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Behaviour of link-to-column connections in steel eccentrically braced frames
Published in Federico M. Mazzolani, Stessa 2003, 2018
T. Okazaki, M.D. Engelhardt, M. Nakashima, K. Suita, K.C. Tsai
The performance of EBF link-to-column connections is being studied through large-scale experiments. Based on tests completed to date, the following conclusions and observations are made: The specimens employing link-to-column connection details based on pre-Northridge practices did not allow links of any practical length to develop the inelastic deformation capacity prescribed in the code. Failure of these connections, regardless of link length, is controlled by fracture in the link flange-to-column flange connection.The combination of modifications in welding practices and the use of improved weld access hole geometry per FEMA (2000) improves the connection performance by a small margin. These modifications alone are not sufficient to permit links to achieve code prescribed rotations.The failure mode of shear links may be governed primarily by fracture along the link web-to-column flange connection. This is in contrast to moment frame connections, where fracture and local buckling in the beam flange govern failure. Hence, a design modification, significantly different from those developed for moment frame connections, may be required for the improvement of link-to-column connections with shear links.None of the specimens achieved little more than half of the code prescribed rotation capacity. There is a clear need for further research to develop a reliable design for link-to-column connections.
Uncertainty assessment of field weld connections and the related effects on service life of steel buildings
Published in Structure and Infrastructure Engineering, 2019
Heui-Yung Chang, Chien-Kuo Chiu
Figure 3a gives the macrostructure of a steel weld and specimen location. Figures 3a and b illustrate the microstructures of steel welds with and without rust on the welding surfaces. Figures 4a and b summarises the results of the Vickers’ hardness tests and Charpy impact energy tests. Figure 5a shows the configuration of a 6.25-mm diameter round bar with a notch in the HAZ. The notched specimens were taken from the cruciform joints using the SMAW process. The welded over rust is considered to include more porosity in the HAZ. The added notch allows studying the degradation caused by the increased porosity. Figures 5b and c provides the details of two notch shapes. The variation in notch shape allows studying the stress concentration caused by geometric discontinuities such as the toe of the bottom flange weld access hole. Figures 6a and b shows the stress–strain curves obtained for specimens with different surface treatments, notch shapes and loading types.