Assessment of seismic behaviour of SMRFS with RBS connections by means of mixed-based state-space approach

With an intention to implement a reliable numerical implementation of the mixed‐based state‐space strategy for steel structural systems, the paper presents a thorough seismic analysis of steel moment resisting frames (SMRFs) with reduced beam section (RBS) connections. Firstly, a model of beam‐column element inclusive of material and geometric nonlinearities is efficiently utilized derived from appropriate force interpolation functions. Moreover, with the present formulation, non‐prismatic properties of RBS region can be considered without the necessity of heavy discretization of elements. Contribution of panel zone is taken into account by considering a nonlinear rotational spring as well. In addition, the extension of Wen‐Bouc model to capture material inelasticity is applied that is apparently superior to other constitutive behaviour when it leads to both a smooth hysteretic model and rather precisely well‐mannered state‐space depiction capable of conveying several hysteretic features. The state‐space approach is then employed where nodal forces balance and constitutive equations are solved simultaneously. Secondly, three‐dimensional finite element analysis is surveyed to validate proposed macro‐element model. Finally, a set of nonlinear static and transient analyses of four‐ and eight‐storey frames with and without RBS connections are fulfilled. Then, structural demand parameters used to assess the global and local response of designated frames.