Structure Analysis And Research Of Special-Shape Arch Bridge

Special-shape arch bridge is a new type of bridge structure, which is a diversified form of conventional arch bridge. In order to meet aesthetic requirements, a special-shape arch bridge is usually unique in structure shape. And therefore, the structure of a special-shape arch bridge is much more complex than that of a conventional one, especially in terms of stress analysis. Of the study on a special-shape arch bridge, it is necessary to focus on the optimization of its arch axis and analysis on the stress and nature vibration feature of the structure.This paper first studies the method of arch axis optimizing for a special-shape arch bridge. A case study on a through arch bridge over the Hangyong Canal is shown with finite element code. In the numerical models, the stress relationship between the nodes and elements of the proposed arch axis under a prescribed load condition are analyzed by iterative calculation, and the coordinate values of the points along the pressure line of the arch rib are accordingly approximated. A rational arch axis then can be designed through the method of least square polynomial fit with the coordinate values.Of a sunflower-shape arch bridge, the large horizontal thrust at spring of its spandrel arch makes it different from conventional arch bridges. A method of optimizing the span of spandrel arch, rise-span ratio and axis coefficient is given, through analysis on the influence line of spring and mid-span of the main arch. A case study on the Xiaohe Bridge, with 3D Dr.Bridge code, is illustrated to show the difference between sunflower-shaped arch and bare arch in terms of influence line and structure stress sensitivity.This paper also studied the dynamic natures of special-shape arch bridge. A case study on a special-shape reinforced concrete deck arch bridge, which is located in the Economic Development Area, shows the calculation procedure of the analytical solution of natural frequency of a parabolic arch bridge with cable. The analytical solution is checked with numerical method with 2D MIDAS code. The natural frequency and vibration mode characteristics of the bridge are calculated, and the influence of the column (suspender) slope and section shape of the arch rib on the vibration of the bridge is analyzed, with 3D finite element model. The results of this study should be beneficial to similar cases.