Azizinamini and Prakash 1992

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A through-beam connection detail was considered both analytically and experimentally in this research. The through-beam connection detail prevents the transfer of large beam shear forces directly to the steel tube. This helps to prevent the steel tube from pulling away from the concrete core. Additionally the through-beam connection detail eliminates the need for welding thick connection elements to relatively thin steel tubes, which results in lower residual stresses then direct welding. A behavioral model was developed and the force transfer mechanism of the through-beam connection detail was identified. A tentative design approach was suggested.

Analytical Study

The qualitative behavior of the through-beam connection detail was considered using two- and three-dimensional non-linear finite element methods. Two cases were analyzed; in the direct connection detail, the beam was directly connected to the steel tube, while in the through-beam connection detail, the beam was passed completely through the column.

In the direct connection detail, very high stress concentrations occurred in both the steel tube and the concrete in the vicinity of the connection. Additionally, the steel tube separated from the concrete, resulting in large tensile stresses in the tube wall. Significant tensile stresses developed in the concrete around points modeling the shear stud locations.

When the through-beam connection detail was examined, considerably lower stresses were observed in the detail compared to the direct connection detail. Significant reductions were noted in the magnitudes of the tensile pull-out stresses in the steel tube, the compressive stresses in the steel tube, and the tube separation from the concrete at the joint interface. The portion of the steel tube between the beam flanges acted like a stiffener by mobilizing a concrete compression strut which assists the beam web inside the steel tube in absorbing shear. A compressive force block was created by the beam flanges pressing against the concrete on top of and below the flanges.

References

Azizinamini, A., Prakash, B., Prishtina, B., and Salmon, D. C. (1992). “Through Connection Detail for Composite Columns in Highrise Buildings,” Proceedings of the SSRC Annual Technical Meeting, Pittsburgh, Pennsylvania, April 6-7, 1992, Structural Stability Research Council, Bethlehem, Pennsylvania, pp. 225-236.