3D Parametric Design And Safety Evaluation Of Crescent-Rib Reinforced Branch Pipe

When central or grouping water supply is employed in diversion system for hydropower station, branch pipe need to be settled up. It is a key building of pipeline, considered as its "throat". There are many kinds of structural types for branch pipe including crescent-rib reinforced branch pipe (CRRBP). For having advantage of well bearing capacity and easily fabrication and installation, CRRBP has been widely applied in large and middle hydropower station, especially in pumped storage power station. However, CRRBP is a type of combination structure with steel shells and reinforced rib, which causes complex stress state in the structure. The present design method for CRRBP is given based on analytical analysis with lots of idealizations, and has many complex steps in practice. For the reasons mentioned above, the structural analysis step in the design method cannot be accurately used in safety evaluation of this type of branch pipe. Considering possibility of significant loss of life and property in event of CRRBP accident, some research work aiming at providing3D parametric design and safety evaluation method for CRRBP has been done:(1) A3D parametric method is proposed for structural design of CRRBP. By combining programming languages, design and analysis software, a3D parametric design method is presented for CRRBP. The method can significantly improve the efficiency of design of the structure.(2) Based on stress index and its analysis method, improved safety evaluation is proposed. Suggestion on model scope and boundary condition is given, and main influence factors on structural response and their engineering law are provided. The conceptions of hot spot stress and bearing ratio are adopted, and some effective safety evaluation method is presented.(3) Based on internal force index and its analysis method, the safety evaluation is proposed. The nodal force based internal forces analysis is employed, and a new safety evaluation method of crescent rib is presented. By introducing generalized yield criterion of shell, a new safety evaluation method of CRRBP is presented.