In this decade, several 4-span suspension bridges were constructed or being under construction as a choice of economical bridge type. Although, there is a problem that the deflection of the center tower and the stiffening girder becomes large under eccentric live loads. In this study, we conducted the trial design of 4-span suspension bridge with the center span length of 1000m, considering buckling check and stiffeners of towers. In addition, the design method based on the rational live load is applied. Then, the dominant load condition when determining the cross section of towers and the influence of buckling strength curves to tower design is discussed.
