Analysis And Monitoring Of Large-Span Space Structure During Construction

It is well-known that the modern large span space structure has evolved into the most popular structure type all over the world because of its special advantages and challenge. Turn into 21 century, in our country a great progress has made in the construction of large span space structure on the side of number, span, type, style etc. With infrastructure construction rapidly development in our country, the construction capacity of large span space structure is called for higher level.Function of construction monitoring and analysis is a connection between that of the design and construction. It is not only one of the most important works but also one of the most difficulty works during construction of large span space structure. Large span space structure monitoring and analysis is a crossing subject including geodesy and disaster prevention and mitigation engineering. To raise the level of the technologies of construction monitoring and analysis have great significance for better quality and less expense in large span space structure.The thesis deals with a theory and some research on key technologies of construction monitoring and analysis of large span space structure. The theoretical innovations and main achievement of this dissertation can be summarized as follows:1. Research on confirmation of deformation monitoring precision indexesConfirmation of deformation monitoring precision indexes is one of the keys of deformation monitoring. Firstly, this dissertation systemic introduces main indexes and precision demands presently. Secondly, three important definitions(permissible deformation value, critical deformation value, degree of safety) are extended only for large span space structure. Thirdly, on the basis of methods of confirming deformation monitoring precision indexes summarized, methods of confirming large span space structure deformation monitoring precision indexes are gained by comparison and analysis of correlative examples and new opinions are proposed. Finally, methods of confirming deformation monitoring precision indexes are more perfect.2. Study of large span space structure monitoring technology Large span space structure monitoring technology is one of the keys of the dissertation. Technologies and methods of exterior deformation monitoring, inner stress measurement and cable force measurement are systemic introduced and integrated for the first time in this dissertation for large span space structure construction monitoring. On the side of exterior deformation monitoring, this dissertation proposes and proves the utility monitoring scheme by using general ground monitoring technology and the method of simplification differentiation polar coordinate survey for large span space structure deformation monitoring. On the side of stress measurement, this dissertation proposes an new method of stress measurement suit for mass concrete triangular frame and discusses shrinkage and creep of concrete how to influence stress measurement, and sets up finally a process how to calculate concrete stress through data for piano wire sensors. Finally, on the side of cable forces measurement, this dissertation discusses principle and measurement technology of frequency method.3. Research on finite element methodApplication research on large span space structure FEM simulation analysis is one of important theory basis in this dissertation. Studies four types finite element such as truss element, beam element, shell/plate element and solid element for the Xinguang Bridge and the Guangzhou international conference exhibition center. Then introduces geometric and tension & compression characteristic that should belong to structure for those kinds finite element simulation analysis, displacements distribution and stiffness matrix of truss element and beam element, thin plate bending theory and element shape functions and formulation and integration scheme of 20-node hexahedron.4. Research on Monitoring and structural analysis of the Xinguang Bridge constructionAs a engineering application of the proposed theoretical and technological studies, This dissertation introduces construction procedure and important period of the Xinguang Bridge, systemic studies structural finite element model and simulation calculate, then on the basis of simulation calculate confirms arrangement of the cross-section and point for strain and temperature monitor of the Xinguang Bridge, studies and develops the network and remote monitoring system on the platform of the collection instrument module, realizes gathering and dealing with measured data real time, by comparison actual value with simulation calculate one, then more scientific evaluates true status and degree of safety of the Xinguang Bridge big part of arch during rising up. Systemic studies setting up of construction monitoring control network, control of arch rib linear indexes and improvement of survey precision, then gains linear inflect characteristic and regularity of the arch rib. Systemic studies environment temperature how to influence construction control, finds out linear regularity and function formula of the arch rib, selects optimal closure time, then fully meets requirements of closure precision and linear. By testing a lot of data on temperature and strain and adopting least squares collocation, this dissertation deduces the strain calculate formula that is amended by joining temperature factor, then improves accuracy of stresses testing data. In the Xinguang Bridge engineering practice, as a result, the closure errors of the Xinguang Bridge reach a high accuracy, as well as all the final girder elevation, cable forces and structural inner forces.5. Research on analysis and geometric deformation monitoring of the roof truss-string applied to Guangzhou international conference exhibition centerAs another engineering application of the proposed theoretical and technological studies, this dissertation proposes both the content and the scheme on monitoring of the new type large span truss-string structure which is the largest one in China presently, it is proved chord rigidity happens more attenuation after cold bending of steel tube of truss-string. The measured results are proved that this approach can fully meet high precision requirement demands. Deformation parameters and characteristics of the truss-string in the different construction periods are obtained. In the engineering practice, by comparison calculation value with actual one, a rational construction stretching scheme is found out, then it fully meets construction requirements, at the same time attenuation characteristic of structural system rigidity is found. And as a result, the construction control indexes of the Guangzhou international conference exhibition center roof reach a high accuracy, a lot of valuable actual data and conclusion for similar projects construction and design are obtained.