Hiroki Hamaguchi

Active microvibration control of precision manufacturing factories with smart structure using piezoelectric actuators

In order to achieve more perfect vibration-free environment in precision manufacturing facilities such as semiconductor manufacturing factories, and apply steel frame structures to semiconductor manufacturing factories of the next generation, a smart structure was tested for active microvibration control of a 2-story steel frame building model of a 5 X 3 X 4H m outer size and a 2,500 kg total weight which was excited by ambient ground vibration. In the structure, piezoelectric actuators attached to the columns and the beams were used for the microvibration control by bending moment control of them. The controller was designed using the H-infinity control theory. The tests showed that the smart structure could effectively reduce the 3D microvibration of the building model, and its applicability to floors and even entire buildings of semiconductor manufacturing factories having steel frame structures.

Application of Isolation to High-Rise Buildings: A Japanese Design Case Study through a U.S. Design Code Lens

Base isolation of high-rise buildings has been growing in popularity in Japan, yet it is uncommon in most of the world. While tall buildings already have long periods and thus lower input accelerations, the addition of isolation can decrease inter-story drifts and greatly decrease floor acceleration, protecting building content. By protecting building content, high-rises can be kept fully operational and occupiable after earthquakes. The Japanese design code has clearly outlined procedures for designing isolated high-rises, facilitating the implementation of isolation; however, other design codes—and specifically the U.S. code—make the adoption of isolation difficult for these buildings. Using a design representative of typical isolated high-rises in Japan, it is shown that while isolation is feasible under U.S. design levels, requirements are much more stringent, and some changes from the Japanese design would be required to make the design acceptable under the U.S. code.

A STUDY ON EFFECT OF CUSHIONS INSTALLED IN A SEISMICALLY ISOLATED HIGH-RISE STRUCTURE UNDER LONG-PERIOD GROUND MOTIONS

As a provision for excessive inputs, effect of cushions installed in a seismically isolated high-rise structure was studied. Results were as follows; 1) Though optimum parameters for various types of cushions were different on their restoring characteristics, effects of them were similar. 2) Common appropriate parameters against 3 kinds of inputs considered can be found. 3) Required force of cushions was not more than 5 % of the building weight. 4) Energy absorption of cushions was slightly effective. 5) The effect of cushions could be seen as increasing of 7-8 or 10-odd% of damping factor of seismic isolation layer.

Active Microvibration Control of Precision Manufacturing Facilities with Smart Structure Using Piezoelectric Actuator.

A smart structure was tested for active microvibration control of a 2-story steel frame building model of a 5×3×4Hm outer size and a 2 500 kg total weight which was excited by ambient ground vibration. In the structure, piezoelectric actuators attached to the columns and the beams were used for the microvibration control by bending moment control of them. The controller was designed using the H ∞ control theory. The tests showed that the smart structure could effectively reduce the three-dimensional microvibration of the building model, and its applicability to floors and even entire buildings of semiconductor manufacturing factories having steel frame structures.