基于应变能密度的网壳结构抗震性能参数分析

Parametric analysis of seismic performance of single-layer reticulated shell structure based on strain energy density

基于结构应变能密度对单层网壳进行地震响应特性分析,提出了反映结构稳定工作状态特性的新型参数,即指数应变能密度和值参数。首先,绘制单层网壳在地震作用下的各种响应分布云图及响应曲线图,展示了既有的参数形式不能完全地表征结构的整体工作性能,特别是结构进入弹塑性工作阶段,这些参数难以体现结构与外荷载之间稳定和确切的工作特性。其次,尝试将所有单元的指数应变能密度相加,得到能够表征结构整体受力状态的指数应能密度和值参数。通过考察该参数在结构弹性和弹塑性工作阶段随地震动强度变化的规律,鉴证了指数应变能密度和值参数能够反映:结构工作状态的稳定性特征、结构从工作状态到失效状态的突变特征、以及失效状态的不稳定性特征。最后,根据观察所揭示的单层网壳工作特征,并结合最大节点位移参数,建议单层网壳动力破坏等级划分及分界指标,为深入进行单层网壳抗震分析和设计规范的改进提供参考。

A new parameter called exponential strain energy density sum parameter, which reflects the stability characteristic of structural working state, is proposed based on the strain energy density of structure for analyzing the seismic responses of single-layer reticulated shell structures. Firstly, contour graphs and curves for various responses of single-layer reticulated shell are plotted, exhibiting that the existing parameters are incapable of completely describing the entire working performance of structure, and particularly in the elastic-plastic working stage, the existing parameters cannot reflect the stable and exact working characteristics of structures due to external loads. Secondly, it is attempted to sum up the exponential strain energy density of all elements to obtain a new parameter. By investigating the changing feature of the new parameter with seismic intensity when the structure is working in elastic or elastic-plastic stage, it is found that the new parameter can reflect the stability characteristic of structural working state, the transition characteristic of structure from working state to failure state, and the instability characteristic of structure in failure state. Finally, according to the investigated working characteristics and the maximum nodal displacements of single-layer reticulated shell structures, the grading and division indices for seismic damage of the structures are proposed, which can be referred when conducting in-depth seismic analysis of shell structure and improving the corresponding design codes.