SUMMARYThe Active Variable Stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural characteristics, such as stiffness of a building, to establish a non-resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate practical data and investigate them, a building has been constructed as a trial. This paper describes the applied system, the control algorithm, verification of stiffness selection, results of tests for verifying system characteristics, some observed earthquake records and simulation analyses. Responses in controlled and uncontrolled states have been compared to show the effectiveness of the proposed system.
SUMMARYThe active variable sti ness (AVS) system is proposed as a seismic response control system. It actively controls structural sti ness of a building to establish a non-resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate and analyse practical data, a building was constructed as a trial structure about ten years ago. This paper describes the control algorithm, the applied system, some observed earthquake records, veriÿcation of control e ectiveness based on simulation analyses, and some issues concerning system maintenance. Through earthquake observations, it was conÿrmed that the system could select the appropriate sti ness that assures a non-resonant state, which results in a minimum response.
The measurement of cracks in concrete surfaces is a procedure undertaken to diagnose deterioration and the prospective life of concrete structures. The authors have been studying a measuring system which uses computer image processing to reduce labor requirements and increase reliability. In this study crack data were first defined and then a data processing method which combines general-purpose image processing techniques with artificial intelligence theory was developed in order to extract crack patterns from concrete surface data and measure crack length, direction and width. It was found that crack measurements can be processed automatically or with the aid of simple manual operations.
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