A reliable cyclic envelope model for partially-restrained steel beam-column bolted T-stub connections based on experimental data

The utilization of partially-restrained (PR) steel beam-to-column bolted T-stub connections offers a promising avenue for enhancing the efficiency and resilience of steel structural systems by reducing material consumption and facilitating post-hazard rehabilitation of connection components. However, the practical application of PR Tstub connections faces challenges due to the lack of comprehensive design guidelines. Specifically, in the context of performance-based seismic design for structural systems featuring PR T-stub connections, the accurate characterization of the cyclic envelope is pivotal. Presently, the availability of dependable cyclic envelope models tailored to PR T-stub connections is limited, with existing models facing various limitations. In response to these challenges, this study aims to pioneer a more dependable envelope model capable of mitigating the shortcomings of existing models. To achieve this objective, a comprehensive database comprising experimental data from steel beam-to-column assemblages with T-stub connections subjected to cyclic loading is compiled. These assemblages feature T-stubs either cut from hot-rolled sections or fabricated by welding plates, while the connected beams and columns are hot-rolled members. A four-stage multi-linear cyclic envelope is then developed. Particular attention is given to determining the two key characteristics of PR T-stub connections: maximum strength and initial rotational stiffness. The accuracy and robustness of the developed envelope model are rigorously assessed through comparisons with both experimental results and predictions from existing envelope models.