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Hitoshi KUWAMURA, Jun IYAMA, Yukio YOKOYAMA
1997 Volume 4 Issue 16 Pages
1-16
Published: December 25, 1997
Released on J-STAGE: July 04, 2011
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Full-scale fracture test was done for beam-to-column welded connections which were fabricated on the basis of current practice of tall buildings in Japan. Three different modes of brittle fracture were observed, which are named divot pull-out fracture of column flange, scallop root fracture of beam flange, and web-fillet root fracture of beam flange. The cumulative ductility prior to the fracture is greater than 20 which seems enough to resist a severe earthquake. Such satisfactory ductility is attributed to low yield-ratio, rich ductility, and ample notch-toughness of the steel newly specified in JIS-1994 as well as to good quality control in welding process.
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Masahiro SAKANO, Nobuhiko KISHIGAMI, Tsuyoshi ONO, Ichizo MIKAMI
1997 Volume 4 Issue 16 Pages
17-26
Published: December 25, 1997
Released on J-STAGE: July 04, 2011
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In the 1995 Hyogokenn-Nanbu Earthquake, a brittle fracture occurred at steel pier beam-column joint without web corner fillet. Then we conducted a super-low-cycle fatigue experiment in order to investigate the cracking behavior in the steel pier beam-column joint without web corner fillet. Cracks with the surface length of 2-i imm were detected in a few cycles at the fillet weld toe on the column flange, which was fractured after more few cycles. Fatigue life of steel pier beam-column joint specimens without web corner fillet, was reduced to be about a half of that with web corner fillet with the radius of 20mm.
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(Parti :Test Plan and Pilot Test)
Kazuo INOUE, Isao KOHZU, Motohide TADA, Eiji TATEYAMA, Mototsugu TABUC ...
1997 Volume 4 Issue 16 Pages
27-42
Published: December 25, 1997
Released on J-STAGE: June 28, 2010
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This paper presents the background, objectives, organization, and outline of a comprehensive experimental project conducted by the Steel Committee of the Kinki Branch of the Architectural Institute of Japan. The objectives are to re-evaluate the plastic deformation capacity of beams in moment resisting frames and to offer improved connection details for better ductility. A total of 86 full-scale beam-column subassemblages were tested, with major test parameters as the grade of steel, type of connection, type of connection details, type of run-off tabs, loading rate, and temperature. Details of those major parameters are explicated, and results of preliminary tests applied to 3 specimens are described. The preliminary tests indicated improved ductility when modified connection details are adopted.
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(Part 2:Test for Specimens of Shop-Welding Type with a Beam Section of H-500×200×10×16)
Mototsugu TABUCHI, Koji MORITA, Tsuyoshi TANAKA, Teruyasu KAIVIBA
1997 Volume 4 Issue 16 Pages
43-58
Published: December 25, 1997
Released on J-STAGE: June 28, 2010
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This paper presents the results of tests conducted for beam-column subassemblages having a beam section of H-500×200×l0×lb (Grade : SS400) and jointed by a method of shop-welding type. A total of 27 specimens were tested, with the type of connection details, type of run-off tabs, method of welding, thickness of through diaphragm, and temperature as test variables. Major findings include that (1) the specimens with improved scallops are superior in plastic deformation capacity to those with conventional scallops; (2) specimens with welding of one path per layer and steel run-off tabs show lower plastic deformation capacity, in which cracks initiated from the toe of weld caused brittle fracture along the heat affected zone of weld.
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Masayoshi NAKASHIMA, Eiji TATEYAMA, Kiyotaka MORISAKO, Keiichiro SUITA
1997 Volume 4 Issue 16 Pages
59-74
Published: December 25, 1997
Released on J-STAGE: July 04, 2011
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This paper presents the results of tests conducted for beam-column subassemablages having a beam section of H-600×250×12×25 and joined by a method of shop-welding type. A total of 40 specimens were tested, with the type of connection details, type of run-off tabs, method of welding, and loading rate as primary test variables. Major findings include that (1) specimens whose beam-to-diaphragm weld had a weld pass sequence of one path per layer failed early; (2) ductility capacity was generally larger for flux run-off tabs than for steel run-off tabs because of early crack growth observed in specimens with steel run-off tabs; (3) plastic deformation capacity remained relatively unchanged regardless of the type of connection details; and (4) dynamic loading did not reveral visible decrease in plastic deformation capacity compared to quasi-static loading, with a possible reason identified as significant temperature rise observed in dynamic loading.
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(Part 4 : Test for Specimens of Field-Welding Type with a Beam Section of H-600×250×12×25)
Motohide TADA, Isao KOHZU, Yoshiomi MARUOKA, Fumiyoshi MINAMI, Kazuo I ...
