## 7 Conclusions  
The observations and conclusions of the experimental and analytical study reported in this paper can be summarized as follows:  
1. The observed results demonstrated that the application of the modified anchored blind bolts (Hollo-Bolt) and a locally strengthened steel tube column in the panel zone can effectively avoid the premature anchorage failure and CFST column damage for the bolted connections to square CFST columns in the moment-resisting frames. No obvious damage was observed for the embedded extensions of the blind bolts and C-shaped channels, providing a stable and sustained effect on the joint performance during cyclic loading. The proposed connection demonstrated its ability to reach the ultimate strength of the blind bolts and significantly improved the performance of the connections in terms of the flexural resistance, stiffness and stiffness degradation. 2. Two representative failure modes were presented in the test for the anchored blind bolted connections to square CFST columns. The tube wall thickness and blind bolt anchorage method mainly determined the failure mode, and the end-plate thickness and steel beam section had an influence on joint deformation. Connections that failed in mode II exhibited higher flexural resistances and stiffnesses, while better rotation ability, ductility and energy dissipation capability were observed for connections that failed in mode I. For connections that failed in mode I, the good deformation capacity is mainly achieved by the deformation of the steel tube walls and the crushing of concrete in the columns. For connections that failed in mode II, using thin end-plates and a weak steel beam could produce a good deformation capacity, avoiding premature brittle fracture of the connections while maintaining a high flexural resistance. 3. Due to the change of failure mode, the use of locally strengthened steel tube can not only enhance the initial stiffness and strength of a connection but also reduce the counterpart rotation capacity and ductility. The use of thin end-plate and weak beam can effectively enhance the hysteretic behavior, ductility, and energy dissipation capacity of joints. The change in anchorage method has a great influence on the flexural capacity but has little effect on the stiffness. 4. The rotation capacity and the ductility of these anchored blind bolted joints can satisfy the requirements for structural earthquake-resistant design in most seismic areas. In accordance with EC3 Part 1-8, most blind bolted flush end-plate connections to CFST columns were classified as semi-rigid and partial strength, except specimen ST-6 with a weak beam, which shows semi-rigid and full-strength behavior. 5. An FE model of these anchored blind bolted joints was also developed in this study using ABAQUS/Standard module. It is shown that the model could simulate the connection behavior  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Specimen** & **Tube Thickness** & **Endplate** & **Vertical Bolt** & **Bolt Diameter** & \multirow{2}{*}{\(K_{\text{theory}}\)} & \multirow{2}{*}{\(K_{\text{FE}}\)} & **Ratio** \\
**(mm)** & **Thickness (mm)** & **Distance (mm)** & **(mm)** & & & \(K_{\text{theory}}/K_{\text{FE}}\) \\ \hline M-1 & 5 & 12 & 100 & 16 & 9.90 & 11.96 & 0.83 \\ M-2 & 8 & 12 & 100 & 16 & 12.14 & 13.75 & 0.88 \\ M-3 & 12 & 12 & 1  
successfully, particularly predicting the stiffness of the anchored blind bolted joints obtained in the early stage with sufficient precision. According to the mechanical behavior of the connection components, the component model of such a joint is proposed, and the initial stiffness expression is established. The expression was verified by the experimental results and the results obtained from numerous parametric FE models, demonstrating the reliability of the initial stiffness expression. The current work can provide a good understanding of the performance of the proposed connection, which is an important reference in actual engineering.