In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers i...In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers in the field of construction. The experience from recent earthquakes of USA and Japan shows that brittle fracture of welded steel structure always starts from high stress zone with welded crack [1～5] . As backing bar for grooved weld on beam flange exists, artificial crack is formed because of lack of fusion at the root of flange weld. In this paper stress distribution of connection is computed with FEM, and stress concentration at the root of flange weld is also analyzed. Stress intensity factors (SIFs), K I, at the root of flange weld are computed in the method of fracture mechanics. The computation shows that stress intensity factor on bottom flange weld is obviously higher than that on top flange weld. It is proved by the fact that brittle fracture is liable to start at the root of bottom flange weld on actual earthquake [1,4] . Finally measures are brought forward to avoid fracture of weld structure against earthquake.展开更多
The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and ...The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and geometrical detail of steel plates contrast to the reference drawing of connection design in China. The research shows that the weld plays an important role in the design of connections. The welds connecting reinforced plates and beam/column flange and the plate geometry have direct influence on the performance of the connections reinforced with plates. The study is helpful to the application of design of steel moment-resisting connection with steel plates.展开更多
Stiffened and unstiffened fillet-welded tube-to-transverse plate connection details are widely used for mast-arm and base-plate connections for highway sign structures.However,due to repetitive wind loads,cyclic fatig...Stiffened and unstiffened fillet-welded tube-to-transverse plate connection details are widely used for mast-arm and base-plate connections for highway sign structures.However,due to repetitive wind loads,cyclic fatigue stresses are induced and they are the primary source of failure in welded connections at these locations.The resistance of fatigue critical details has been an on-going research topic because of limited experimental results and the variability in existing fatigue testing results.The main objective of this study is to evaluate fatigue resistance of fillet-welded tube connection details by utilizing the advanced fatigue tool in ANSYS Workbench platform.Finite Element(FE)models development and model validation using existing test data was presented.The resulting fatigue resistance from FE analysis was expressed in terms of fatigue life,fatigue damage,and fatigue safety factor to determine the fatigue performance of fillet-welded connections.Existing fatigue test data was grouped to perform a synthetic analysis and then analysis results were provided to determine input data and fatigue limit for the fatigue module.The local stress level at fatigue critical locations was evaluated using a static FE model for different number of stiffeners and boundary conditions.The results of this investigation provides fatigue resistance of fillet-welded connection details in the form of fatigue life,fatigue damage and safety factor for various connection parameters and structural conditions.展开更多
文摘In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers in the field of construction. The experience from recent earthquakes of USA and Japan shows that brittle fracture of welded steel structure always starts from high stress zone with welded crack [1～5] . As backing bar for grooved weld on beam flange exists, artificial crack is formed because of lack of fusion at the root of flange weld. In this paper stress distribution of connection is computed with FEM, and stress concentration at the root of flange weld is also analyzed. Stress intensity factors (SIFs), K I, at the root of flange weld are computed in the method of fracture mechanics. The computation shows that stress intensity factor on bottom flange weld is obviously higher than that on top flange weld. It is proved by the fact that brittle fracture is liable to start at the root of bottom flange weld on actual earthquake [1,4] . Finally measures are brought forward to avoid fracture of weld structure against earthquake.
文摘The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and geometrical detail of steel plates contrast to the reference drawing of connection design in China. The research shows that the weld plays an important role in the design of connections. The welds connecting reinforced plates and beam/column flange and the plate geometry have direct influence on the performance of the connections reinforced with plates. The study is helpful to the application of design of steel moment-resisting connection with steel plates.
文摘Stiffened and unstiffened fillet-welded tube-to-transverse plate connection details are widely used for mast-arm and base-plate connections for highway sign structures.However,due to repetitive wind loads,cyclic fatigue stresses are induced and they are the primary source of failure in welded connections at these locations.The resistance of fatigue critical details has been an on-going research topic because of limited experimental results and the variability in existing fatigue testing results.The main objective of this study is to evaluate fatigue resistance of fillet-welded tube connection details by utilizing the advanced fatigue tool in ANSYS Workbench platform.Finite Element(FE)models development and model validation using existing test data was presented.The resulting fatigue resistance from FE analysis was expressed in terms of fatigue life,fatigue damage,and fatigue safety factor to determine the fatigue performance of fillet-welded connections.Existing fatigue test data was grouped to perform a synthetic analysis and then analysis results were provided to determine input data and fatigue limit for the fatigue module.The local stress level at fatigue critical locations was evaluated using a static FE model for different number of stiffeners and boundary conditions.The results of this investigation provides fatigue resistance of fillet-welded connection details in the form of fatigue life,fatigue damage and safety factor for various connection parameters and structural conditions.
