## 1 Introduction
Some work has focused on modifying the blind bolt to reduce the likelihood of local bucking of the steel tube by setting a device anchorage for the blind bolt to improve the anchorage characteristics of the fastener. First, [PERSON] and [PERSON] [7] proposed to weld a piece of straight or hooked reinforcing bar to the end of the bolt shank for the blind bolt. Then, they focused on modifying an Ajax Oneside to investigate the tensile behavior of blind bolted T-stub connections to circular CFST columns with a straight or hooked reinforcing bar welded to the blind bolts [8,9]. The test results showed that the anchorage provided by the extensions can limit the localized bulging of the tube face and dramatically improve the strength and stiffness of the connections in tension. However, weld fractures easily occurred between the reinforcing bars and the bolt ends would easily form if precautions were not taken, and short extensions would result in anchorage failure. Furthermore, the final direction of the hooked reinforcing bars after tightening could not be guaranteed to be consistent. [PERSON] et al. [10, 11, 12, 13] investigated the behavior of blind bolted end-plate (flush and extended) connections to square and circular CFST columns; in this work, 50-mm-long straight extensions were used for the blind bolts, and similar conclusions were drawn. Then, [PERSON] and [PERSON] [14] proposed the Extended Hollo-Bolt (EHB), which extended the bolt shank of the Hollo-Bolt and attached an anchor nut at the end. [PERSON] et al. [15] conducted a comprehensive experiment on a novel anchored blind bolt in tension, indicating that the anchored blind bolt can finally achieve the ultimate strength of its internal bolt to enhance the tensile strength and stiffness of the blind bolt. This research was continued by [PERSON] et al. [16; 17], who carried out a series of monotonic and cyclic loading tests on blind bolted end-plate connections to CFST columns using EHBs, which exhibited a high ductility and energy dissipation capacity suitable for use in seismic design. These conclusions were further confirmed by the research reported by [PERSON] et al. [18], who studied the tensile performance of the modified Ajax Oneside with an anchor nut at the end. For the current literature review, little attention has been paid to the anchored blind-bolted joints between CFST columns and steel beams. For those joints, cyclic loading tests are limited, and the test parameters are incomplete. It is also short of theoretical research, especially for the connection stiffness, and no specific design method was available for those connections. Moreover, in order to relieve the steel tube deformation, previous studies prone to increase the tube wall thickness along the length of the column, and consistently increased the thickness of locally strengthened steel tube. Therefore, the proposed moment-resisting bolted connection to CFST columns adopts the modified blind bolts and a locally strengthened steel tube in the panel zone. It is expected that the capability of each component can be fully utilized and a greater economic benefit can be achieved. Two simple improvement method mentioned above combined to modify the bolted connections between CFST columns and steel beams, which can provide a more effective, economical, and construction-friendly solution to the flexibility of the tube face in the tensile zone. The new proposed connection can allow for the application of those commonly used bolted connections in moment-resisting frame. The following parametric experimental analysis and theoretical analysis of the connection stiffness will provide a comprehensive investigation to help the development of this system. A total of six proposed anchored blind bolted flush end-plate joints were tested under cyclic loading to investigate their cyclic characteristics. Finite element (FE) analysis models using software ABAQUS were developed for the connections, and the results obtained from the FE models were validated against the test results.