Moment–rotation behavior of bolted top–seat angle connections

Bolted top and seat angle connections are mainly designed to sustain gravitational loads of simply supported steel beams. However, the inherent flexural resistance of top–seat angle connections may not be ignored when an accurate analysis of semi-rigid steel frames is desired. The goal of the current study is to find a new moment–rotation relation to estimate the behavior of connections of this type. Semi-analytical equations are proposed for this purpose based on the data bank, which is created using finite element simulation. Several refined 3D finite element models were created based on the previous experimental studies and their accuracy is examined through a comparison to test results from previous studies and other published numerical models. The presented new semi-analytical method covers some deficiencies of the previously proposed methods, and the accuracy of this approach is evaluated comparing its results with those of the other methods. The study is further extended, and the effect of axial force on the moment–rotation response of such connections is studied. This study shows that the axial tension load reduces the initial connection stiffness and moment capacity. The applicability of the presented method is evaluated, and it is shown that the model has the potential to estimate connection moment–rotation behavior under combined axial tension and moment loading.