| Budget Amount *help |
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2001: ¥5,900,000 (Direct Cost: ¥5,900,000)
Fiscal Year 2000: ¥8,300,000 (Direct Cost: ¥8,300,000)
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| Research Abstract |
Semi-rigid partial-strength beam-to-column connections composed from high-strength bolts and angles or endplates were studied in this research project Cydic loading tests and pseudo-dynamic tests were performed on various test structures inducting such a type of connections or semi-rigid column bases. Furthermore, a pendulum-type observatory termed 'steel swing' was developed and constructed, where a 15000kg mass was hung from a rigid steel frame and a specimen of building element can be inserted between the pendulum and the frame. Forced vibration test system and data acquisition system for seismic monitoring are also installed in the observatory.
Such semi-rigid frames have a disadvantage in general of too large deformation during moderate earthquakes, and appropriate stiffening may be needed. Pseudo-dynamic tests were performed on an existing flexible moment resisting frame that was built in the monitoring field. Low-yield-point steel shear panel dampers were used to stiffen the mode
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l structure. Several ground motions recorded in the past events at the site were used as input excitations in the pseudo-dynamic tests. (The events were observed on October 4, 1985, on June 24, 1986, on December 17, 1987, and on September 11, 1996.) The effects of response mitigation by the dampers were examined from the test results. As for semi-rigid column bases, a rectangular hollow section steel column was supported by an exposed column base that consists of anchor bolts and a base plate, and installed in the pendulum-type observatory to observe stiffness and damping during moderate seismic events. Seismic monitoring was started in 2001 after preliminary vibration tests, and responses of column base to eighteen events were successfully recorded.
Based on these test and monitored data, how to classify various semi-rigid connections suitably in the design procedure was studied, and also a simple method for evaluating yield strength, maximum strength, rigidity, and deformation capacity were proposed. An appropriate design procedure of steel structures with semi-rigid partial-strength connections was proposed including a combination with other earthquake resisting elements such as dampers. Less
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