A unique 3-tower, 4-span suspension bridge is under construction in Wenzhou, China. The suspension spans are 755’ (230m) x 2,625’ (800m) x 2,625’ (800m) x 1,175’ (230m) in length, and the towers are 477’ (145m) in height. The bridge carries two levels and a total of twelve lanes of traffic, and its design service life is 100 years.

 

The unique bridge configuration is a result of a clearance restriction imposed by a nearby airport and the need for two wide, 1555’ (474m) and 899’ (274m), navigation channels. An "A" shaped concrete tower was selected for the center tower to provide adequate rigidity. The superstructure is continuous for 6,906’ (2,105m) and is made of steel trusses, which is 119’ (36.2m) wide and 41’ (12.5m) tall between centroids of truss chords.

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CHI performed an independent checking of the design of the steel superstructure, focusing on the strength and fatigue performance of the superstructure under vehicular traffic. CHI adopted a synergic approach that combines 3D CAD modeling, finite-element analysis, customized post-processor to achieve the best accuracy and efficiency. Engineers in CHI created a refined 3D CAD model of the superstructure with the accurate geometry of all steel elements including perforations and orthotropic deck details, leading to rapid generation of a high-fidelity finite-element model. Stress and fatigue analysis was then conducted in conjunction with programming during pre- and post-processing allowing automation in parametric study and rapid identification of design deficiencies. Design and optimization modifications were developed, analyzed, and proposed.