Mechanical behavior of the bottom flange bolted and top flange welded joints between concrete-filled steel tubular columns and steel beam
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Abstract:
In order to study the mechanical behavior of the bottom flange bolted and top flange welded joints with vertical stiffener between concrete-filled steel tubular columns and H-shaped steel beams, three joint members were designed and manufactured, and their pseudo-static tests were carried out with the connection mode of upper flange and the cross-section size of the beam as test parameters. At the same time, DSCM (digital speckle correlation method) measurement system was introduced to measure the strain in the core area of the node with non-contact high precision. The results show that the main damage locations of the components are near the weld due to the quality of the weld seam. The damage of the bottom flange bolted and top flange welded joints occurs at the weld joints of the upper flange and the outer ring plate of the beam, while the damage of the full bolt joints occurs at the weld joint between the inner diaphragm and the column. The core area deformation of the bottom flange bolted and top flange welded joints is smaller than that of the full bolt joint, suggesting that it is more in line with the criterion of "strong column and weak beam". It can be concluded that the load transfer between beam and column is mainly through the outer ring plate, but the ductility of full-bolted joints is significantly better than that of the bottom flange bolted and top flange welded joints due to the slippage of bolts and fewer welding defects. Moreover, beam cross-section size and joint connection mode have a greater impact on the stress performance and strain distribution in the core area, and the principal strain and shear strain nephogram in the core area develop obliquely at 45 degrees.
