## 6 Conclusions  
This paper presents a novel analytical model to analyze the mechanical performance of the cable-stayed suspension hybrid bridge, which is developed based on the modified suspension-elastic foundation beam theory with the consideration of the overlapped section between the suspension and stayed cables. The governing equations of the hybrid bridge system are derived based on the elastic beam foundation theory and the deflection theory, and the general solutions are also given. The influence lines of the main beam under the concentrated load are solved using the Transfer Matrix Method, while for the hybrid bridge system, the influence lines are solved by establishing the compatibility equation of the main cable with consideration of the longitudinal displacement of the main tower and no variation of unstressed length of the main cable. A case study is then presented to verify the proposed model using the finite element method. Meanwhile, the characteristics of the influence lines of the hybrid bridge system are investigated using the proposed model. The general conclusions are as follows. 1. The proposed model can accurately estimate the global deflection and internal forces of the hybrid bridge with the deviation within 5%. The derivation and solution of the proposed model can be easily complied in any programming platform with simple input parameters. Hence it can provide the theoretical basis for the verification of any complex finite element model with complex input data. In addition, the proposed model can overcome the difficulties in the finite element method during the bridge optimization, and hence, it can be used in the preliminary design stage. 2. For the complex hybrid system, the vertical deflection influence line of the beam at any location is approximately symmetrical about the concerned location, with the peak values occurring at the concerned location. In addition, a negative deflection zone for the main beam exists at a distance from the concentrated vertical load, which is mainly caused by the deflection of the main cables, leading to campering of the beam. 3. The influence lines for the moment and vertical deflection of the beam are approximately symmetrical about the concerned locations, while those for beam rotation and shear are approximately anti-symmetric about the concerned locations. In addition, the maximum values of the influence lines for the vertical deflection and beam rotation at the pure suspension section are larger than those at the hybrid and cable-stayed sections. It is clear that the proposed analytical model can accurately compute the structural deformation and internal forces of the long-span hybrid cable-stayed suspension bridge. However, due to some simplified assumptions made in the analytical model, such as the use of linear deflection theory and neglection of \(H_{p}v^{\prime\prime}\) in Equation (5), the results will, to some extent, deviate from the actual ones. In addition, due to the space limit, the methods to compute some critical parameters for the analytical model have not been given. These will be included in a companion paper to introduce the methods to compute the critical parameters, such as the longitudinal constraint stiffness of the main cable at the tower top, the vertical elastic support stiffness of the stayed cables to the main beam, and so on, and to perform a comprehensive parametric study on the structural performance of the bridge, including the span ratio of the cable-stayed part and sag ratio of the suspension part, and so on. **Author Contributions:** Conceptualization, S.Q. ; Methodology, D.H., S.Q. and S.W. ; Formal analysis, D.H.; Investigation, D.H., H.X. and S.W. ; Writing--original draft, D.H.; Writing--review & editing, S.Q., H.X. and S.W. ; Visualization, D.H. and H.X. ; Supervision, S.Q. and H.X. ; Project administration, S.Q. ; Funding acquisition, S.Q. All authors have read and agreed to the published version of the manuscript.