## 6 Conclusions  
In this study, the dynamic performance assessment of a reference structure with accuracy multi-axial dynamic sensitivity including human-structure interaction effects was performed using the RTHS technique for the three gait velocities of the pedestrian: 1.20, 1.50, and 1.80 m\(\cdot\)s\({}^{-1}\). The main conclusions are as follows. 1. The assessment of human-induced gait loads on the reference footbridge revealed significant interactions between pedestrian activities and structural responses. Both lateral and vertical loads exhibited dynamic coupling, with frequency content closely aligned to the footbridge's natural frequencies, particularly in the range of 1.0 Hz and 1.8 Hz. This dynamic synchronization, particularly during higher gait velocities, amplified structural vibrations, especially in the middle span, leading to increased loading by up to 300.0% in lateral directions. Vertical loads showed similar variation, with substantial amplification and attenuation depending on the gait velocity and footbridge position. These findings highlight the critical role of human-structure interaction (HSI) in dynamically sensitive structures, underscoring the importance of accounting for these interactions in the design and evaluation processes to ensure serviceability and safety under regular pedestrian use. 2. The performance analysis of the reference footbridge under human-structure interaction (HSI) effects demonstrated significant dynamic responses in both the lateral and vertical directions, particularly at higher pedestrian velocities. Lateral accelerations and displacements exhibited a fundamental frequency around 1.0 Hz, whereas vertical responses peaked near 2.0 Hz. The coupling of pedestrian-induced loads with footbridge dynamic properties led to increased vibration amplitudes, especially in the middle span. Lateral accelerations showed a dispersion of approximately 15.0%, whereas vertical accelerations exhibited higher variability, with dispersions reaching up to 20.0%. Moreover, the percentage difference between lateral and vertical displacements was less than 10.0% for all evaluated gait velocities. These findings underscore the critical importance of integrating HSI considerations into footbridge design because human activity can induce substantial variations in structural performance, potentially affecting serviceability and user comfort. 3. The experimental assessment was performed using the RTHS technique, taking an analytical continuous model (through a fourth-order partial differential equation) of the reference structure with accurate multi-axial dynamic sensitivity as a numerical substructure and the gait of the test subjects as an experimental substructure. All cases had high-level tracking for the horizontal and vertical transfer systems, which developed a generalized amplitude A\({}_{0}\) around 1.0 and global errors lower than 2.95%. Furthermore, HSI-MTF had delays of less than 2.10 ms in all directions evaluated with an NRMS of less than 2.95%, employing a robust H\({}_{\infty}\) type controller in the lateral axis and a PID setup with a phase anticipator in the vertical axis. The above results indicate that the RTHS exhibits high fidelity and accuracy. **Author Contributions:** Conceptualization, J.M. and B.C. ; methodology, B.C., J.M. and P.T. ; software, B.C. ; validation, B.C. ; formal analysis, B.C. ; investigation, B.C. and P.T. ; writing--original draft, B.C. ; writing--review and editing, B.C., J.M. and P.T. ; supervision, J.M. and P.T. ; project administration, P.T. All authors have read and agreed to the published version of the manuscript. **Funding:** This work is part of the research project: Real-time hybrid simulations: a reliable, fast, and economical alternative for the evaluation of resilient structures; under the program: Emerging technologies for the mitigation of seismic risk in civil infrastructure, CT 463-2020--program code: 110685270483.