1998 Fiscal Year Final Research Report Summary
Study on Dynamic Collapse of Structure due to Impact Load
| Project/Area Number |
09650123
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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 |
Materials/Mechanics of materials
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| Research Institution | Setsunan University |
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Principal Investigator |
KUROKAWA Tomoaki Setsunan Univ., Dept.Mech.Engng., Professor, 工学部, 教授 (80127076)
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| Co-Investigator(Kenkyū-buntansha) |
IMAIDA Y Doshisha Univ., Dept.Mech.Engng., Professor, 工学部, 教授 (20066260)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Impact / Buckling / Tube / Collapse / Earthquake |
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| Research Abstract |
1. Behavior of collapse of tube due to axial load
Axisymmetric buckling of steel pipe bridge pier was found in structure failure due to the Great Hanshin Earthquake in 1995, Japan. To investigate the cause of this type of failure, model experiments using small size (approximately 1/50) but same material(SS400 steel) tube specimens as real structure were carried out. Radius to thickness ratios R/t of tubes were taken to be in very wide range of 20 to 120 containing the value of real structure R/t=60. The following results were obtained,
(1)Axisymmetric buckling is easy to occur in the range of R/t between 25 and 100.This limit is different from predicted one before.
(2)The critical buckling stress of tube of R/t nearby 60 is 250 to 350 MPa.
2. Possibility of axisymmetric buckling due to vertical ground motion
To examine the possibility that axisymmetric buckling of steel pipe pier might have occurred due to not horizontal but vertical ground motion, response analyses of lumped-mass and spring system for vertical ground motion of various rise times were curried out. It was found the axial stress in pier was possible to exceed 25OMPa for vertical ground motion of shorter rise time than 0.Ols. Although any sharp spike was not recorded in real seismic acceleration meter, steep rising ground motion around 0.Ols might have occurred because higher frequency vibrations than 30Hz were cut off through low-pass filter. Therefore the possibility that axisymmetric buckling of steel pipe pier was generated due to steep vertical ground motion can not be denied.
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