Study On Cable-Struts Arrangement Of Ellipse-Like Suspendome

In this paper, taking the ellipse-like suspendome of Suqian Yunhe Gymnasium as background, based on structure optimization result done before and deep research on the boundary curve fitting and meshing types, systematical study is done on different cable-struts arrangement of the ellipse-like suspendome structure.The main conclusions of this paper are as follows:1. A method of parallel ribbed mesh generation based on four-arcs method is applied so that grids of upper cylindrical shell are efficient and lower cable-struts system is regularly assigned. Different architectural appearances and layout of column system can be applied with the adjustment of parameters,which makes it feasible both for design and construction.2. When the length of long axis and short axis are specified, the arc length ratio is a key parameter related to shape of dome and arrangement of columns. A series of similar shape ellipse-like suspendomes are obtained by adjusting the arc length ratio. The characteristics of inner forces and displacement distribution are as follows:the bar with largest compressive stress is on the outermost arc of the long axis while the bar with largest tensile stress is on the outermost arc of the short axis. Signs of compressive stress and tensile stress change near the segmentation points. Vertical displacement is upward slightly at long axis and downward at short axis.3. Unlike round suspendome, ellipse-like suspendome based on four-arcs method is not a central symmetric structure. Under prestress load and vertical load, horizontal displacements following the radius direction of supports vary regularly.The inward displacement achieves maximum along major semi-axis while the outward displacement achieves maximum along short semi-axis. Horizontal stress transferred to lower supporting structure is much bigger than round suspendome. Cable-struts arrangement should be adjusted to reduce differences of forces and displacements in all directions so that the mechanics performance of ellipse-like suspendome based on four-arcs method can be improved.4. Three arrangement of cable-struts arrangement with different number of cable,arrangement with different angle of strut and arrangement with shape of step are applied to improve differences of displacements of ellipse-like suspendome based on four-arcs method in all directions but the effect is not obvious. Cable-struts arrangement with shape of a saddle in this paper is adopted, differences of displacements of ellipse-like suspendome based on four-arcs method in all directions can be practically resolved and radial displacements of supports under prestress load and vertical load will be nearly zero.5. The basic principles of cable-struts system with shape of a saddle are obtained by theoretical derivation and calculating example. Radial displacement of supports varies regularly following the change of struts'height. It varies directly as the height of struts at major semi-axis while varies inversely at short semi-axis.6. Based on parallel ribbed cable-struts system, the cable-struts system with shape of a saddle is obtained by adjusting the height of struts to form a saddle shape. The principles of adjustment are:based on method of self-balance loop by loop, adjust from the inside out. When adjusting in each loop, displacement distributions in cables are obtained when radial displacements of the segmentation points are zero, then maintain heights of struts at the segmentation points and adjust heights of struts at other points based on proportional relation of radial support displacement. The height of strut is reduced along the long axis from segmentation points and reaches minimum at the vertex of long axis. The height of struts increases along the short axis from segmentation points and reaches maximum at the vertex of short axis.7. Mechanics performances of ellipse-like Kewitte suspendome,ribbed suspendome and parallel ribbed suspendome are compared. Internal forces in cables and latticed shell of ellipse-like Kewitte suspendome and ribbed suspendome are smaller, but the difference of internal forces in circumferential cables are large so that cable clamps have to bear large anti-slide,which is difficult to solve in practical application.8. In ellipse-like parallel ribbed suspendome adopting the cable-struts system with shape of a saddle, distribution of internal forces in cables is uniform and vertical displacement is small so that the supporting structure is easy to design. Furthermore, elastic buckling and elastoplastic ultimate bearing capacity are satisfying. Although internal forces in cables and latticed shell are a little bit large and natural vibration period is long, ellipse-like parallel ribbed suspendome adopting the cable-struts system with shape of a saddle has obvious advantages according to comprehensively judgments so that it should have priority of application in similar projects.