This study describes detailed numerical investigations into the inelastic cyclic response of beam-column assemblages of moment frames incorporating reduced beam section (RBS) welded connections. Detailed three-dimensional nonlinear finite element procedures are validated against results of selected tests from a series of three large scale experimental tests. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response, a number of numerical investigations are carried out. Particular emphasis is given to the influence of key material and geometric parameters on the balance of energy dissipation between the panel zone and the reduced beam zones. The results of the parametric studies enable direct assessments regarding the contribution of the main dissipative components to the inelastic performance of RBS moment connections, as a function of the main geometric and material parameters. Key observations from the numerical simulations, which are relevant for the design and assessment for such configurations are highlighted within the discussions with particular focus on European seismic design guidelines.