Theoretical And Experimental Research On A Novel Prefabricated Spherical Lattice Shell Composed Of Six-bar Tetrahedral Units

The extensive developing mode of China’s traditional building industry is in strong tensions with the resources and environment, since the economic and social development has made demanding requirements for reducing the waste and pollution caused by the manufacture and construction process. To promote the building industrialization, in which the research and development of industrialized structural systems is the primary task, has been proved to be an effective way to tackle the problem according to the worldwide experience. This research proposes a novel spherical lattice shell that serves China’s building industrialization and seeks to facilitate its application in practical engineering. The structural system is composed of six-bar tetrahedral units whose planar projections are quadrilateral, and is suitable for industrialized manufacture and prefabricated construction due to its simple and regular form. Study on this lattice shell is carried out theoretically and experimentally, and the contents can be stated as follows.Chapter1summarizes the state of the art of lattice shell structural systems and their analysis methods, as well as the development of prefabricated space grid structures. Then the purpose and significance of the research in this dissertation is clarified and the main work is introduced.Chapter2discusses the similarities and differences between the six-bar tetrahedral units proposed in this thesis and the regular pyramid units. The key geometric parameters determining the configuration of the spherical lattice shell composed of six-bar tetrahedral units are extracted, and the basic structures with or without inner-ring members are defined depending on whether the hole on the top of the lattice shell is enclosed. This chapter also probes into the possibilities of composing other structural systems for the six-bar tetrahedral unit.Chapter3carries out kinematic analyses of the spherical lattice shell based on Maxwell’s rule and equilibrium matrix theory, with the conclusions proved strictly. Then the ways of forming different strengthening structures and nodal joint rigidity arrangement patterns and their theoretical foundations are given.Chapter4focuses on the static behavior of the spherical lattice shell. The main aim is to calculate the distributions of internal forces and nodal joint displacements. Comparisons among the results of basic structure and two strengthening structures with four different joint rigidity arrangement patterns are made. A parametric study is also conducted.Chapter5investigated the stability performance of the spherical lattice shell. A modelling and calculating method accounting for member instability in the stability analysis of the entire structure is proposed in the first place. The eigenvalue buckling and nonlinear analyses are carried out subsequently, adopting the proposed method. A parametric study on the stability performance of the lattice shell is implemented as well.Chapter6deals with the practical issues of the spherical lattice shell. Construction details for a particular type of nodal joint that can generate good structural performance are developed. A construction scheme, in which the spherical lattice shell can be erected by protrusion without scaffold, together with some essential instruments needed during the erection process, is presented, followed by a corresponding construction analysis.Chapter7conducts an experimental study on the spherical lattice shell based upon the previous theoretical work. A10m-span model of the lattice shell is built to verify the feasibility of prefabricated construction. Then the installation accuracy is measured and the finite element model is reestablished using the measured nodal joint coordinates, based on which the influence of the installation error on the static behavior can be investigated from a theoretical viewpoint. Finally a static test on the structural model is executed and comparisons between the measured and theoretical results are made, with error sources and the way they influence the static behavior estimated.Chapter8draws the conclusions and points out some directions for further studies.