1994 Fiscal Year Final Research Report Summary
A study of design procedure for stability of steel structures
| Project/Area Number |
03402041
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
土木構造
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| Research Institution | Saitama University (1994)
The University of Tokyo (1991-1993) |
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Principal Investigator |
NISHINO Fumio Saitama University, Graduate School of Policy Science, Professor, 大学院・政策科学研究科, 教授 (90010777)
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| Co-Investigator(Kenkyū-buntansha) |
IWAKUMA Testuo Tohoku University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (60120812)
HORII Hideyuki University of Tokyoy, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10181520)
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| Project Period (FY) |
1991 – 1994
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| Keywords | steel frames / effective length / design / ultimate strength / eigenvalue analysis / finite displacement analysis / equivalent initial imperfection / equivalent reduced elastic modulus |
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| Research Abstract |
In the present design codes, the determination of effective length is by no means easy and clear. Against this background, three methods to evaluate ultimate strengths of steel frames without using effective length have been proposed in the present study.
1) It is proposed that effective lengths are obtained trough the eigenvalue analysis of tangent stiffness matrix. When a small compressive force is acting, the proposed method has been known to overstimate effective length. It has been pointed out however that this trouble can be solved simply by increasing the compressive force.
2) A design method based on nonlinear structural analysis has been proposed. However, since full nonlinear analysis is not practical, only geometrical nonlinearity is taken into account directly in the analysis. The other factors such as residual stresses are considered in the form of equivalent initial imperfection.
3) For some structures, it would be difficult to give equivalent initial imperfection. Because of this, a method, in which factors such as residual stresses are considered in the form of equivalent reduced elastic modulus, has been proposed. The equivalent reduced elastic modulus has been determined as a function of internal forces.
The effectiveness of these methods have been demonstrated by solving example problems. All these methods are a clear-cut numerical procedure. It is therefore possible to establish a more rational design procedure with these method.
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