Performance of circular CFST column to steel beam joints with blind bolts

This paper investigated performance of circular concrete filled steel tubular (CFST) column to steel beam joints with blind bolts. Four monotonic loading tests were conducted on the flush or extended end plate joints to circular CFST columns with blind bolts. A nonlinear finite element (FE) modeling study on the circular CFST column joints under static loading was developed, in considering contact interaction, material model and analysis steps etc. The accuracy of the FE models was examined by the experimental results in the field of moment-rotation relationships and failure modes. Massive parametric analysis was utilized to explore the effects of axial level, bolt diameter and anchorage length ratio etc. on the ultimate moment capacity and the initial stiffness of the novel connections. The test and 3D elastoplasticity numerical analysis results indicated that the circular CFST column joints could be regarded as semi-rigid and partial or full strength. Effective methods including anchorage and stiffening strengthening were also discussed in this paper to promote the engineering application of circular CFST column joints with blind bolts.