Toshio Chiba

Positive use of damping devices for piping systems — Some experiences and new proposals

Abstract An increase of the damping ratio is known to be very effective for the seismic design of a piping system. It is reported that the energy dissipation in piping supports contributes to increase the damping ratio of the piping system. In this paper, with regard to increasing the damping and reducing the seismic response of the piping system, three application methods of damping devices used in other engineering fields are reviewed: (1) direct damper, (2) dynamic vibration absorber, and (3) connecting damper. Based on the results of this review, the following three types of damping devices for piping systems are introduced: (1) visco-elastic dampler (direct damper), (2) elasto-plastic damper (direct damper), and (3) compact dynamic absorber (dynamic vibration absorber). The dynamic characteristics of these damping devices are investigated by a component test and the applicability of them to the piping system was confirmed by the vibration test using a three-dimensional piping model. These damping devices are more effective than mechanical snubbers to suppress the vibration of the piping system.

Shaking Table Test of Passive Controlled Structure With New Friction Damper

Under the effect of a large earthquake, the range of plastic comes into the column and the beam of the frame structure. By using energy dissipation devices, it is possible to reduce the response and the damage of the structure. A friction type damper which was a compact form and had high damping characteristics, was developed. It was made of steel plate, aluminum sliding plate, rubber washer and high tension bolt. To validate the performance of the new damper, the elemental tests and the shaking table test were conducted. In the shaking table test, frame structure composed of full scale member with friction damper was excited by actual seismic wave. As a result, it was found effective and had a high damping performance. This paper mainly reports the results of the shaking table test.© 2007 ASME

Seismic Isolation of Base-Isolated Vending Machine With Air Dampers

By setting the isolation system between the foundation of the house and the foundation ground, it makes it possible to scale back the influence of the earthquake. A sliding isolator, which is compact and has high isolation characteristics, had been developed. This isolation system of the house have found effective and had high performance. This system was applied to the vending machine. Although the sliding isolator has been shown to be effective, it required the wide space around the vending machine. By using the base isolation combined with the air damper, it allowed to use in the narrow space area. It is useful when the vending machine is set in front of the wall. A sliding isolator combined with air damper has high isolation characteristics.Copyright

Development of Base-Isolation House Using Sliding Device

By setting the isolation system between the foundation of the house and the foundation ground, it makes it possible to scale back the influence of the earthquake. A sliding isolator, which is compact and has stable isolation characteristics, had been developed. It was made of a plate with multi convex cell and a sliding plate. This system is a sliding isolator with multipoint contact. The static tests, the shaking table tests and analysis were conducted to confirm the damping capacity of the sliding device. In the element tests, the coefficient of static and dynamic friction and the change in the friction of the total system resulting from construction error were investigated. Movement of the base-isolated house and twisting of the base-isolated house with eccentric load under the actual earthquake loading were surveyed in the shaking table tests. As a result, it was effective and had a stable performance.Copyright

Dynamic Behavior of the Five Storied Pagoda Under the Earthquake and the Wind

Five storied pagoda is built of wood and is known as a high earthquake proof structure. The pagoda is composed of the frame and the center column. The center column is structurally independent of the frame structure. Many researchers have mainly been interested in its dynamic characteristics under the earthquake. They have focused on the acceleration response of the pagoda. This time, we observed not only its dynamic characteristics under seismic load but also under strong wind load. We focused on the displacement response of the pagoda. By integrating the acceleration data twice, the displacement of the structure was obtained. Under low level earthquake, the pagoda swayed about the central axis of the structure. On the other hand, the pagoda was statically deformed by the wind pressure and swayed in the deformed central axis of the structure. The dynamic behavior of the pagoda in the wind is distinctly different from that of the earthquake.Copyright

Development of Passive Controlled Structure Assembled With L-Type Diaphragm

Using the high-strength bolted connection, it is possible to control the quality of the joint and improve the construction of the structure. By setting the energy absorption mechanism on the structure and enhancing the damping effect, it makes it possible to scale back the influence of the earthquake. Based on the statement above, a new type of beam column joint (L-type Diaphragm) was developed and tests and analysis were conducted to validate the performance of this joint and the energy absorption characteristics at the end of the beam were surveyed. The stress transfer mechanism of the joint was investigated in the shaking table test of the actual size frame structure with this joint. As a result, it was found effective and a higher reliability.Copyright

A Dynamic Behavior of the Frame Structure Allows the Columns to Uplift

To investigate the dynamic behavior of the frame structure which allows the columns to uplift, a shaking table test was conducted by using a 4-story frame structure model. The effect of the absence or presence of the uplift and the damper in the column on the dynamic behavior of the structure were clarified. Dynamic response of the traditional frame structure with damper was compared to that of structure with damper in the columns. By using damper in the columns, the seismic impact of the structure was controlled. It is confirmed that the frame structure which is allowed the columns to uplift has an adequate seismic ability.Copyright

Baseline Correction Method and Strong Motion in 2003 Off Tokachi

Observation system of the seismic wave has greatly progressed and many accelerometers have been set all over Japan. Furthermore, the data processing procedure was developed and the reasonable permanent displacement and the displacement wave were going to be obtained from the measured acceleration data. The baseline correction method was adopted as a data processing procedure. To estimate the adaptability of the baseline correction method, the permanent displacements and displacement wave of major records in 2003 Off Tokachi Earthquake were calculated. The displacements were compared with the data of JAPAN Geographical Survey Institute and Port and Harbor Research Institute. These data were fairly similar to each other. Additionally, sloshing response of the fired large liquid storage tank in Tomakomai was calculated using these data. The baseline correction method presented here can be used successfully to correct strong motion records and present the displacement data for the seismic design and the vibration test.Copyright

Work of Shaking Table

To improve the reliability of the structure under the severe earthquake, many shaking table tests have been conducted. In the shaking table tests, the test model on the shaking table was excited by the acceleration wave. In the shaking table test, it is important to account for the input energy and work by the shaking table on the test model. From an energy point of the view, the input energy of the shaking table test is discussed.Copyright