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For the past several years, large scale earthquakes happened. A lot of industrial facilities were damaged. For example, a lot of power plants were stopped in The 2011 off the Pacific coast of Tohoku Earthquake or The Southern Hyogo prefecture earthquake in 1995. These earthquakes had larger acceleration level than the seismic design level. Therefore, the earthquake proof measures are required. In this study, earthquake proof effect of the beam with initial torsion is focused. The design guidelines for application to the thin-walled beam with initial torsion structure is proposed. The thin-walled beam with initial torsion is modelled by FEM and calculated. The static and dynamic loading characteristics of the actual beams are compared with the analytical results to verify the validity of the analysis. The comparison result of analysis and experiment shows that the FEM analysis of the beam element is valid up to 0.23 aspect ratio. The analysis was used to clarify the static characteristics, for example, stiffness or displacement, and dynamic characteristics, for instance, frequency or vibration mode, under the conditions of the aspect ratio and total torsion angle of the beam. By the time history analysis, it was shown that the vibration response changed by the initial torsion, and that it was possible to reduce the acceleration response. In order to evaluate the response reduction effect, the acceleration response for the condition of the aspect ratio and total torsion angle of the beam was analyzed. And the response reduction map is proposed. Using this map, it is possible to estimate the advantage of the initial torsion effect for the response reduction effect in a simple manner.

In the structures whose bottoms is not fixed such as home appliances and furniture, the falls and the slip movements are caused by vibrations such as earthquakes. There is an urgent need to develop fall prevention measures in order to reduce the damage caused by falls and slip movements of structures. The purpose of this study is to clarify the effect of changes in the coefficient of friction on the falling and slipping of structures by analyzing the coefficients of static and dynamic friction separately about dynamic behavior when slipping occurs during rocking vibration. As a result of analyzing the rocking vibration that changed the shape of the structure, it was clarified that the structure wasn’t fall and the slip displacement was the smallest under the conditions when rocking vibration occurred and the height of the structure was low regardless of any degree of freedom. It was clarified that the slip displacement was smaller in 2-DOF system by comparing 1-DOF system and 2-DOF system. It is thought that one of the reasons for this is the fact that the rocking angle reduces and collision frequency increases. 2-DOF system has many collisions because it collides not only between grounds and the structure but also between the upper and lower structures. Therefore, it is considered that the energy consumption of 2-DOF system is larger and the slip displacement is smaller than that of 1-DOF system.

This paper deals with seismic isolation system with nonlinear characteristics for vertical ground motion. The vertical seismic isolation system consists of a rhombus shaped link mechanism, a tension coil spring, and a leaf spring. The restoring force of the system is obtained by the sum of the restoring force of the buckling deformation of leaf spring and the restoring force of the rhombus shaped link. The purpose of this paper is to create design guidelines for seismic isolation system. Random waves were input to the experimental model with nonlinear restoring force, and the reduction effect was about 0.1 times. In addition, the validity of the analytical model was confirmed by comparing the experimental results with the calculated results. By setting dimensionless parameters and performing analysis, combinations of parameters with high seismic isolation effect were clarified. When the seismic isolation object was determined, a guideline on how to design it was given to make the seismic isolation design easier.

A flexible string is used at various places. Typical examples are a cable for power transmission and communication and a wire for cranes and elevators. In addition, there are the uses such as a fly-fishing line, climbing rope and a mowing machine to cut turf by turning a nylon string. In the past study, a string pendulum was paid attention as the basic motion of the string. An analysis model of the string pendulum was made and appropriateness of the modeling and the behavior of the string pendulum were clarified. However, axial elongation is not considered. In fact, the axial elongation affects their behavior such as axial micro vibration or restoring force of the elongation. Therefore, it is necessary to consider the axial elongation to grasp the behavior of the string more exactly. In this study, an accelerated motion of the string such as the casting motion is focused on and analyzed in consideration the axial elongation then appropriateness of the modeling is verified by comparing experimental results and analysis results. Furthermore, relations of the axial elongation and an accelerated motion are investigated. In this paper, the behavior is investigated focusing on the velocity of the tip of the string. As a result, strain energy is stored and then converted into kinetic energy, thereby increasing the velocity.

A flexible string is used at various places. Typical examples are a cable for power transmission and communication and a wire for cranes and elevators. In addition, there are the uses such as a fly-fishing line, climbing rope and a mowing machine to cut turf by turning a nylon string. In the past study, a string pendulum was paid attention as the basic motion of the string. An analysis model of the string pendulum was made and appropriateness of the modeling and the behavior of the string pendulum were clarified. However, axial elongation is not considered. In fact, the string extends in the axial direction by the mass of itself and the external force, and it is expected that the behavior of the string is affected by the axial elongation. Therefore, it is thought that it is necessary to carry out numerical simulation in consideration of the axial elongation in order to grasp the behavior of the string more exactly. In addition, it is indispensable to take elongation into account when we analyze the behavior of a string-formed structure producing the great amount of elongation such as the rubber string. In this study, an analysis model considering axial elongation is made. The behavior of the string pendulum and the behavior when the string is given initial elongation and is released are paid attention and appropriateness of the modeling is verified by comparing experiment results and analysis results.

