2007 Fiscal Year Final Research Report Summary
A study on the ultimate performance of steel high-rise buildings subjected to long period seismic ground motions which are estimated during severe earthquakes
| Project/Area Number |
18560557
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
YAMAZAKI Shinji Tokyo Metropolitan University, Graduate School of Urban Environmental Sciences, Prof. (30264592)
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| Co-Investigator(Kenkyū-buntansha) |
MINAMI Susumu Tokyo Metropolitan University, Graduate School of Urban Environmental Sciences, Assistant Prof. (00219693)
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| Project Period (FY) |
2006 – 2007
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| Keywords | steel beam / beam-end connection / local buckling / cyclic loading / monotonic loading / energy absorption capacity / cumulative plastic deformation / random loading |
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| Research Abstract |
It is conjectured that in the Tokyo Metropolitan, Osaka and Nagoya areas seismic ground motions with large power over a long period component caused by destructive deep-sea earthquakes such as Tokai, Tonankai or Nankai earthquakes, which are expected to occur in the near future, will continue over several minutes. This study aims at making clear the critical performance of steel high-rise buildings in cases where they are subjected to long period seismic ground motions which are estimated during severe earthquakes.
The seismic performance of steel structural frames is limited by the collapse of beams in most cases. In this study, in order to make clear the behavior of beams and their critical performance cyclic loading tests were carried out using beam specimens with about the same width-thickness ratio as well as with the same end connection details as those which are used in existing high-rise frames. In all, 30 specimens were used in the tests covering 8 different types. For the purp
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ose of making clear the effects of the loading hysteresis on the energy absorption capacity, several types of loadings each with different amplitudes and cyclic patterns were carried out for the specimens which have the same shapes.
The results obtained from this study can be summarized as follows :
With regard to the critical performance of beams whose maximum strength is determined by the fracture of flanges at the beam end connection
1)The fracture behavior can be divided into the following two types.
Type (F1): The specimen fractures after cracks expand from the center of the width of the flange weld and the sectional area ratio decreases to 70 80%.
Type (F2) : The specimen fractures after cracks expand from the edge of the width of the flange weld and the sectional area ratio decreases to 90 95%.
2)The maximum strength ratio in the case of the cyclic loading decreases with an increase in the number of the plastic cyclic loading. However, the decreasing degree in the case of type (F2) is smaller than that for (F1).
3)The maximum strength ratio in the case of the monotonic loading can be estimated using the existing method.
4)The energy absorption capacity in the case of the monotonic loading can be estimated using the maximum strength ratio in the case of the monotonic loading.
5)A method for estimating the lowest limit value of the energy absorption capacity in the case of the cyclic loading using both the energy absorption capacity for the monotonic loading and the effective number of the cyclic loading has been derived.
With regard to the critical performance of beams in which the maximum strength is determined by the local buckling
1)The energy absorption capacity in the case of the monotonic loading can be estimated using the method prescribed in the existing reference.
2)A method for estimating the lowest limit value of the energy absorption capacity in the case of the cyclic loading using both the energy absorption capacity for the monotonic loading and the effective number of the cyclic loading has been derived. Less
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Research Products
(8 results)
