Research On Design And Construction Of Super-span Prestressed Cable-stayed Grid Structure

As a standard of civil engineering, A deeply development of spatial structure has been achieved in recent years. No matter in terms of structure type or in terms of spatial span, breakthrough and innovation has been realized. However, the limit of 300m span still need to be solved with the increment of human requirement. Therefore, it is necessary to research spatial structure in huge space and huge span. As a special type of spatial structure, the prestressed cable-stayed grid structure, composed of grid structure and cable-stayed structure, belongs to suspension system which cable-stayed bridge with more than 1000m span is also a part of. Referring to experience and technic of cable-stayed bridge, the prestressed cable-stayed grid structure could break through the limitation of 300m span in order to satisfy the demand of human on huge space and huge span structure.The main task of this paper is to do feasibility study of large span prestressed cable-stayed grid structure and construction of this structure.This paper summarized relevant information of prestressed cable-stayed grid structure, including types、characteristics、engineering application、 development status. A designed prestressed cable-stayed structure was analyzed according to current analysis theory, and the key is to use "unknown load coefficient" method to determine the cable force values. Otherwise, perstressed cable-stayed grid structure construction method, dividing into construction of grid structure and cable-stayed structure were introduced. Grid structure construction method covered with bulk method, block sliding method, the integrally installation method for the traditional method of grid structure construction methods; Pantodome system method, hydraulic integral lifting method, hydraulic integrally jack-up method represented the new grid structure construction methods; This paper also made a brief introduction on cable-stayed structure construction, including the truss column construction, cable installation and cable tension.Based on finite element analysis software Midas, the designed 500m span prestressed cable-stayed structure was modeled and analyzed. According to 《Load code for the design of building structure 》 and 《Code for design of steel structure》 and considering structure dead load、live load、wind load、 temperature load、tension load and response spectrum effect, relevant analysis, including stiffness analysis、stress analysis、bearing force analysis and modal analysis, was carried out on the structure. The result show the largest cross section was P1000×100, and costs of steel were 73,000 tons, a economic steel cost compared with other structure in same level. The maximum deflection was 920mm, meeting the requirement of relevant code. The result verified the rationality、the economy and the feasibility. The designed prestressed cable-stayed grid structure used the improved Pantodome method and hydraulic integrally jack-up method for grid structure and used hoisting method with cable wind rope for truss column. In the installation of cable, the paper choose the installation method of one end of the traction or the installation method of pulley loop. In the tension of cable, the degradation of compensation method and the method of tensioning several cables in batch. The analysis result,345mm of the max deformation and 360Mpa of stress, verified the safety、rationality and feasibility.