Study On The Form-finding And Static-load Anlysis Of Cable-membrane Structure

Cable-membrane structure, a new building system developed in 1970s, is an important part of spatial structure and used widely in large span structures. Domestic and overseas researches on cable-memebrane structure are mostly conducted from the theoretical aspect, but seldom from the applicational aspect. In the cable-membrane design, the decision of material, rise-span ratio, and pretension are usually made experientially. Consequently, a deep research of these variables' iniulence on the design of cable-membrane will be of great value.In this paper, the performence and characteristic of cable-material were summerized and the influence of cable-material on the design of cable-membrane was analyzed. The basic elements and content in cable-membrane design were introduced.Based on the analysis and comparision of these fllowing three methods in the membrane form finding, including the Dynamic Relaxation Method(DRM), the Force Density Method(FDM) and the small elastic modulus method (SEMM), a synthetical analyzing method by combining SEMM was proposed based on the finite element thesis. By using the ANSYS software, the feasibility of this method was demonstrated through several structure finding analysis on the typical surface, including catenoid and multilateral saddle surface. The influence of the tensile stiffness, the pretension and boundary-conditions on the cable-membrane form finding was studied based on the analysis on the inverted umbelliform membrane form rinding.The load types and load combination that should be considered in the cable-membrane design were analyzed and summerized, and the formula for the rain and snow load calculation was deduced. The influence of the variety of these basic varibales including tensile stiffness, pretension, rise-span ratio and environment temperature etc. on the load analysis of cable-membrane was studied by analyzing the static load of multilateral saddle surface with ANSYS. Accordding to the reliability as the evaluation standard, the initial design model of national stadium cable membrane was optimized, and the advantages and disadvantages between the pre-optimization and the post-optimization were analized, which would be a valuble referrence in the future design and construction.