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A platform for research: civil engineering, architecture and urbanism
Fatigue properties of practical-scale unbonded braces
Damages inflicted on beam ends of steel structure buildings during the big earthquake in the Hanshin-Awaji area in January, 1995 aroused interest in a damping method (damage controlling method) whereby the main structure portion is kept at the elastic region by use of hysteresis dampers behaving plastically from low force input levels. This paper describes studies on performance limits of unbonded braces as hysteresis dampers based on tests on fatigue properties of practical-scale unbonded braces. Tests showed that the number of cycles for causing materials failure was approximately 200 when the equivalent story drift angle was 1/100, the result of which was proof enough that the braces have good fatigue properties in consideration of accumulated plastic deformation factor. This paper also shows that the same fatigue properties can be obtained when different steel grades (JIS SN400B, and Nippon Steel's specifications LYP100 and LYP235) are used for the cores of the braces. From comparative studies with materials fatigue tests and model tests of the brace core, the fatigue properties of the practical-scale unbonded braces were found to decrease due to factors such as local buckling of the brace core. A formula is proposed herein for expressing a fatigue curve in consideration of strain concentration and it is demonstrated that the proposed formula can estimate fatigue life of the braces. (VDEh)
Fatigue properties of practical-scale unbonded braces
Damages inflicted on beam ends of steel structure buildings during the big earthquake in the Hanshin-Awaji area in January, 1995 aroused interest in a damping method (damage controlling method) whereby the main structure portion is kept at the elastic region by use of hysteresis dampers behaving plastically from low force input levels. This paper describes studies on performance limits of unbonded braces as hysteresis dampers based on tests on fatigue properties of practical-scale unbonded braces. Tests showed that the number of cycles for causing materials failure was approximately 200 when the equivalent story drift angle was 1/100, the result of which was proof enough that the braces have good fatigue properties in consideration of accumulated plastic deformation factor. This paper also shows that the same fatigue properties can be obtained when different steel grades (JIS SN400B, and Nippon Steel's specifications LYP100 and LYP235) are used for the cores of the braces. From comparative studies with materials fatigue tests and model tests of the brace core, the fatigue properties of the practical-scale unbonded braces were found to decrease due to factors such as local buckling of the brace core. A formula is proposed herein for expressing a fatigue curve in consideration of strain concentration and it is demonstrated that the proposed formula can estimate fatigue life of the braces. (VDEh)
Fatigue properties of practical-scale unbonded braces
Ermüdungseigenschaften von praktisch nicht verbundenen Streben
Nakamura, H. (author) / Maeda, Y. (author) / Sasaki, T. (author) / Wada, A. (author) / Takeuchi, T. (author) / Nakata, Y. (author) / Iwata, M. (author)
Nippon Steel Technical Report ; 51-57
2000
7 Seiten, 14 Bilder, 5 Tabellen, 13 Quellen
Article (Journal)
English
Stahlbau , Gebäude , Stütze , Ermüdung , Dämpfung , mechanische Hysterese , plastische Verformung , Berechnung , Versagen , Baustahl
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