Haruhiko Kurino

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