Rotational demand and capacity of conventional single-plate shear connections subjected to gravity loading

This study aims to investigate the adequacy of the ductility requirement presented in the 15th edition of AISC Steel Construction Manual for conventional single-plate (CSP) connections when the threads of the used bolts are excluded from the shear plane (i.e., using X-bolts). For this purpose, by changing different parameters, 72 specimens were designed in accordance with the AISC Manual. All specimens were analyzed based on finite element (FE) method using ABAQUS software. FE results indicated that the most effective parameters which affect the connection rotational demand are loading type and beam length-to-beam depth ratio while connection rotational capacity is mostly affected by the number of bolts, beam depth and bearing strength of beam web/shear tab. To make a more accurate judgment about connection ductility, first, the existing equation for estimating rotational demand, usually leading to a non-conservative prediction, was modified. Then, using the FE results, three predictive models for connection rotational capacity was proposed. Comparing these models showed that the one which was developed on the basis of the artificial neural network is of the highest level of accuracy. Finally, using Monte Carlo method, a reliability analysis was conducted which showed that the ductility requirement of AISC Manual can be too conservative in most cases when the number of bolts exceeds five.