A New Technique for Calculating the Effective Length Factor of the Tower in Cable-Stayed Bridge

Abstract

The stability issues of the tower column (hereinafter referred to as ‘tower’) in the cable-stayed bridge are studied in this paper. Two types of cable-stayed bridges are considered, namely inclined tower cable-stayed bridges without backstays and floating single-tower cable-stayed bridges. Based on the structure feature of the inclined tower cable-stayed bridge without backstays, a novel double-beam model with discrete springs is established to facilitate the linear elastic buckling analysis of the tower. To solve the model, the transfer matrix method is applied, and the stability characteristic equation of the system is derived by considering the boundary and continuity conditions. In this way, the effective length factors for the longitudinal stability of the tower are obtained. At the same time, the finite element method is utilized to verify the results obtained by the proposed model and method. Then, the parametric analysis is conducted to explore the effects of some structure parameters on the effective length factor of the tower. In addition, the influence on the effective length factor of the tower is investigated in detail when the steel cables are replaced with CFRP cables for an inclined tower cable-stayed bridge without backstays. Finally, the same processing method is extended to derive the effective length factor of the tower in the floating single-tower cable-stayed bridge. The comparison with the results of the finite element method confirms the feasibility of the present method again.