The Static And Dynamic Analysis Of Triple-layer Space Trusses

Triple-Layer space trusses are organic combination of double-layer space trusses. Its appear is an important deploitation for space structure field. For the advantages of larger stiffness, reasonable distribution of internal force, favorable technical economic characteristics and manufacture convenient etc, triple-layer space trusses are used increasing widely in large span space structures. As for much more types of triple- layer space trusses, it is necessary to particularity analysis their static and dynamic behaviors. In this paper, static and dynamic studies on some types of triple-layer space trusses with ream member model were processed. Based on the space truss displacement method, the modified full stress method, the subspace iteration method and the mode- superposition response spectrum method, an analysis program of space trusses was compiled with Fortran 90 computer language. With this program, two novel types of triple-layer space trusses -- leaning-laid pyramid triple-layer space trusses and leaning- laid pyramid triple-layer space trusses with openings were studied. Compared with this two novel types, three customarily used types -- diagonal square pyramid triple-layer space trusses, orthogonal square pyramid triple-layer space trusses and orthogonal square pyramid triple-layer space trusses with openings were studied too. The result indicated that compared with orthogonal square pyramid triple-layer space trusses and orthogonal square pyramid triple-layer space trusses with openings, leaning-laid pyramid triple-layer space trusses, leaning-laid pyramid triple-layer space trusses with openings and diagonal square pyramid triple-layer space trusses have advantages of more reasonable distribution of internal force, reduced the maximum of internal force, much more favorable technical economic characteristics arid better capability of oppose vibrate etc. They are three better types of triple-layer space trusses that compete successfully with more conventional types. Furthermore, technical economic characteristics of triple-layer space trusses and double- layer space trusses were compared. The results indicated when used in large span and middle span, triple-layer space trusses have more reasonable distribution of internal force, good economic effects, reduced the maximum of internal force and more favorable technical characteristics. Based on the analysis, some suggestions for engineering design of triple-layer space trusses are given, and the problems that need to be further studied are presented.