行い,その特性を明らかにした. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.