| The reticulated mega-structure is a structural form based on the improvement of the traditional double-layer reticulated shell structure,which is made available for larger spans.The transmission path of forces of this kind of structure is clear and its configuration is more reasonable,for which reason it has been well applied in both industrial buildings and public buildings.In this thesis,a reticulated mega-structure with a transverse section of a three-center cylindrical surface is constructed,the model of which is then established in ANSYS/LS-DYNA for elastoplastic seismic analysis considering the effect of traveling wave.The displacements of the key nodes in the structure and the axial force of the members are meticulously analyzed,and the failure modes of this kind of structure under the excitation of strong earthquakes is studied in detail.The main contents are as follows:(1)To analyze the geometric relationship of the transverse section of the three-center cylindrical reticulated mega-structure,to determine several parameters as the main factors for structural design,and to compose a calculative formula that is applicable to the threecenter cylindrical reticulated mega-structure,for the facilitation of parametric modeling.(2)With a total of three seismic waves adopted to uniformly excite the structure,the displacements of critical nodes and the axial force responses of key rods in the structure are mainly investigated,through which the key nodes and key members used in this research are determined.Combined with the previously determined key nodes and members,the analysis of travelling wave excitation on the structure,in both arching direction and longitudinal directions under the action of different apparent wave velocity,is conducted,so as to study the regularity of dynamic response of the structure.Through this research,it has been found that it is necessary to consider the influence of traveling wave effect in seismic analysis of this type of structure.The structure response under the traveling wave excitation in arching direction is greater than that under the uniform excitation of seismic wave,while the general response of the structure under the travelling wave excitation in longitudinal direction is relatively low but the members near the supports is seriously damaged.(3)According to the geometric configuration of the transverse section of the structure,various parameters such as the vector-to-span ratio,the inclination angle at which the end of structure meets the ground,and the size of the sub-structure cross-section,etc.are changed during the establishment of different models for doing analysis.Then the influences of these parameters on the mechanical performance of the structure are studied.It has been found in this research that a appropriate increase in the vector-to-span ratio and the inclination angle could reduces the internal forces of the structure effectively.Due to the special configuration of the reticulated mega-structure,the members of substructure could be selected to be smaller than the minimum cross-section specified in the relevant design code.(4)To summarize the failure modes of the structure through the analysis of the sequence by which the members of the structure become failed under the action of strong earthquakes,and to establish a variety of structural models to analyze and statistically count the vertical displacements of the key nodes of these structure.The analysis results indicate that the displacement of the key nodes of the structure can be used as the criterion for determining whether the structure has collapsed or not in structure design. |
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