The rocking vibration with friction is focused in this study. The fall down conditions of the rocking system with friction are clarified. Rocking vibration is the rotational motion around the both ends of the structure and occurs when the structure is excited. In this report, the behavior of single-degree-of-freedom rocking system and two-degree-of-freedom rocking system with friction are taken into consideration. An analysis model is proposed and the response is calculated in the case that the structure is excited by sinusoidal wave and seismic wave. In order to estimate the parameters to prevent the fall down in a simple manner, two state judgement maps are proposed. One is the “Input variation map” focusing on the parameters of input sinusoidal wave and the other is the “Form variation map” focusing on the parameters of the structure form. From the analysis results, it was possible to clarify the basic characteristics of the rocking vibration with friction from the aspect of the input waves and the dimensions of the structure.

The purposes of this study are to propose the seismic isolator which has the new characteristic using the thrust bearing, and to propose a simple method for the seismic isolation design. It is thought that the seismic isolator using the thrust bearing depends on the seismic input motion because it is nonlinear system with the geometric nonlinearity. Therefore, it is found that the response magnification changes with respect to the maximum acceleration of the seismic wave and the rotation spring constant, and the domain which has the response reduction effect on a response reduction map was acquired. It is thought that the proposed seismic isolator has the following characteristics from the analytical result. The initial state of the isolator is important in order to acquire the response reduction effect to the various excitation directions. The response reduction effect is small in the case of a long-period earthquake ground motion, and the seismic isolator carries out seismic isolation effect by making a rotation spring constant small. The response reduction effect is large in the case of a short period earthquake ground motion, and the rotation spring constant of the seismic isolator should be enlarged not to the response becomes unstable. Moreover, it is possible to make the seismic isolation design simply by applying the response reduction map.

Lure fishing and fly-fishing have been positioned as sports deliberately different from the traditional Japanese fishing-style. In the case of fly-fishing, casting is the element which anglers must master in order to cast a fly, done so by using the weight of a line. This study uses experimental and computational analysis to investigate the dynamic behavior of a fly line. Fly-fishing is constituted by various elements, but the importance that casting holds is extremely large. Fling speed, the casting process and the loop shape of the line while in flight are important that casting holds is extremely large. Fling speed, the casting process and the loop shape of the line while in flight are important for the proper presentation of flies. Moreover, the shape of a fly line is also important for a long cast or controlled cast. Fly is a lure that imitates an aquatic insect or a small fish, and becomes the prey of the target fish. And, there are countless of fly patterns. Therefore, anglers necessary to select an appropriate rod or line according to the size of the fly. In this paper, a rod, a line and arms are modeled by using rigid bodies and links. The time history behavior of the model is calculated by pseudo angler velocity of the arms. The validity of the model in detail is investigated. And, proper rod and line in accordance with the fly of the size is verified.

This paper deals with the response reduction effect by friction under 2-dof system. The friction behaviour is effective for dissipating seismic energy. Therefore, in recent years, the installation of an isolator and a damper with frictional element in industrial facilities has been investigated. In addition, the seismic response is reduced by the frictional vibration occurring between piping and support system. However, the seismic response of a 2-dof friction system depends on system parameters such as natural frequencies and the mass ratio of the structure by support. A great deal of time is required for non-linear analysis to obtain optimum system parameters. The present study deals with the “Response Reduction Map” for a 2-dof friction system. This map shows the area that the response magnification is less than 1 and less than the response of a linear system. Firstly, the response reduction map by actual seismic wave is shown. Secondly, the response reduction map by the artificial seismic wave calculated from the design spectrum is shown. Optimum friction forces for reducing the seismic response of 2-dof friction system can be easily obtained by this map without non-linear time history analysis.

For the past several years, large scale earthquakes happened. A lot of industrial facilities were damaged. For example, a lot of power plants were stopped in The 2011 off the Pacific coast of Tohoku Earthquake or The Southern Hyogo prefecture earthquake in 1995. These earthquakes have larger acceleration level than the seismic design level. Therefore, the earthquake proof measures are required. In this study, earthquake proof effect of the beam and the long column having initial twist is focused. The design guidelines for application to the pre-twisted beam structure and the long column structure is proposed. The pre-twisted beam and long column are modelled by FEM and calculated. The natural frequency of the pre-twisted beam and long column are related to the Young's modulus, density, length and cross-sectional area. The tendency of the natural frequency respected to the total twisted angle and the aspect ratio of the cross-section is obtained considering the vibration mode and the natural frequency. Furthermore, when attention is focused on the vibration mode, the influence of the total twisted angle is different for the modal shapes, and the case where the modal shapes are interchanged is shown. The acceleration response to the vibration input is determined by the natural frequency of the primary cross-section, the aspect ratio and boundary conditions. In order to evaluate the response reduction effect, the acceleration amplification respected to the total twisted angle and the 1st natural frequency of the system is analyzed. And the response reduction map is proposed. Using this map, it is possible to estimate the advantage of the pre-twisted effect for the vibration characteristics in a simple manner.