A new type of the strengthened strategy for the limited anti-collapse capacity of extended end-plate connections (EEC) is proposed. Bending stiffened steel plates (BSSPs) were placed in the joint region to form a new type of strengthened extended end-plate connection (SEEC). BSSPs are beneficial to improve the robustness of EECs against progressive collapse. Display omitted •A new type of strengthened extended end-plate connection (SEEC) is proposed.•The geometric motion characteristics of the bending stiffened steel plates (BSSPs) are described through theoretical analyses.•The process of resistance development in the SEEC comprises three stages: elastic, transition, and improvement.•SEEC can obtain a more significant improvement stage.•SEEC design process is given. In this paper, a new type of the strengthened strategy for the limited anti-collapse capacity of extended end-plate connections (EECs) is proposed. Bending stiffened steel plates (BSSPs) were placed in the joint region to form a new type of strengthened extended end-plate connection (SEEC). First, the geometric motion characteristics of the BSSPs on the tensile and compression sides of the joint are described through theoretical analyses, and the improvement mechanism of the anti-collapse performance of the SEEC is given. Subsequently, using the verified numerical model, nine groups of parameters affecting the ultimate rotation of the EEC were analyzed, and the calculation formula for the ultimate rotation of the EEC was given via nonlinear fitting based on its numerical results. The numerical analysis example shows that the process of resistance development in the SEEC comprises three stages: elastic, transition, and improvement. Among them, the BSSP works well with bolts and end plate, which makes the SEEC obtain a more significant improvement stage and proves that the BSSP design process is reasonable. Finally, the main parameters a1, b1, and the thickness of the SEEC, were analyzed and suggested using parametric analysis.