Moment-rotation relationship of blind bolted connections for HSS columns

Typical extended end-plate connections used in moment resisting steel frames with Hollow Structural Section (HSS) columns will generally exhibit a certain degree c f flexibility. The actual response of such frames cannot be realistically assessed, unless the connection flexibility is incorporated in the analysis. This requires the development of moment-rotation relationships capable of representing connection response. The objective of this work is to develop an analytical model for such connections capable of simulating its behaviour in terms of its moment-rotation relationship, so that it can be used in the determination of the overall frame response. The model evaluates the main connection parameters such as its initial stiffness and plastic moment capacity on the basis of few secondary parameters obtained from test results. The HSS' column flange is modelled on both the tension and the compression sides of the connection because of its major contribution to the connection's rotation. The accuracy of the analytical model was examined by comparing the model results with experimental measurements. It was found that the model predicts the connection rotation with reasonable accuracy at different levels of loading. A numerical example is provided to illustrate how the connection model can be applied in design..