大跨度单层空间网格结构连续性倒塌动力效应分析及简化模拟方法研究

为评估大跨度单层空间网格结构的连续性倒塌动力效应，并确定此类结构静力分析时所采用的荷载动力放大系数，构建了单层空间网格结构抗连续性倒塌的单自由度子结构模型，推导出考虑初始状态下子结构在线弹性、弹塑性阶段的动力放大原理，通过数值算例分析验证了其正确性。提出适用于单层空间网格结构的连续性倒塌动力效应简化模拟方法，通过算例验证后给出单层网壳结构荷载动力放大系数的建议取值范围。研究表明:不考虑初始状态时，弹性阶段下的位移动力放大系数、荷载动力放大系数趋势保持一致；弹塑性阶段下，随着塑性的发展，荷载动力放大系数逐渐减小，位移动力放大系数逐渐增大。考虑初始状态后，虽然两个动力放大系数的变化趋势未发生改变，但值均显著减小，与理论分析结论一致，因此必须考虑初始状态的影响。此外，对于单层网壳结构，当DCR<0.7时，建议荷载动力放大系数取1.7~1.9；当DCR>0.9时，建议取1.4~1.6。

DYNAMIC EFFECT ANALYSIS OF PROGRESSIVE COLLAPSE AND SIMPLIFIED SIMULATION METHOD OF LARGE-SPAN SINGLE-LAYER SPATIAL GRID STRUCTURES

To evaluate dynamic effects of progressive collapse and determine dynamic magnification factor for large-span single-layer spatial grid structures, a model of single degree of freedom was developed in this study. The principles of dynamic magnification considering initial conditions were derived when the sub-structures were elastic and elastic-plastic. The theories in this paper were validated through numerical examples. The simplified simulation method of dynamic effect, suitable for single-layer spatial grid structures, was put forward. On this basis, the value ranges of the dynamic magnification factor of single-layer latticed shells were given. The analytical results show that, neglecting initial conditions, the trend of the displacement and load dynamic magnification factor was consistent when the structures were elastic. With the development of the plastic area, the load dynamic magnification factor decreases and the displacement dynamic magnification factor increases respectively. It is obvious that initial conditions should be considered as the dynamic magnification factors considering initial conditions are smaller than those calculated when not considering the initial conditions. Furthermore, it is suggested that the load dynamic magnification factor should be 1.7~1.9 when the demand for the capacity ratio (DCR) is less than 0.7 and 1.4~1.6 when DCR is greater than 0.9 for single-layer latticed shells.