Parametric Design of Scroll-shaped Pylon of Single Tower Cable-stayed Bridge

Using single-tower cable-stayed bridge as example, this article introduces the design and construction process of a cable-stayed bridge with a scroll-shaped tower, as well as the optimization process and detailed design process of the steel structure of the scroll-shaped part of the bridge pylon.Based on Rhino+Grasshopper software, parametric design was used to design the bridge tower's shape while ensuring the balance of tower strength, stiffness, and stability. The shape was designed as close to the original landscape plan as possible, and the following work was conducted: (1) Determination of the the pylon’s overall proportion, based on Golden Section principle, including the size of three main elliptical sections at the top, bottom, and waist, as well as the determination of the circular arc transition in the middle, the pylon shape match perfectly with the landscape plan; (2) The shape of the tower crown is found by the golden section ratio plus helix, and the structure of the tower crown adopts double shell. The structural calculation shows that the strength and stiffness of the double shell meet the requirements when the inner and outer layers are 10~12mm thick and the ring stiffening +1 circle and 20 vertical stiffening every 1.5m; (3) To find the shape of the pylon’s turned edge, according to the shape of the rotary rising edge from the original model, by constructing the parameter of the control point, and generating the integral shape, adjusting the parameter until the shape meets the original pylon model. (4) After the concrete scroll edge and the main tower bottom are cast together, the stress distribution of the tower foundation scroll edge under permanent load, live load, and overall temperature rise and fall conditions is analyzed, and the proportion of its force sharing with the main tower is calculated, calculation shows that the main force of the flange is compression, which is consistent with the main tower structure. Only under the most unfavorable conditions with the maximum bending moment, there is a small tensile stress in the flange.