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对混凝土人字形密肋折板网壳与下部结构共同工作的动力特性,采用有限元方法计算24个算例,对比点支承网壳和屋盖与下部结构共同工作的自振频率与振型,有限元参数分析考虑屋盖矢跨比、肋刚度、脊线刚度和顶层抗侧刚度的影响。计算结果表明:屋盖点支承和与下部结构共同工作的自振频率分布均较为密集,点支承屋盖的振型主要为竖向振动,共同工作时,第1、2阶振型为平动振型,第3阶为扭动振型,高阶平动振型中伴随屋盖的竖向振动,屋盖不宜简化为理想点支承作抗震设计;屋盖矢跨比对整体结构前三阶频率的影响较小;提高顶层抗侧刚度有利于增大结构整体刚度;增大屋盖肋刚度时,结构整体刚度仍主要受下部结构刚度控制,屋盖肋截面在满足承载力需求前提下可按较小的高跨比确定;屋脊类似于屋盖拱向肋的系杆,不会影响结构整体刚度。
Twenty-four examples were calculated by finite element method, and the natural frequencies and mode shapes of the co-operating shell and roof with the substructure were contrasted. Finite element parametric analysis takes into account the effects of roof-span ratio, rib stiffness, ridgeline stiffness and topside stiffness. The calculation results show that the natural frequency distribution of roof point support and substructure work is more dense, and the vibration modes of point support roof are mainly vertical vibration. When working together, the first and second order vibration modes are translational Mode, the third order of torsional vibration mode, high-order translational vibration mode with the roof vertical vibration, the roof should not be simplified as the ideal point of support for seismic design; roof sag than the overall structure of the first three frequencies The stiffness of the top of the structure is still less affected by the stiffness of the lower structure. When the rib rigidity of the roof is increased, the overall stiffness of the structure is still mainly controlled by the stiffness of the substructure. Under the premise of meeting the requirements of bearing capacity, Of the high-span ratio to determine; Roof ridge similar to the roof rib tied, will not affect the overall structural stiffness.