Analysis On Kinmetic Stability Of Loaded Linkage Mechanisms And Length-error Effect Of Cable-strut Structures

Large-span spatial structures have been applied widely in many fields, with new forms and systems frequently developed by civil engineers. According to some key construction technology of large-span spatial structures, this thesis mainly studies the kinematic shape and stability of loaded linkage mechanisms which come from the deployable construction of cylindrical latticed shells, and initial pre-stress loss resulting from length errors of cable-strut tensile structures during the construction as also.Firstly, based on the energy criterion, this thesis put forward an uniform method to determined the stability of cable-strut structures by eigenvalue analysis of tangent stiffness matrix, which is good for analyzing the stability of every equilibrium shape. According to comparison with the traditional product-force method, it is pointed out that the product-force method is not a sufficient condition for the stability of cable-strut structures, but the method mentioned in the thesis is necessary and sufficient condition. It is also indicated that the eigenvector corresponding to the zero eigenvalue of the elastic stiffness matrix is mechanism displacement model by eigenvalue analysis of stiffness matrix. -With the background of the deployable construction of cylindrical latticed shells, this thesis discusses the kinematic shape and stability of loaded linkage mechanisms. According to analysis of symmetric lifting and lift-up construction as well as asymmetric lifting construction on loaded linkage mechanisms, it is summarized the kinematic characteristics of the system during the construction in the thesis. For resolving the problem of the instability of linkage during the construction, the measures improving the kinematic stability is studied. Based on the components of tangent stiffness matrix, the thesis analyses the effect factors of the kinematic stability of loaded linkage mechanisms: the geometry and internal force distribution of the system.For resolving the problem of the initial pre-stress loss of cable-strut tensile structures during the construction, the sensitivity analysis method on the initial pre-stress is indicated on the basis of length errors. According to establishing the random model of the normal distribution length errors, and taking the mast-cable hybrid system for example, the shape and initial pre-stress analyses are carried out respectively to identify the effect of length errors to the structure. It is also investigated the effect of the construction schemes and relaxing the length-error limited value on the initial pre-stress.