Levy型劲性支撑穹顶静力性能试验研究

Experimental research on static behavior of Levy rigid bracing dome

为研究Levy型劲性支撑穹顶结构的静力性能,以跨度6 m的Levy型劲性支撑穹顶结构实际模型为研究对象,通过试验研究了其在初始预应力、满跨荷载和半跨荷载作用下的静力性能,获得了Levy型劲性支撑穹顶结构模型中各杆件内力和节点位移随外荷载增加变化规律。研究结果表明:在满跨荷载作用下,随着荷载的增大,环杆、撑杆和斜杆轴力都逐渐增大,脊索索力逐渐减小;在半跨荷载作用下,随着荷载的增大,结构内部杆件内力变化平稳,结构受荷一侧各杆件内力变化规律与全跨荷载作用下变化规律基本相同,但各杆件内力的变化值较全跨荷载作用大,结构对非对称荷载比较敏感,结构非受荷一侧内力变化比较复杂,脊索索力减小,撑杆和环索内力减小,内、中斜杆内力减小,外斜杆内力基本不变,半跨荷载引起的节点竖向位移比满跨荷载引起的竖向位移大,但整体结构位移均较小,竖向刚度较大,表明用劲性钢拉杆代替索穹顶下层拉索构件是可行的。研究结果验证了劲性支撑穹顶结构合理性与可行性,可为工程应用提供参考。

A 6 m span Levy rigid bracing dome(LRBD)model was tested for studying the static mechanical properties of the system.Three test cases were considered in this experiment,namely,only initial prestress,full-span load,and half-span load.With increasing load,the variation of internal force and nodal displacement of LRBD were obtained.The conclusions obtained are as follows:under full-span load,the internal force of the hook rod,bracing rod and slanting rod are increased,but the internal force of the ridge cable is decreases with increasing load;under half-span load,the internal force of the LRBD changes smoothly with increasing load,and the change of the internal force of the LRBD on the load side are similar to that of the LRBD under full-span load.However,the variation of the internal force of the LRBD under half-span load is larger than that under full-span load.It is shown that the LRBD under halfspan load are more sensitive to the load change.Under half-span load,the variation of the internal force of LRBD is complex.The internal force of the ridge cable decreases with load increasing.The internal forces of the bracing rod,hook cable,internal slanting rod and mid slanting rod decrease with increasing load,but the internal force of the outside slanting rod is basically unchanged.The vertical displacements of the nodes caused by half-span load are larger than those caused by full-span load.The displacement of the whole structure is smaller and the vertical rigidity of the LRBD is large.It is proved that it is feasible to replace the cables in the lower layer of cable dome with steel tie rods,which can provide some references for engineering application.