Studies on a large-span beam string pipeline crossing

Beam string pipeline crossing (BSP) is a new type of a self-supporting, large-span pipeline crossing structure. Based on the ANSYS program, the prestressing force of a 100 m span BSP was optimized using the first-order method, and the structural stability under three types of boundary conditions were analyzed and compared by nonlinear buckling analysis. In addition, some key geometric parameters, such as the rise-span ratio, rag-span ratio, struts arrangement, and cross section of the beam, string, and struts, were determined by parameter analysis. On this basis, a 1:15 model test was carried out to investigate the behaviors of BSP during the full-range, including the stretching phase, serviceability phase and ultimate load carrying phase. The test and analytical results of finite-element analysis showed that the stability and loading-bearing capacity of the BSP was reliable and the semispan water load case was the controlling load case in the design. Finally, calculation formulas for the deformation and internal force of BSP in the elastic stage and plastic ultimate load were proposed by the Ritz method.