2003 Fiscal Year Final Research Report Summary
Nonlinear Dynamic Response and Seismic Performance of Steel Towers of Cable-Stayed Bridges under Great Earthquake Ground Motion
| Project/Area Number |
14550473
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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 |
構造工学・地震工学
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| Research Institution | Hokkaido University |
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Principal Investigator |
HAYASHIKAWA Toshiro Hokkaido University, Grad.School of Eng., Assoc.Prof., 大学院・工学研究科, 助教授 (90002302)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Cable-stayed bridges / Steel towers / Seismic performance / Nonlinear dynamic response analysis / Level 2 earthquake / Initial imperfections / Energy dissipation system / Fiber model |
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| Research Abstract |
A finite element procedure based on total Lagrangian formulation for the nonlinear dynamic analysis of steel tower cable-stayed bridge under three dimensional great earthquake ground motion is carried out. From the peiformed investigations and discussions, the following conclusions can be summarized.
(1)The effectiveness of the horizontal beam position on tower axial force dynamic response is assured. The change of horizontal beam height from that of the original tower toward tower top reduces the compressive and tensile axial forces at tower base.
(2)The inverted V-type has the largest axial force response, where the maximum compressive and tension axial forces are about 4.70 and 2.55 times of the gravity loads, respectively. The large negative reaction makes the problem that the anchor bolts may fail in the lift up and the safety of the tower should be considered.
(3)The proposed energy dissipation system demonstrates its capability and effectiveness in reducing structural dements force
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s and controlling tower maximum displacement through its capability achieving the concentration of inelastic behavior at tower horizontal beam and keeping the rest of the structure elastic behavior as yield level decreases. The post-yield buckling capacity should be considered in the design of tower structures.
(4)The effect of vertical ground motion has highly dependence on damping scheme. The Rayleigh's damping is more effective in high frequency range, which leads to slightly effects of the vertical ground motion on tower dynamic response. The Royleigh's damping could be recommended for conservative nonlinear seismic response of high-rise towers.
(6)The low yield steel material could add damping primarily by material hysteresis and increase tower flexibility as the horizontal beam early attains, in terms tower structural system ability to reflect a portion of earthquake input energy increase. The energy dissipation system become effective in energy absorption through the horizontal beam.
(7)The massive rigid foundation actives the high frequency translation motion of the input ground motion and generates foundation-rocking responses. The predominant contribution to the vertical response at footing base corner from the massive foundation rocking rather than from the vertical excitation. The permanent settlement is found to be less significant. Less
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