Toshikazu Yamada

Control performance of active-passive composite tuned mass damper

This paper reviews an active control algorithm adopted for an active-passive composite tuned mass damper, which is a unique vibration control device equipped into an office building in Tokyo in 1993. The main purpose of this device is to subdue the response motion of tall buildings under random disturbances such as wind pressures and small earthquakes. The main topics in this paper are: (1) the principle of the acceleration feedback algorithm, (2) the expected control performance, (3) the multi-modal control algorithm, (4) the observed performance of the applications using the algorithm.

Apparatus for accelerating response time of active mass damper earthquake attenuator

A positive vibration suppression apparatus is disclosed, which suppresses vibrations of a building caused by earthquakes or winds by applying a control force to the building. The apparatus comprises a weight provided on the top of the building in a suspended form to reduce friction and an actuator provided between the weight and the building. The vibration suppression apparatus is controlled through sensing of the vibrations of the building and weight by a sensor, whereas for excessive vibrations of the building the vibrations of the weight are made close to the vibrations of the building to protect the apparatus, because the capacity of the vibration suppression apparatus is limited. Further, in an oil hydraulic system for obtaining a great control force, small and large size oil hydraulic pumps connected to respective small and large size electric motors and an accumulator are provided in parallel, so that the apparatus is warmed up at all time for oil hydraulic control with low power consumption. Two or more vibration suppression apparatuses are controlled at the same time according to the shape of the building to cope with torsional and secondary vibration components.

Seismic design of a tall building with energy dissipation damper for the attenuation of torsional vibration

This paper reports a structural design method of a 100 m tall building using passive energy dissipation dampers, which made the unique architectural form of the building structurally feasible. This tall building will have 21 floors above ground and three basement floors, and will be an educational facility in the city of Osaka. The shape of the building is a unique combination of a rectangular parallelepiped and a quadrangular pyramid with a spacious atrium and a spherical hall inside. The main structure is composed of rigid steel frames, and the outer ones are equipped with dampers. The passive energy dissipation dampers applied to this project are mild steel plates with honeycomb‒shaped openings and capable of large elasto‒plastic deformation. They are expected to perform good energy absorption during earthquakes. As they are installed between vertical spans inside columns, they are consistent with the architectural planning. A structural problem caused by torsional vibrations in the event of an earthquake would be serious if the complex form of the building had not been considered. One of the major objectives of implementing such dampers is the stiffness and strength enhancement that adjusts and reduces the torsional vibrations to the normal level commonly encountered in a standard tall building design process. Time‒history analysis is carried out using a dynamic model to examine the structural performance of the building, which proves that the building is kept intact even under a large earthquake whose peak velocity is 50 cm s−1.

High Performance Passive Damper With Ingenious Hydraulic Valve System

Newly developed ingenious hydraulic valve system (MAIKO-Ben) autonomously controls the flow valve opening between two hydraulic chambers utilizing the pressure balance between them without an external power source. This impressive function can create a passive hydraulic damper with high performance equivalent to that of previously developed semi-active damper that can absorb much more structural vibration energy than a conventional passive damper. This damper works a semi-active damper while remaining passive. First, we explain the self-regulating hydraulic mechanism of this valve system. The flow control valve is activated through the hydraulic power accumulated in rather small buffer placed between the two hydraulic chambers, and produces maximum or minimum damping coefficient based on the pressure balance between them. Second, we present the results of dynamic loading tests conducted on a full-scale prototype damper (maximum force: 2MN) under both sinusoidal waves and non-stationary seismic response waves. It is confirmed that the developed device showed excellent energy dissipation capacity as expected, and also that the damper’s dynamic characteristics could be well simulated through simply modeling the above hydraulic mechanism. According to these results, it is verified that the MAIKO-Ben system has enough promise to be applied to the real buildings.Copyright