| Project/Area Number |
14550483
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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 | Tokai University |
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Principal Investigator |
NAKAMUA Shunichi Tokai University, Dept.of Civil Engineering, Professor, 工学部, 教授 (40297198)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | corrosion / suspension bridge cables / remaining strength / hydrogen embrittlement / fatigue strength / zinc coating / surface roughness / cable-stayed bridge cables |
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| Research Abstract |
Cables and hanger ropes of old suspension bridges often suffer from a corrosion problem. Corroded galvanized steel wires on different corrosion levels were produced, and their mechanical properties and remaining strength were investigated. Actual tensile strength of corroded wires did not decrease, whereas elongation, torsional and fatigue strength decreased sharply. Amounts of hydrogen absorbed in corroded wires were measured showing that it did not reach a level to cause hydrogen embrittlement. The surface of corroded wires is uneven and this surface roughness seems to decrease ductility of corroded wires.
Broken wires and suspenders cut from an old suspension bridge were investigated. Their tensile strength, elongation and chemical composition were almost the same as those of current bridge wires. However, the removed wire was curved, indicating that high residual stresses existed in the wires in service. The fracture surface was similar to that caused by corrosion fatigue rather than by hydrogen embrittlement. It was estimated that the wires fractured by mixed effects of corrosion, cyclic stresses, high residual stresses, hydrogen and fretting.
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