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文章以某大跨度钢屋盖-混凝土组合结构为研究对象,利用有限元分析软件MIDAS/Gen对下部支承结构的3种简化模型(铰接支座、弹性支座、考虑下部支承结构质量及刚度的支座)进行分析,得出桁架上、下弦杆的轴力及节点竖向位移随跨度的变化情况并与整体模型进行对比;对整体结构采用振型分解反应谱法研究不同阻尼比对整体结构抗震性能的影响。结果表明,下部支承结构的不同简化对桁架结构动力响应影响很大,不可简单地把下部支承简化为铰接支座与弹性支座,否则设计偏于不安全;结构材料阻尼不同,不能简单地取用某一种材料的阻尼比作为整体结构的阻尼比,确定合适的结构阻尼比,可以进一步提高整体分析的准确性。
Taking a long-span steel-roof-concrete composite structure as the research object, this paper uses the finite element analysis software MIDAS / Gen to analyze three simplified models of the lower support structure (hinged support, elastic support, considering the quality and stiffness of the lower support structure The results show that the axial forces of the upper and lower chords of truss and the vertical displacement of the joints vary with the span and are compared with the overall model. The vibration modes of the whole structure are used to study the effects of different damping ratios on the overall structure Seismic performance impact. The results show that the different simplifications of the lower support structure have a great influence on the dynamic response of the truss structure. The lower support can not be simply simplified as the hinge support and the elastic support, otherwise the design is unsafe. The damping of the structure material is different and can not be simply taken Using the damping ratio of a certain kind of material as the damping ratio of the whole structure and determining the appropriate structural damping ratio can further improve the accuracy of the overall analysis.