Investigations and Improvement of the Joint Between Narrow Steel Beams and CFST Columns

In this paper, the forked-web joint configuration was introduced first, in order to transfer the shear and moment forces better and avoid the local buckling problem that usually happens in narrow steel beams and concrete-filled steel tubular (CFST) column joints. Experiments including three specimens of that joint were then conducted, considering different axial compression ratios of the column. The test results indicated that no failure phenomenon happened to the proposed joint when the equivalent rotational angle was no more than 1/50. However, the final failure mode of each specimen was still local buckling and tearing failure of beam flanges due to the excessively large stress. Finally, based on the tests and FEA results, a corresponding improvement, including a single-web configuration with U-shape and triangular stiffeners, was thus brought forward and numerically verified in terms of rotational stiffness, failure mode, and the hysteretic curve. The FEA results revealed that the rotational stiffness of the proposed single-web joint with triangular stiffeners for beams and U-shape stiffeners for CFST columns efficiently increased from 0.87 to 3.83, and it was almost twice that of the narrow beam-column joint with internal horizontal diaphragms. Moreover, the previous undesirable tearing failure mode was finally avoided by adopting high-strength steel Q550 for the joint beam part.