1997 Volume 4 Issue 16 Pages
75-87
Published: December 25, 1997
Released on J-STAGE: March 01, 2011
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This paper presents the results of 16 tests applied to specimens having a beam section of H - 600×250×12×25 (SN490B). A field-welding connection was adopted, in which beam flanges and web were welded and bolted to the column, respectively. Test parameters were (1) type of connection details (conventional vs. modified), (2) type of run-off tabs (steel tab vs. flux tab), and (3) thickness of through-diaphragm plates (28 mm vs. 32 mm). Specimens with modified details showed larger ductility than those with conventional details, and specimens with steel run-off tabs were also larger in ductility than those with flux run-off tabs. The effect of the thickness of diaphragm plates on ductility was found at most secondary.
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(Part 5 : Discussion on Fracture Property and Plastic Deformation Capacity)
Kazuo INOUE, Isao KOHZU, Keiichiro SUITA, Motohide TADA, Eiji TATEYAMA ...
1997 Volume 4 Issue 16 Pages
89-104
Published: December 25, 1997
Released on J-STAGE: June 28, 2010
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This paper discusses the influence of connection details on fracture property and plastic deformation capacity of steel wide-flange beams connected with steel columns. New types of scallop adopted in the present study generally improved the plastic deformation capacity of beam-to-column joints. This was demonstrated by the fracture mode : New types of scallop inhibited brittle fracture from scallop bottom, although it was frequently observed in the conventional type of scallop. Nevertheless, the degree of improvement depends on the material property of steel beams. Most of beam-to-column connections with new types of scallop exhibited fracture from weld start/end in the beam flange. In this case, quality of welds plays an important role in ductility capacity of connections. Weld pass sequence of 1- path per layer and the use of flux run-off tabs potentially decrease ductility capacity, which is attributed to lower quality of welds and incidence of weld defects in case of inexperienced application of flux run-off tabs.
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Takeshi NAKAMURA, Tanfang FANG
1997 Volume 4 Issue 16 Pages
105-111
Published: December 25, 1997
Released on J-STAGE: July 04, 2011
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The elastic-plastic behavior of concrete filled steel columns subjected to concentrical or eccentrical compression is analyzed under high temperature. The new analytical model and design formulas of columns in the fire are proposed. In the new model, the strength of steel tube is negelected, because the unprotected outer steel tube loses the strength and the stiffness gradually in the fire. The concrete is divided . into two parts in the model, one is an un-effective portion near the edge of the column-section. In this portion, the strength of concrete is neglected. The other is an effective inner portion. It is assumed that the filled concrete maintains the strength under room temperature in the effective portion. On the basis of this simple model, a simple but rational design formula of columns is proposed.
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Masahir KUBO, Norihisa SUGIYAMA, Hirotaka KITAHORI
1997 Volume 4 Issue 16 Pages
113-120
Published: December 25, 1997
Released on J-STAGE: June 28, 2010
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This paper presents experimental results on the straightening effects of steel beams failed by lateral-torsional buckling. Eight different welded I-sections were tested under a central concentrated load at a simply supported beam. In the first buckling tests loads were applied until unloading region of approximately 60% of the maximum moment for each beam. After the residual deformations were straightened by press working, the second buckling tests were carried out under same loading conditions. The ultimate strength and the rotation capacity were compared with the two cases to investigate their recovery.
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Xiaojing HUANG, Yasuharu FUKASAWA, Miyoshi OKAMURA
1997 Volume 4 Issue 16 Pages
121-128
Published: December 25, 1997
Released on J-STAGE: July 04, 2011
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While a train passing through a bridge made up of thin-walled steel members, the local vibrations of the members cause structural noises and fatigue failure at the joined parts. Such kind of dynamic behaviour is treated as instability problem of local vibration under periodic axial thrust and bending moment in our present research. Higher order finite strip method and harmonic balance method has been applied. We have known that periodic axial thrust creates main unstable regions of the simple parametric resonance, periodic bending moment creates main unstable regions of the combination resonance and these two kinds of force acting together creates both of the unstable regions.
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Shigeru KAYANO, Toshimasa SAITOH, Osamu AZUMAYA, Hiroshi TANG
1997 Volume 4 Issue 16 Pages
129-141
Published: December 25, 1997
Released on J-STAGE: June 28, 2010
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A simple analysis model with two or four degrees of freedom was applied to a multi-span continuous girder bridge with an ants-seismic bearing in order to clarify its dynamic elasto-plastic behavior during an earthquake. The same structure was then nalyzed using a non-linear time history response method with a multiple degree of freedom, using a more detailed frame analysis model. When the dynamic behaviors obtained from both analysis methods were compared, no significant difference was observed between both response values. Thus, the effective application of this analysis method based on a simple analysis model to the mults-span continuous girder bridge was demonstrated.
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